Advances in Operative Dentistry Roulet Vol 1 2001.pdf

Advances in Operative Dentistry

Advances inOperative Dentistry

Volume 1: Contemporary Clinical Practice

Edited by

Jean-Frangois Roulet, Prof Dr Med DentProfessor, Chairman

Department of Operative andPreventive Dentistry and Endodontics

Charite, School of Dental MedicineHumboldt University of Berlin

Berlin, Germany

Nairn H.F. Wilson, PhD, MSc, BDSProfessor, Chairman

Unit of Operative Dentistry and Endodontology

University Dental Hospital of ManchesterManchester, United Kingdom

Massimo Fuzzi, DMDPrivate Practice

Bologna, Italy

Quintessence Publishing Co, IncChicago, Berlin, London, Tokyo, Paris, Barcelona,

Sao Paulo, Moscow, Prague, Warsaw, and I stanbul

Library of Congress Cataloging-in-Publication Data

Advances i n operative dentistry : contemporary clinical practice /edited by Jean-Francois Roulet, Nairn H.F. Wilson, Massimo Fuzzi.

p. ; errIncludes bibliographical references and index.

ISBN 0-86715-402-0 (hardcover)1. Dentistry, Operative.[DNLM: l. Dentistry, Operative. WU 300 A2445 20011 1. Roulet,

Jean-Francois. 11. Wilson, Nairn H.F. 111. Fuzzi, Massimo.RK501 .A36 2001617.6'05--dc21

2001001460

© 2001 Quintessence Publishing Co, Inc

Quintessence Publishing Co, Inc551 Kimberly DriveCarol Stream, Illinois 60188www.quintpub.co m

All rights reserved. This book or any part thereof may not be reproduced, stored in a retrieval system,or transmitted in any form or by any means, electronic, mechanical, photocopying, or otherwise, withoutprior written permission of the publisher.

Lithography: S & T Scan, BerlinPrinting and Binding: DBC Druckhaus Berlin-Centrum

Printed in Germany

ISBN 0-86715-402-0

http://www.quintpub.com

http://www.quintpub.com

Contents

Contributors 7

Preface 11

Introduction 13E. Steven Duke

Chapter 1Protection of Dentin and Pulp 17Carlo Prati

Chapter 2Protection of the Pulp-Dentin Complex with Adhesive Resins 27Serge Bouillaguet and Bernard Ciucchi

Chapter 3Moisture Management with Rubber Dam in Operative Dentistry 35Karl-Heinz Kunzelmann

Chapter 4Tissue and Moisture Management in Operative Dentistry 49Stefano Patroni

Chapter 5Esthetic Anterior Restorations 57Jean-Francois Roulet and Roberto Spreafico

Chapter 6Direct Posterior Restorations-Techniques for Effective Placement 73Guido Goracci

Chapter 7The "Composite-up" Technique: A Simple Approach toDirect Posterior Restorations 87Gilles F. Koubi, Stefan Koubi, and Jean-Louis Brouillet

Chapter 8Materials and Luting Cements for Indirect Restorations 95Marco Ferrari, Alessandro Vichi, and Albert J. Feilzer

Contents

Chapter 9Indirect Restorations for Anterior TeethSpace-The Eternal ProblemRichard Ibbetson

Chapter 10The Control and Maintenance of Dentoperiodontal Relationshipsi n Indirect Anterior RestorationsSamuele Valerio

Chapter 11Advances in Bonded Ceramic Restorations for the Anterior DentitionPascal Magne

Chapter 12Computer Veneers with the Cerec 3Andreas Bindl, Wibke Apholt, and Werner H. Mormann

Chapter 13Esthetic Posterior Indirect RestorationsJean-Francois Roulet and Roberto Spreafico

Chapter 14Bonded Partial Restorations for Endodontically Treated TeethJean,Jacques Lasfargues, Frederic Bukiet, Gil Tirlet, and Frank Decup

Chapter 15The Oral and Dental Effects of AgingAngus W. G. Walls and Michael J. Noack

Chapter 16Operative Treatment for Elderly PeopleMichael J. Noack, Michael Wicht, and Angus W. G. Walls

Chapter 17Adhesive Techniques for the Management of Fractured andWorn Teeth in Elderly PatientsAngus W.G. Walls

Chapter 18Conservative Dentistry: Educational Patterns in EuropeAlphons J.M. Plasschaert and Sandro Rengo

I ndex

109

119

135

153

165

191

211

223

229

241

257

6

Contributors

7

Wibke Apholt, DDS Bernard Ciucchi, DMD, PhDSection for Tooth-colored and School Dental Clinics of Geneva

Computer Restorations Geneva, SwitzerlandClinic for Preventive Dentistry,

Periodontics and Cariology Frank Decup, DDSUniversity of Zurich Department of ConservativeZurich, Switzerland Dentistry and Endodontics

Faculty of Dental SurgeryAndreas Bindl, DDS University of Paris VSection for Tooth-colored and Montrouge, France

Computer RestorationsClinic for Preventive Dentistry, E. Steven Duke, MSD, DDS

Periodontics and Cariology Department of Restorative DentistryUniversity of Zurich School of DentistryZurich, Switzerland I ndiana University

I ndianapolis, Indiana, USASerge Bouillaguet, DMDSchool of Dental Medicine Albert J. Feilzer, DDS, PhDDepartment of Biomaterials Department of Dental Materials ScienceUniversity of Geneva ACTA's Institute of Dental CareGeneva, Switzerland Amsterdam, The Netherlands

Jean-Louis Brouillet, DCD, DSO Marco Ferrari, MD, DDS, PhDDepartment of Operative Dentistry Department of Dental MaterialsSchool of Dental Medicine School of Dental MedicineMarseilles, France University of Siena

Siena, ItalyFrederic Bukiet, DDSFaculty of Dental Surgery Guido Goracci, MD, DDSCharles Foix Hospital Department of Operative DentistryUniversity of Paris V School of Dental MedicineMontrouge, France University "La Sapienza" of Rome

Rome, Italy

Contributors

Richard Ibbetson, DDSPrimary Dental CarePostgraduate Dental InstituteUniversity of EdinburghEdinburgh, United Kingdom

Gilles F. Koubi, DDS, DSDDepartment of Operative DentistrySchool of DentistryMarseilles UniversityMarseilles, France

Stefan Koubi, DDS, PhDUniversity of Paris VParis, France

Karl-Heinz Kunzelmann, DDS, PhDDental SchoolUniversity of MunichMunich, Germany

Jean-Jacques Lasfargues, DDS,DSO, DEO

Department of Conservative Dentistryand Endodontics

Faculty of Dental SurgeryUniversity of Paris VMontrouge, France

Pascal Magne, DDSDepartment of Fixed ProsthodonticsSchool of DentistryUniversity of GenevaGeneva, Switzerland

Werner H. Mormann, DDS, PhDSection for Tooth-colored and

Computer RestorationsClinic for Preventive Dentistry,

Periodontics and CariologyUniversity of ZurichZurich, Switzerland

Michael J. Noack, DDS, PhDDepartment of Operative Dentistryand Periodontology

School of DentistryUniversity of CologneCologne, Germany

Stefano Patroni, LMD, MDPrivate PracticePiacenza, Italy

Alphons J.M. Plasschaert, DMD, PhDDepartment of Cariology

and EndodontologyCollege of Dental ScienceUniversity of NijmegenNijmegen, The Netherlands

Carlo Prati, DM, DMD, PhDDepartment of Dental ScienceSchool of DentistryUniversity of BolognaBologna, Italy

Sandro Rengo, MD, DDSDepartment of Conservative DentistrySchool of DentistryUniversity of NaplesNaples, Italy

Jean-Francois Roulet, DDS, PhDDepartment of Operative Dentistry,

Preventive Dentistry and EndodonticsHumboldt University (Charite)Berlin, Germany

Roberto Spreafico, MD, LMDPrivate PracticeBusto Arsizio, Milan, Italy

8

Contributors

Gil Tirlet, DCDLaboratory of BiomaterialsFaculty of Dental SurgeryUniversity of Paris VParis, France

Angus W.G. Walls, BIDS, PhDDepartment of Restorative DentistrySchool of DentistryUniversity of NewcastleNewcastle, United Kingdom

Samuele Valerio, MDPrivate PracticeBrescia, Italy

Alessandro Vichi, MD, DDS, PhDDepartment of Dental MaterialsSchool of Dental MedicineUniversity of SienaSiena, Italy

Michael Wicht, DDSDepartment of Operative Dentistry

and PeriodontologySchool of DentistryUniversity of CologneCologne, Germany

9

Preface

A career in dentistry is not an easy option;in fact, quite the contrary is true. Why?The answer, which also explains whatmakes dentistry such a great profession,says it all: Dentistry is ever-changing andrequires extreme versatility. A dentist musthave excellent manual skills; good three-dimensional perception; knowledge of allaspects of dental science, including den-tal technology and materials; and, at oneand the same time, be a good physicianwith the ability to successfully managepatients. Together with this special blendof attributes, dental practitioners in mostparts of the world where dentistry is al iberal profession must also be entrepre-neurial business managers.

At the inaugural ConsEuro meeting inBologna, Italy, May 2000, European inter-national experts reviewed the state of theart and science of operative dentistry.Sound knowledge and understanding iscrucial, but, in a practical discipline suchas dentistry, this foundation must bematched by high levels of technical skills.By way of an analogy: One can under-stand the principles of skiing and havedetailed knowledge of the musculoskele-tal structures and mechanisms necessaryto traverse a piste, but still be unable toski down a slope. Competence, which is amarriage of knowledge and skill, is the key.

Given that clinical competence is asimportant as scientific knowledge, manyof the ConsEuro keynote speakers pre-sented seminars on practical aspects ofcontemporary operative dentistry. Thisbook captures the essence of these semi-

nars, spanning all aspects of the practiceof state-of-the-art operative dentistry.Everyday procedures and the challengesthey pose are illustrated with a multitudeof figures, emphasizing the scientific basisof the restoration and esthetics of teeth.While the topics of the chapters rangefrom the preservation of tooth tissues andthe maintenance of tooth vitality to theplacement of direct and indirect restora-tions in anterior and posterior teeth, theyhave in common an underlying theme ofhigh-quality clinical outcome.

To complete the clinical elements ofthis book, there is consideration of opera-tive dentistry for the aging population.The rate of change in operative dentistryfor patients of all ages is increasing, andeducational systems must move with theti mes. It is therefore appropriate that thisbook concludes with an overview of exist-i ng and future educational programs inoperative dentistry.

Each and every practicing dentist,teacher of operative dentistry, and dentalstudent will discover much new informa-tion to mine from this ground-breakingbook.

Developing and editing this book onbehalf of ConsEuro has been a privilegeand an honor. It is our hope that all thosewho read and study this book will beencouraged to contribute to the furtheradvancement and excellence in the prac-tice of operative dentistry.

J.F. Roulet, N.H.F. Wilson, and M. FuzziBerlin, Manchester, and Bologna

11

I ntroduction

E. Steven Duke

Historically, textbooks on operative den-tistry have been directed toward dental stu-dents, who have a very limited knowledgeand scope of the discipline. Further, thedental student's experience with the prac-tice of operative dentistry is at an entry level,void of significant competence. As such,earlier texts have been very narrow in theirapproach to instruction and relied heavilyupon tradition and simplified techniquestaught almost in a "cookbook" fashion, withvery little critical thought expected from thestudents. Rather than a critical review bythe authors, approaches to operative den-tistry were presented as interpretations ofthe correct way of doing procedures. Thiswas usually followed by a list of suggestedreadings from various publications andother texts. However, it is important to notethat scientific peer reviews that provided thefoundation for the conclusions made inthese earlier texts were absent. Further,the texts addressed only the regions ofthe world where they were drafted, andmost recently many originated in NorthAmerica. 3,8

As an introduction to operative den-tistry, most textbooks would provide somebasic principles, procedures, or tech-niques, and were often said to addressthe "science" or "art" of operative den-tistry. While there was usually plenty ofart, the science was minimal in mosttextbooks. Often scientific referenceswere not provided; instead, only suggest-ed readings were presented for furtherpursuit of knowledge and validation.

Advances in Operative Dentistry differsgreatly along these lines. First, the text isnot an introduction to operative dentistry.The text is directed to the practicing clini-cian or advanced graduate student.Second, the chapters are a compilation ofscientific papers with numerous refer-ences cited to substantiate the materialpresented and set the stage for criticalthought. Third, a number of the chaptersdeal with technologies that are innovativeand peripheral to many established pro-cedures of operative dentistry presentedi n other texts. Yet, the reader may arguethat adequate evidence is or is not pre-sented. This is one unique feature of thistext-it provokes thought from the readerand may even spark further reading onthe part of readers who wish to more fullyunderstand a procedure or technique.This concept of an "interactive" text,which does not provide all the answersbut only opens the door for new knowl-edge, is a novel educational approachthat is being used more often in otherdisciplines.

Another unique feature of Advances inOperative Dentistry i s its acknowledge-ment of the constant presence of patientsi n dental practice. The chapters discussnumerous factors that influence treatmentoptions. For example, risk assessment isalways important when considering treat-ment options. Risk factors such as oralhygiene, demographics, socioeconomicstatus, and nutrition are all critical ele-ments when one considers an operative

1 3

I ntroduction

i ntervention. 1,2,4 Therefore,

an

operativei ntervention should include measures toreduce a patient's risk, such as a propernutritional profile, an alteration in systemicmedications, or an intervention that is fol-lowed and reassessed at a later date. Thisagain is in sharp contrast to the mind-setof most operative dentistry textbooks,which revolve around cutting tooth struc-

ture in a "proper" fashion. While properpreparation of a tooth is necessary, theremay be more appropriate alternatives toconsider. One would have to go to greatl engths to find this concept in traditionaloperative dentistry textbooks. For exam-ple, the possibility that a repaired restora-tion is just as definitive as a replacement

restoration should be considered. In fact,the repaired restoration may be the betterchoice when it conserves tooth structureand is based upon a philosophy of preser-vation of good oral health and tooth struc-tures for a lifetime. 5

I ssues that are seldom discussed inoperative dentistry textbooks relate topatient demographics and economics.Such parameters are just as important asthe most precise techniques that may bediscussed in the text. Regional issuesregarding the general oral health, educa-tional background on oral health issues,and economic conditions of a populationwill have a direct impact on the nature ofcare rendered. In most developed popula-tions of the world, edentulism is on thedecline. 6,10 I ncreasing is the number of par-tially or fully dentate patients. Parallel to thisis an aging population that is retaining teethwell into the later years of life. 9 I n manyi nstances populations are outliving theirnatural dentition, requiring extensiverestorative reconstructions. Such restorativeprocedures are costly and require greater

skill from the clinician. This will ultimatelyl ead to manpower issues, ie, there will notbe enough dentists to meet the oral healthdemands of most populations. Theexpanded use of dental auxiliaries and thepromotion of more effective preventivetherapies will be necessary measures tocounter the anticipated shortage.

The introduction of new technologies-such as CAD/CAM to enhance the costefficiency of dental care and air abrasionand the chemical removal of caries toencourage conservative cavity prepara-tion-and of new procedures, such asconservative preventive restorations, arediscussed. The acceptance of newlydeveloped technologies varies greatly indifferent regions of the world. However,knowledge about innovation carries littlecost and should be shared by all scien-tists and educators. The final integrationi nto a regional practice will result after acomprehensive review and assessmentby individual regions and professionals.Presumptions about what is an appropri-ate global view of operative dentistry arewithout logic or scientific foundation.

I n summary, Advances in OperativeDentistry is a comprehensive presentationof the multifactorial relationships that influ-ence and govern the nature of operativedentistry. Numerous questions remain, asthey should, because of the scientific foun-dation of the manuscripts compiled. As ourpopulations evolve, so should the guide-lines of practicing operative dentistry. Asnew knowledge is gained, it should bei ncorporated into practice as soon as pos-sible to best suit the challenges facingclinicians around the world. Science hasno geographic boundaries, and the worldcollectively can contribute much to advanc-i ng the practice of operative dentistry.

1 4

References

References

1. Anusavice KJ. Decision analysis in res-torative dentistry. J Dent Educ 1992;56:812-822.

2. Bader JD, Shugars DA. Variation in den-tists' clinical decisions. J Publ Health Dent1995;55:181-188.

3. Black GV. A Work on Operative Dentistry.Vol 1: The Pathology of the Hard Tissuesof the Teeth. Chicago: Medico-Dental, 1908.

4. Johnson N (ed). Risk Markers for OralDiseases. Vol 1: Dental caries: Markers ofhigh and low risk groups and individuals.Cambridge, UK: Cambridge Univ Press,1991.

5. Mjor IA. Repair versus replacement offailed restorations. Int Dent J 1993;43:466-472.

6. Murray JJ. Oral health for the 21 st century.I n: Murray JJ (ed). Prevention of OralDisease. Oxford: Oxford Univ Press, 1996;275-276.

7. Reinhardt JW, Douglass CW. The need foroperative dentistry services: Projecting theeffects of changing disease patterns. OperDent 1989;14:114-120.

8. Sturdevant CM, Roberson TM, HeymannHO, Sturdevant JR (eds). The Art andScience of Operative Dentistry. St. Louis:Mosby, 1995.

9. Truono EJ. The aging population and itsi mpact on the future of dentistry-A sym-posium. J Am Coll Dent 1991;58:14-16.

10. World Health Organization. Recent Ad-vances in Oral Health. Report of a WHOExpert Committee [Technical ReportSeries 826]. Geneva: World HealthOrganization, 1992.

1 5

Chapter 1

Protection of Dentin and Pulp

Carlo Prati

I ntroduction

The use of adhesive techniques in recentyears has expanded to the extent that it isquestionable, if not anachronistic, to dealwith the problems of dentinal and pulpalprotection under conventional amalgamrestorations. Hence, only the problems ofpulpal-dentinal protection in modern ad-hesive dentistry are examined.

Dentin is a permeable substrate thatcovers but does not fully protect pulpal tis-sue. However, because enamel coversdentin, whenever enamel is altered or re-moved (as in caries, fractures, etc) bothdentinal and pulpal tissues are in danger.For these reasons, it is difficult to limit pre-sent considerations to dentinal and pulpalprotection. The preservation of soundenamel is probably the best solution forcomplete protection of dentin and pulp.Despite such apparently simple consider-ations, we must answerthe following ques-tions:

1. What causes of dentinal and pulpal da-mage are involved in failures in modernadhesive dentistry?

2. How can one protect dentin and pulpaltissues during the life of a restoration? Isthe protection of dentin and pulp reallynecessary with modern materials?

3. Does the protection of restoration mar-gins also protect the pulp-dentin com-plex?

The aims of this chapter are to examinecritical aspects of restorative techniquesand restoration performance that requirethe protection of dentin and enamel.

Causes of Dentinal Damage

The causes of dentinal damage are relat-ed to the penetration and growth of bacte-ria inside dentinal tubules and in the denti-nal smear layer. During the preparation ofa cavity, a large number of bacteria may bei ntroduced into the cavity and contaminatethe smear layer. For these reasons, a rangeof disinfectant solutions were previouslyproposed 2 to reduce the number of bac-teria in the surface of prepared dentin. 3The materials proposed to disinfect dentinand enamel after cavity preparation are setout in Table 1-1. Today, with the use of etch-ing solutions and self-etching primers, it isunlikelythatthedentinalsurface will remaincontaminated prior to the application ofcomposite materials. In fact, acid solutions( pH 0.8-2.0) probably remove all bacteriapresent on the floor and walls of a cavity.

17


Table 1-1 Materials used to reduce damage to tooth tissues

While it is possible to reduce the num-ber of bacteria immediately priorto restora-tion placement, it remains a great problemto reduce bacterial growth in gaps be-tween restoration and dentin (and restora-tion and enamel) during the life of therestoration. The biofilms and associatedbacteria that completely cover restorationsurfaces and infiltrate marginal gaps arethe most important etiologic factors in sec-ondary caries, associated enamel disinte-gration, pulpal damage, and pulpitis. Inother words, bacteria and their toxic prod-ucts are the major source of pathologicdamage to dentin and pulp subsequent tobacterial infection. For these reasons, theprotection of the pulp-dentin complexrequires the protection of restoration mar-gins. Unfortunately, bacteria and their fer-mentation products may alter enamel anddentin along the margins of a restoration,especially if the margin of the restorationhas a porous, demineralized, andpermeable structure. 1,5,11 The greater thepermeability of affected dentin, the morepostoperative pain and sensitivity can beexpected. 12 I t is well-known that pain is re-lated to the rate of permeability. If dentin iswell sealed, there is no fluid flow outwardfrom the pulp and dentin permeability is

1 8

very low or absent. For these reasons, post-operative sensitivity might represent an in-dex of the sealing capacity of restorationmargins.

Mechanisms of DentinalDamage

When a gap is present along the marginof the restoration, there is a wide open"window" for bacteria to gain access to thepulp. The more the window is open, thegreater the bacterial penetration of thedentinal tubules will be. Greater dentinalpermeability means higher risk of dentinaland pulpal damage. Complete absence ofpermeability means good protection andperfect prevention. Probably all restora-tions have at some time one or more openwindows destined to open ever wider; fail-ure is therefore only a question of time!

Bacterial progression toward pulp doesnot, however, mean early pulpal damage(and pain). If the gap is limited, the outwardfluid flow can wash away many bacteriaand may limit pathologic alterations.However, reduced pulpal vitality with areduced pulpal gradient and pressure isunlikely to produce a flow rate sufficient to

Table 1-2 Materials used to achieve external protection of restoration margins

oppose bacterial progression. 12 I t is alsoimportant to remember that outward fluidflow around a filling does not prevent achemical gradient directed pulpally. 2 Thefluid flow rate around new restorationsplaced in mesio-occlusodistal Class 11 cav-i ties using a total-etch/bonding system, aconventional bonding agent, or a glass-ionomer cement base has been investi-gated. 18 The outward fluid flow may be de-tected immediately following the applica-tion of the restorative materials and onlypartially correlates with the findings of mi-croleakage tests. 18 This work demonstrat-ed that fluid flow persists for a relativelylong time (about 3 months) and may influ-ence the adhesion of bonding agents andmarginal integrity. 14,16,17 1 n another prelimi-nary clinical study, the postoperative painand sensitivity level following the provisionof ceramic crowns to restore molars andpremolars was monitored. Different typesof adhesive systems were compared. Thecomplete hybridization of the dentinal sur-face eliminated pain and sensitivity during

Concept of "Internal" and "External" Protection of Restorations

impression procedures and prevented anysignificant sensitivity during the first year ofevaluation. Other clinical studies have con-firmed the excellent biocompatibility ofmodern dentin-enamel bonding systems. 7

Concept of "Internal"and "External" Protection ofRestorations

It is clear that it is extremely important tominimize the marginal gap around arestoration (the open window) and to rein-force all the mechanisms that can keepthis "window" closed. Methods for the so-called "external protection" of restorationsare listed in Table 1-2. External protectionincludes all the systems able to preventmarginal alterations and degradation, re-duce secondary caries, and mantain theinterface between restoration and remain-i ng tooth tissues.

Methods for the "internal protection"restorations are listed in Table 1-3. These

19


Table 1-3 Materials used to achieve internal protection of restoration margins

Table 1-4 Dentinal marginal microleakage observed in three groups of materials after immersion in eithersaline or a cariogenic solution for 1 week"

`Storage in the acidic enviroment caused demineralization in the region of margins with an increase in microleakage.( Groups with the same superscripted letter are statistically equal.)

methods play an important role only whenexternal protection has failed. Internal pro-tection of dentin means control of perme-ability and better control of fluid flowrate. 12-14,16-18

Of course, an outstanding question iswhy windows open, or rather, why may themargins of a restoration develop manychannels, gaps, and fractures, creating ac-cess for bacteria? The causes of marginalalterations in new restorations (compositeshrinkage, lack of adhesion, etc) are well-known and better described elsewhere inthis book. The causes of acquired margin-al alterations include: occlusal loading,cuspal flexure, chemical degradation, andmost importantly incomplete hybrid layer

formation and alterated hybrid layer mor-phology. 6,7.19-21

Chemical degradation of the marginali ntegrity of restorations (enamel anddentin) is probably the most importantcause of microleakage and bacterial inva-sion. 19 I n a laboratory study, it has beendemonstrated that microleakage may beminimized by using appropriate dentinaland enamel bonding systems. Alterationsof tooth tissues (demineralization and sec-ondary caries) around the margins (orthe marginal hybrid layer) of restorationsdramatically increase microleakage, asshown in Table 1-4. Tissues around therestoration provide the foundation formarginal integrity throughout the life of

20

Methods to Prevent Marginal Alteration

the restoration. Scanning electron micro-graphs illustrate the typical alterations inenamel and dentin around different typesof restorations after storage in an artificialcariogenic solution. Alterations to the mar-ginal tissues create many porosities andvoids, allowing large numbers of bacteriato "run" into deeper parts of the dentin andpossibly the pulp. Porosity of enamel and,i n particular, dentin is an important causeof pulpal-dentinal alterations. In otherwords, secondary caries increase, porosi-ties, and the resulting channels betweenthe oral environment and the pulp-dentincomplex invite pulp disease. The area im-mediately adjacent to the margin of therestoration must be kept intact (ie, free ofcaries) to prevent any type of subjacentdamage.

Methods to Prevent MarginalAlteration

The mechanisms to prevent early margin-al alterations, such as the control of com-posite shrinkage and the limitation of initialocclusal loading are discussed elsewhere.The issue in the present review is how toprevent marginal alterations during the lifeof the restoration and maintain the healthof the pulp.

Several years ago glass-ionomer ce-ments were promoted as fluoride-releas-i ng materials. All the fluoride-releasingmaterials now present on the market(resin-reinforced glass-ionomer cements,compomers, ionomers, etc) may protectenamel margins. Several laboratory inves-tigations have demonstrated such aneffect . 5,10,21 Recent scanning electron mi-croscopic (SEM) analyses failed to demon-strate any important effects of fluoride-re-

l easing materials in preventing enamelmarginal alterations after storage in cario-genic solutions (lactic acid, pH 4.6) for 1week and 1 month (Figs 1-1 to 1-6). The au-thor's initial enthusiam for fluoride-releas-ing materials has been partially eroded bythe lack of robust clinical evidence.However, further studies are required be-fore discontinuing investigations of thesematerials in the author's laboratories.Several new formulations may be found toprotect the enamel prisms close to thetooth-restoration interface. Others may befound to reduce the amount of bacteria inplaque and oral biofilms and thereby con-tribute to a reduction in secondary caries.

It is acknowledged, however, that manystudies have demonstrated significantlyhigher levels of remineralization in toothtissues adjacent to glass-ionomer-filledcavities compared with amalgam-filledcavities. 5 I n another recent study, Hsu etalb demonstrated that fluoride-containingamalgam and glass-ionomer cements canelicit a significant preventive effect on sec-ondary root caries in an in vitro bacterialmodel system. In an interesting laboratorystudy, Dijkman and Arends 6 i nvestigatedthe effect of a fluoride-releasing compositeon enamel demineralization along the in-terface gap found around restorations.Their results indicate that fluoride-releas-ing composites may play a role in the fu-ture prevention of secondary caries be-cause they can prevent the "intragap"demineralization of enamel . 6 This findingsuggests that enamel in a gap may be pro-tected by acid demineralization and there-by help preserve-albeit partially-therestoration. Future studies must producemore information on the role of fluoride inpreventing secondary caries and marginaldemineralization.

21


Fig 1-1 Marginal hybrid layerwithgaps, fractures, and voids. Thesefractures represent the "window"for bacterial penetration towardthe pulp.

Fig 1-2 Perfect marginal adapta-tion. The characteristic morpholo-gy of composite resin is apparent.The thickness of the bondingagent are approximately 10 um.This is the typical morphology ofthe marginal hybrid layer.

Fig 1-3 Marginal hybrid layer of arestoration stored in saline solu-tion. Compomer (left) and theenamel margin are clearly visible.Porosity of the enamel around themargin of the restoration is evi-dent.

22

Fig 1-4 Marginal hybrid layer.The erosion and demineralizationof dentin are clearly visible alongthe margin. This alteration maycontribute to an increase inthe marginal gap and to the for-mation of microchannels withinthe dentin-hybrid layer interface.Permeability of dentin is extreme-ly high close to the margin of arestoration.

Fig 1-5 Marginal hybrid layerwith gaps and voids. The thick-ness of the hybrid layer is approx-i mately 3 um. Dentinal tubuleshave been opened during immer-

sion in a demineralizing solution.The removal of collagen has ex-posed many dentinal tubules andchannels.

Fig 1-6 Typical enamel lesion( enamel demineralization) ob-served along the margin of arestoration. The integrity of theenamel surface was lost duringi mmersion in cariogenic solutionfor 1 week to simulate in vivo al-terations. The use of compomersdid not significantly improve theprotection of enamel.

Methods to Prevent Marginal Alteration

23


Fig 1-7 Maxillary molar with secondary caries in a21-year-old patient with no pulpal symptoms, no-tably pain and thermal sensitivity.

Fig 1-8 Appearance of the maxillary molar follow-i ng removal of the old restoration. The pulp is ex-posed, as confirmed by the presence of blood.

Fig 1-9 The application of a glass-ionomer cementmay reduce the risk of further pulpal problems.

Methods of Preventing Pulpal-Dentinal Alterations

The available literature, which is relativelyl imited, confirmsthatthe use of modern to-tal-etching and self-etching systems doesnot increase the incidence of pulpalpathology. 4 This means that current clini-cal procedures and materials are safe anddo not cause serious pulpal damage. Inthe author's clinical studies, no attempthas been made to investigate problems re-lated to the use of bonding systems. The

author used a bonding system for directpulpal capping without any serious diffi-culties (Figs 1-7 to 1-9). It therefore may besuggested that in most cavities pulpaldamage (with pain and sensitivity reportedby patients) is unlikely. Other informationcontinues to be published pertaining to di-rect pulpal capping with bonding agentsand composite resins. 9

The use of calcium-hydroxide cementsmay have a rationale; however, there are norobust studies able to demonstrate thesafety and hazards, if any, of such materi-als. Resin-reinforced glass-ionomers have

24

Conclusions

a well-documented antibacterial activity 15and good adhesion to dentin, and maythus bean alternative to calcium-hydroxidecements in very deep cavities.

Several studies have recently demon-strated that the use of dentin-enamelbonding systems is both safe and free ofadverse pulpal effects. The formation of athin but impermeable hybrid layer best pre-vents any pulpal damage by sealing dentinthrough the closure of dentinal tubules. Inother words, a hybrid layer protects dentinand pulp. All methods able to produce acomplete hybrid layer may be included inthe methods used to prevent pulpitis andsecondary caries.

Conclusions

Pulpitis, pulpal damage, dentinal alter-ations, and caries are caused by bacteriaand their products moving inward towardthe pulp. Using the materials able to sealthe external margins and the inner aspects

of cavity walls is the correct method to pro-tect pulp and dentin. The reduction ofdentinal permeability is a goal in preventivedentistry.

Demineralization of dentin aroundrestoration margins opens a fine networkof dentinal channels and lateral anasto-moses, which are the site of the mi-croleakage that occurs around margins.SEM evaluations have confirmed the pres-ence of gaps and debris around the mar-gins of restorations. Many porosities havebeen observed 50 to 100 um from thedentinal surface. In several samples, frac-tures and chips along the margins of com-pomers were observed. These observa-tions suggest that such materials are notable to resist acid attack and may bedemineralized by acid biofilms.

The prevention of marginal alterations(external protection) and the hybridizationof dentin (internal protection) are the mostmodern and effective methods to preventdentinal and pulpal damage.

25


References

1. Arends J, Ruben J, Jongebload WL. Dentincaries in vivo. Caries Res 1989;23:36-41.

2. Brannstrom M. Communication between theoral cavity and the dental pulp associated withrestorative treatment. Oper Dent 1984;9:57-68.

3. Brannstrom M, Nyborg H. Cavity treatment witha microbicidal fluoride solution: Growth of bac-teria and effect on the pulp. J Prosthet Dent1973; 30:303-310.

4. Cox CF, Keall CL, Keall HJ, Ostro E, BergenholtzG. Biocompatibility of surface-sealed dental ma-terials against exposed pulps. J Prosthet Dent1987;57:1-8.

5. Creanor SL, Awawdeh LA, Saunders WP, FoyeRH, Glimour WH. The effect of a resin-modifiedglass-ionomer restorative material on artificiallydemineralized dentine caries in vitro. J Dent1998;26:527-531.

6. Dijkman GEHM, Arends J. Secondary caries insitu around fluoride-releasing light-curing com-posites: A quantitative model investigation onfour materials with a fluoride content between 0and 26 vol%. Caries Res 1992;26:351-357.

7. Goracci G, Mori G, Bazzucchi M. Marginal sealand biocompatibility of a fourth-generationbonding agent. Dent Mater 1995;11:343-347.

8. Hsu CYS, Donly KJ, Drake DR, Wefel JS. Effectsof aged fluoride-containing restorative materialson recurrent root caries. J Dent Res 1998;77:418-425.

9. Kitasako Y, Arakawa M, Sonoda H, Tagami J.Light and scanning electron microscopy of thei nner surfaces of resins used in direct pulp cap-ping. Am J Dent 1999;12:217-221.

1 0. Kreulen CM, de Soot JJ, Weerheijm KL, vanAmerongen WE. In vivo cariostatic effect of resinmodified glass ionomer cement and amalgamon dentine. Caries Res 1997;31:384-389.

1 2. Pashley DH, Carvalho RM. Dentine permeabili-ty and dentine adhesion. J Dent 1997;25:355-372.

13. Pereira PNR, Inokoshi S, Yamada T, Tagami J.Microhardness of in vitro caries inhibition zoneadjacent to conventional and resin-modifiedglass ionomer cements. Dent Mater 1998;14:179-185.

1 4. Prati C, Chersoni S, Mongiorgi R, Pashley DH.Resin-infiltrated dentin layer formation of newbonding systems. Oper Dent 1998;23:185-194.

15. Prati C, Fava F, Di Gioia D, Selighini M,Pashley DH. Antibacterial effectiveness ofdentin bonding systems. Dent Mater 1993;9:338-343.

16. Prati C, Ferrieri P, Galloni C, Mongiorgi R,Davidson CL. Dentine permeability and bondquality as affected by new bonding systems. JDent 1995;23:217-226.

1 7. Prati C, Pashley DH. Dentin wetness, perme-ability and thickness and bond strength of ad-hesive systems. Am J Dent 1992;5:33-38.

1 8. Prati C, Tao L, Simpson M, Pashley DH. Per-meability and microleakage of Class II compos-ite resin restorations. J Dent 1994;22:49-56.

19. Tay FR, Gwinnett JA, Pang KM, Wei SHY.

Structural evidence of a sealed tissue interfacewith a total-etch wet-bonding technique in vivo.J Dent Res 1994;73:629-636.

20. Tay FR, Gwinnett JA, Wei SHY. Micromor-phological spectrum from overdrying to over-wetting acid-conditioned dentin in water-freeacetone-based, single-bottle primer/adhesives.Dent Mater 1996;12:236-244.

21. Tay FR, Gwinnett JA, Wei SHY. Relation be-tween water content in acetone/alcohol-basedprimer and interfacial ultrastructure. J Dent1998; 26:147-156.

11. Lagerweij MD, Damen JJM, ten Cate JM.Demineralization of dentine grooves in vitro.Caries Res 1996;30:231-236.

2 6

Chapter 2

Protection of the Pulp-Dentin Complexwith Adhesive Resins

Serge Bouillaguet and Bernard Ciucchi

I ntroduction li mit the incidence of adverse pulpal reac-tions.

The demand for esthetic restorations andworries about the toxicity of mercury havedriven the replacement of dental amalgamby adhesive resins. While efficient bondingto dental tissues appears to be guaranteedunder laboratory conditions, such reliabili-ty is not always encountered in clinical use.This observation is to an extent supportedby the low but constant incidence of pul-pal sensitivity problems reported followingthe placement of adhesive restorations.Fortunately, most of these reactions are mi-nor and reversible; some, however, aremore pronounced. The intensity of the pul-pal response to bonding and restorativeprocedures is modulated by different fac-tors. The first of these is undoubtedly re-lated to the protective effect afforded bydentin and the pulp. The ability of resins towet dentin surfaces, resist polymerizationstresses, and seal the restoration are all fur-ther factors that affect the pu I pal response.This chapter briefly reviews the function ofthe pulp-dentin complex and attempts todefine the risks of adverse pulpal reactionsduring restorative procedures. Clinical rec-ommendations are discussed in an at-tempt to optimize bonding to dentin and to

Anatomy of the Dentin andPulp

Pulp and dentin form a common organ.The pulp's primary function is the produc-tion of mineralized tissues, and the miner-alized dentin plays a protective role forthe pulpal tissues. When exposed topathologic processes (caries, attrition, andabrasion) or to restorative procedures (cav-ity preparation), various interactions be-tween dentin and pulp may be found to oc-cur. However, the respective contributionsof these reactions to the control and regu-lation of noxious stimuli are somewhat dif-ferent. In dentin, the presence of dentinaltubules makes the dentin permeable, andit is apparent that noxious substances canreadily move across it by diffusion.Fortunately, there is also evidence of an in-teraction between dentin and certain mol-ecules that can be trapped or bound in-side the dentinal tubules.14 As a result, theconcentrations of noxious substances atthe pulpal openings of the dentinal tubulesare reduced. However, this permeability is

2 7

Protection of the Pulp-Dentin Complex with Adhesive Resins

not uniform throughout the crown of thetooth. 17 Close to the pulp, the permeabilityi s ten times that measured at the periphery,with dentinal permeability varying fromone region of the crown to another.Differences in dentinal permeability havebeen observed between young and ageddentin and may be attributed to variousamounts of materials deposited within thetubules (sclerosis). 17 It is generally accept-ed that deep dentin is a poor barrierto bac-terial, chemical, and physical stimuli. Suchstimuli are usually accompanied by painand related pulpal reactions.

The dental pulp has a complex vascularand nervous supply that permits, amongstother functions, inflammatory reactions,the control of the steric balance of intersti-tial fluids, and maintenance of a constanttissue pressure. 18 As soon as dentinaltubules are opened, the positive pulpal tis-sue pressure tends to flush dentinal fluidthrough the dentin. 7 This outward convec-tive fluid movement reduces the concen-tration of noxious substances in thediffusates. Also, pulpal blood flow con-tributes to the removal of toxic dentin-dif-fused materials from the pulp. 19

Sensory nerve fibers respond to cavitypreparation by releasing neuropeptides re-sponsible for neurogenic inflammation. 6These mediators activate the release fromblood vessels of plasma proteins that mi-grate into dentinal tubules and cause a de-crease in dentinal permeability. Whendeep cavities are prepared, there is a se-vere pulpal reaction, given disruption tothe odontoblast cell layer. Cell damage willtrigger increased inflammatory reactions,mostly oriented toward the production ofreparative dentin at the site of injury.

These observations support the con-cept that deep dentin is more vulnerable

than superficial dentin to cavity prepara-tion. Anything that can diminish convectivepulpal fluid movements and diffusiontransport processes across dentin shouldreduce the incidence of adverse pulpalreactions.

Protection of the Pulp-DentinComplex

Theoretically, dentin hybridization shouldprovide strong and durable micromechan-ical retention of resins and complete seal-i ng of the restoration without the risk of pul-pal toxicity. 16 When such conditions areobtained clinically, the risk of pulpal irrita-tion by adhesive restorations is prevented.However, recent reports have identifiedfactors that may affect the quality of bond-i ng, especially to dentin. As reported byErickson, dentin is a heterogeneous sub-strate that significantly influences thebonding properties of current adhesivesystems.10 The type of dentin (young orsclerotic), its variations in composition(high water content versus high mineralcontent) and permeability (high versus lowpermeability), and the ability of a resin towet such surfaces are all factors that will af-fect adhesion. The handling of adhesivesystems also may have profound reper-cussions on the quality of bonding. With to-tal-etch/wet-bonding systems, excessiveetching of the dentin can produce poorbonding when collagen fibers at the baseof the demineralized dentin are not com-pletely impregnated with resin (Figs 2-1 a to2-1 d). 1 9 Furthermore, there is a risk of col-lagen collapse after etching. Moisture con-trol has been shown to be critical undersuch clinical conditions. 22 Other studieshave reported that combining primer and

28

adhesive resins to allow a single applica-tion step may reduce the effectiveness ofhybridization. 23 One approach to preventthe risk of defective dentin hybridization isthe use of self-etching adhesive systems(Figs 2-2a to 2-2c). With these systems,etching and priming of the dentin can oc-cur simultaneously by infiltration of thesmear-covered dentin with acidic resins( Figs 2-2a to 2-2c). Therefore, critical pro-cedures such as rinsing after etching andthen drying of the dentin are eliminated.Furthermore, the risk of incomplete im-pregnation of the demineralized dentin bythe resin is avoided. Recently, it has beendemonstrated that self-etching adhesivescan exhibit bonding characteristics equiv-alent to those of most current adhesivesystems. 3

Another factor that may influence thequality of bonding is the configuration ofthe cavity.11 This has been confirmed in arecent study that showed that the adhesivecharacteristics of a bonding agent to thewalls of a Class 11 cavity were significantlyreduced compared to those obtained onflat dentinal surfaces. 8 I t is speculated,however, that the placement of thick ad-hesive layers can counteract the stressesgenerated during the polymerization of therestorative material. 9

Despite the mechanical resistance ofthe adhesive interface, it is essential tocounter polymerization stresses, especial-ly given the increasing evidence that per-fect sealing of the restoration is required toprevent bacterial leakage.' It is interestingto note that even in the presence of strongadhesion, incompletely infiltrated hybridl ayers can still permit leakage through sub-microscopic porosities within the hybridzone. 21 Surprisingly, most adhesive sys-tems cannot eliminate the passage of fluid

Protection of the Pulp-Dentin Complex

across bonded interfaces because of de-fective hybridization. Notwithstanding a90% reduction in dentin permeability afterbonding, persistent permeation of fluid af-ter bonding may be observed with somematerials. 2 This result has been attributedto the incomplete evaporation of the sol-vent in the primer system (overwet phe-nomenon) or to the incomplete polymer-ization of the resin (excessive thinning ofthe adhesive layer). It is generally acceptedthat persistent permeation of fluids will in-crease the risk of postoperative sensitivityand can accelerate the degradation of theadhesive resin in clinical service.

The final point to be considered whenevaluating the quality of bonding is the ab-sence of pulpal toxicity. Despite biocom-patibility studies that report that bacteriall eakage is more likely to cause adverse ef-fects to the dental pulp than componentsfrom restorative materials, other reportshave indicated that resin molecules aretoxic at micromolar concentrations. 1,13,20

The risk of toxic effects is further increasedby the potential for adhesive materials toleach intothe pulpaltissues given thetubu-lar structure of the dentin. During bondingprocedures, the risk of chemical irritationi s present. Such irritation could un-doubtably trigger an immediate pulpal re-sponse. Fortunately, the concentrations ofleached components from resin compos-ites do not appear to cause acute toxicityto odontoblasts and therefore most reac-tions observed are minor and reversible. 4.12

More interesting are the long-term subtox-ic effects on pulpal cells resulting from theprogressive degradation of poorly poly-merized adhesive resins diffusing down tothe pulp. Recent studies indicate that verylow concentrations of resin monomers,which are known to pass through dentin

29


Figs 2-1a to 2-1d Bonding to dentin with conventional (three-step) adhesive systems.

Fig 2-1a Dentinal substrate after acid etching. Thesmear layer has been removed and both the per-itubular and intertubular dentin are demineralized.The collagen fibers are exposed and bathed in wa-ter. This substrate is highly hydrophilic and particu-l arly sensitive to dehydration. The blue colorationrepresents the water content of the structures illus-trated.

30

Fig 2-1b Dentinal substrate after priming. The wa-ter has been replaced by hydrophilic resins( primers) that have impregnated the collagen fibers.The solvent of the primer can be organic (alcohol oracetone) or inorganic (water). Priming with water-based primers is a relatively slow process, while or-ganic solvents will displace water more rapidly (con-vective movement). Evaporation of the solvent willl eave the collagen fibers coated and stiffened by theresins. The substrate has changed from hydrophilicto hydrophobic. The red coloration represents theextent of primed dentin.

Protection of the Pulp-Dentin Complex

Fig 2-11c Dentinal substrate after adhesive resin ap-plication. The hydrophobic resin diffuses slowly intothe dentinal tubules and impregnates the intertubu-l ar dentin. If resin penetration is not complete, it willl eave noninfiltrated areas of demineralized dentinand nonadherent resin plugs. These defects are re-sponsible for poor sealing of the dentin and rapiddegradation of the adhesive interface.

Fig 2-1d Dentinal substrate after polymerization ofthe adhesive resin. The polymerized resin has com-pletely infiltrated the demineralized dentin and of-fers effective protection to the pulp-dentin complex.

31


Figs 2-2a to 2-2c Bonding todentin with a self-etching adhe-sive system.

Fig 2-2a Dentinal substrate afterpreparation. Smear layer is cov-ering the dentin and smearplugs are occluding the dentinaltubules. These structures con-tribute greatly to a reduction indentinal permeability.

Fig 2-2b Dentinal substrate afterapplication of acidic resins. Theresins have dissolved and im-pregnated the smear layer as wellas some intertubular dentin. Theresins have also penetrated thedentinal tubules.

Fig 2-2c Dentinal substrate afterapplication of the adhesive resin.The resin has simply coated theprimed surfaces without any riskof incomplete penetration. Thisbonding procedure is very effec-tive in deep dentin.

32

Conclusions

by diffusion, can have significant effects onthe proliferation and activity of humanmonocyte-macrophages. 5,15 Consequent-ly, the potential for bacterial injury to thedental pulp may be enhanced since its re-sistance to infectious agents is decreased.This problem is likely to become moreacute when bacterial leakage occurs withthe progressive biodegradation of the ad-hesive resins in long-term clinical service.

Clinical Recommendations

To optimize bonding, one should evaluatethe potential of each adhesive system un-der specific clinical conditions. Shallowcavities located in superficial or scleroticdentin can be treated using a low-viscosi-ty self-priming adhesive system (one-bottleadhesives) that will simultaneously bond toenamel and dentin. Successive incre-ments of filling material should be appliedand properly photo polymerized. Whendeeper cavities are prepared, one shouldconsider using a conventional (three-step)adhesive system, given that such systemsfacilitate control of the thickness of the ad-hesive layer. Athick adhesive layerwill givesome elasticity to an adhesive interface tocompensate for the volumetric shrinkageof the composite material. Thicker adhe-sive layers also may be obtained with filledadhesive resins or by using low-viscosity

composite liners after bonding. Deep cav-i ties in young patients require a differentapproach to avoid adverse reactions tobonding. In such situations, the dentin ishighly permeable and the volume of com-posite material is particularly important.The use of a self-etching adhesive systemprovides a uniform hybridization of thedentin without the risk of imperfect im-pregnation of the dentinal surface that isencountered with total-etch systems. Withthese systems, bonding to enamel mar-gins can be optimized using a separate37% phosphoric acid etchant to providemaximum sealing at the periphery of therestoration. Thus, optimum sealing of bothdentin and enamel margins can be real-i zed.

Conclusions

There is increasing evidence that thepulp-dentin complex can react positivelyto adhesive restorations, given the useof appropriate operative techniques.Adhesive systems have the potential toseal restorations and, as a consequence,to offer effective protection of the pulp-dentin complex. This potential is, however,challenged by the complexity of bondingprocedures and the limitations of bondingsystems relative to the microdiversity of thedentinal substrate.

33


References

1. Bergenholtz G, Cox CF, Loesche WJ, Syed SA.Bacterial leakage around dental restorations: Itseffect on the dental pulp. J Oral Pathol 1982;11:439-450.

2. Bouillaguet S, Duroux B, Ciucchi B, Sano H.Ability of adhesive systems to seal dentin sur-faces: An in vitro study. J Adhesive Dent2000;2:201-208.

3. Bouillaguet S, Gysi P, Ciucchi B, Cattani M,Godin Ch, Meyer JM. Bond strength of com-posite to dentin using conventional, one-step,and self-etching adhesive systems. J Dent2001;29:55-61.

4. Bouillaguet S, Wataha JC, Hanks CT, Ciucchi B,Holz J. In vitro cytotoxicity and dentin perme-ability of HEMA (2-hydroxyethyl methacrylate). JEndod 1996;22:244-248.

12. Gerzina TM, Hume WR. Effect of hydrostaticpressure on the diffusion of monomers throughdentin in vitro. J Dent Res 1995;74:369-373.

1 3. Hanks CT, Strawn SE, Wataha JC, Craig RG.Cytotoxic effects of resin components on cul-tured mammalian fibroblasts. J Dent Res

1 991;70:1450-1455.

14. Hanks CT, Wataha JC, Parsell RR, Strawn SE,Fat JC. Permeability of biological and syntheticmolecules through dentine. J Oral Rehabil1 994;21:475-487.

15. Lefebvre CA, Wataha JC, Bouillaguet S,Lockwood PE. Effects of long-term sub-lethalconcentrations of dental monomers on THP-1human monocytes. J Biomater Sci Polym Ed

1999;10:1265-1274.

16. Nakabayashi N, Pashley DH. Hybridization ofDental Hard Tissues. Chicago: Quintessence,1998.

5. Bouillaguet S, Wataha JC, Virgillito M, GonzalesL, Rakich D, Meyer JM. Effect of sub-lethalconcentrations of HEMA on THP-1 humanmonocyte-macrophages in vitro. Dent Mater2000;16:213-217.

6. Byers MR, Swif ML, Wheeler EF. Reactions ofsensory nerves to dental restorative procedures.Proc Finn Dent Soc 1992;88(suppl 1):73-82.

7. Ciucchi B, Bouillaguet S, Holz J, Pashley DH.Dentinal fluid dynamics in human teeth, in vivo.J Endod 1995;21:191-194.

8. Ciucchi B, Bouillaguet S, Jacoby T, Pashley DH.Bonding characteristics to dentin walls of ClassII cavities in vitro. Dent Mater (in press).

9. Davidson CL, Abdalla AI, De Gee AJ. An inves-tigation into the quality of dentine bonding sys-tems for accomplishing a durable bond. J OralRehabil 1993;20:291-300.

10. Erickson RL. Surface interactions of dentin ad-hesive materials. Oper Dent 1992;(suppl5):81-94.

11. Feilzer AJ, De Gee AJ, Davidson CL. Settingstress in composite resin in relation to configu-ration of the restoration. J Dent Res1987;66:1636-1639.

17. Pashley DH. Dentin-predentin complex and itspermeability: Physiologic overview. J Dent Res

1985;64(special issue):613-620.

18. Pashley DH. Dynamics of the pulpo-dentincomplex. Crit Rev Oral Biol Med 1996;7:104-133.

19. Pashley DH, Ciucchi B, Sano H, Horner JA. Per-meability of dentin to adhesive agents.Quintessence Int 1993;24:618-631.

20. Ratanasathien S, Wataha JC, Hanks CT,Dennison JB. Cytotoxic interactive effects ofdentin bonding components on mouse fibrob-lasts. J Dent Res 1995;74:1602-1606.

21. Sano H, Takatsu T, Ciucchi B, Horner JA,Matthews WG, Pashley DH. Nanoleakage:Leakage within the hybrid layer. Oper Dent1 994;20:18-25.

22. Tay FR, Gwinnet JA, Wei SHY. Variability in mi-croleakage observed in a total-etch wet-bond-i ng technique under different handling condi-tions. J Dent Res 1996;74:1168-1178.

23. Van Meerbeek B, Yoshida Y, Snauwaert J, et al.Hybridization effectiveness of a two-step versusa three-step smear layer removing adhesive sys-tem examined correlatively by TEM and AFM. JAches Dent 1999;1:7-23.

34

Chapter 3

Moisture Management withRubber Dam in Operative Dentistry

Karl-Heinz Kunzelmann

I ntroduction

The technology to isolate teeth underrubber dam and thereby eliminate adverseeffects of mouth humidity was first appliedin 1864 by the New York dentist S.C.Barnum. Subsequently, the use of rubberdam has made a substantial contributionto facilitating operative techniques andquality assurance, notably in endodonticsand adhesive restorative procedures.However, the gap between recommenda-tions and reality in the use of rubber damis wider than with any other technologyin dentistry. 4 While universities stoicallyteach the use of rubber dam, colleagues inpractice typically reject this technique. Themost frequently quoted arguments for notusing rubber dam relate to the time takento apply it and patient objection.

The rapid development of moderndentinal bonding and composite materialsand the widespread use of such systemsas an alternative to amalgam have broughtrubber dam back to the center of interestin recent years. The introduction of thecompomer Dyract (Dentsply, Konstanz,Germany), revived discussions about rub-ber dam, given that Dyract is the first resin-based material that does not require the

use of rubber dam in its application. Thisfeature of Dyract was a substantial reasonfor the high initial acceptance of com-pomers in the Federal Republic ofGermany. In addition, this feature resultedi n renewed consideration of the view thatrubber dam is a condition sine qua non inrelation to adhesive dentistry.

While the adherence to tooth substratesof early forms of adhesive restorative sys-tems may have been adversely affected byexhaled air humidity, this is difficult to com-prehend when considering modern hy-drophilic dentin bonding systems. Thecompomer matrix may be slightly more hy-drophilic than the matrix of hybrid com-posites given the availability of carboxylategroups in the compomer matrix.Compomers, however, are used togetherwith dentinal bonding agents almost iden-tical to those used with composites.Accordingly, it could be argued that allcomposites may be placed without the useof rubber dam. Eliminating the dogma thatrubber dam is a requirement for adhesivedentistry has stimulated debate regardingthe future role of rubber dam. However,considering the advantages of rubber dam(Table 3-1), it may be concluded that itgreatly facilitates adhesive procedures by

35

Moisture Management with Rubber Dam in Operative Dentistry

Table 3-1 Main arguments forthe use of rubber dam

Protection of the patient from

Dry, clear operating field

Protection of the soft tissues

I nfection control for patient, dentist, and chairside assistant

Possibilities for disinfecting the field of operation

aspirating or swallowing debris and small instruments

Table 3-2 Thickness of rubber (latex) dam mem-

keeping the operating field dry throughoutoperative procedures.

When working to a systematic scheme,rubber dam can be applied within 2 to 3minutes. Notwithstanding ergonomic ad-vantages, cost benefits may accrue fromthe use of rubber dam. A prerequisite forthe efficient, effective use of rubber dam isknowledge and experience of the relevanttechniques, linked to the ability to selectthe instruments, materials, and procedurefor placement best suited to particular sit-uations. 1-3,5,6

Material and Instruments

Rubber DamRubber dam membranes of different ma-terials are available in various thicknesses(Table 3-2), sizes, and colors.

36

Regarding which thickness of rubberdam to use, the guide is: the thicker thematerial, the better the isolation. However,thick rubberdam membranes place a highstress on the retainers for the dam, ie, therubber dam clamp. This is particularly ap-parent when isolating a molar tooth underrubber dam. Therefore, thin rubber dammembranes are recommended for the iso-lation of posterior teeth, reserving thickermembranes for use in the isolation of an-terior teeth. Alternatively, as has been theauthor's preference for many years, rubberdam membranes of "medium" thicknessmay be used throughout the mouth.When undertaking the chairside bleach-ing of teeth, however, "heavy" rubber damis recommended to best protect the gingi-val tissues from the bleaching solution.Rubber dam is available in rolls (eg, 150mm x 550 mm) or ready cut (eg, 150 mmx 150 mm). Since rubber dam is primari-ly used in combination with a rigid frame,ready-cut dam offers advantages.

The colors in which rubber dam is sup-plied include beige, gray, green, and blue.Beige rubber dam tends to be recom-mended for endodontics because it issomewhat transparent, allowing tooth po-sition and axis to be assessed during treat-ment. Green and blue rubber dam tends to


be used in adhesive dentistry procedures,given the color contrast with teeth. Whenusing such intensely colored rubber dam,however, it is important to record toothshade prior to isolation. Currently, there isa trend toward individually characterizedrestorations that are built up in incrementsof differently shaded composite materials.When applying this approach, the use ofgray rubber dam is indicated. Given the dif-ferent colors of rubber dam, it is possibleto work ergonomically by, for example,li nking color to the weight of dam (eg,green for medium, blue for heavy). In thisway, one can quickly select rubber dam ofappropriate thickness.

With the increasing use of rubber prod-ucts in medicine, there has been an in-creasing incidence of adverse reactions tol atex. Manufacturers of rubber dam havegiven consideration to this problem.Adverse reactions can be caused by thelatex or by materials used in the manu-facturing process. The powder used toseparate sheets of rubber dam duringproduction and storage contributes to thei ncidence of adverse reactions. Powder-free rubber dam has therefore been de-veloped ( Kentzer Kaschner Dental,Ellwangen/ Jagst, Germany). The powderi s removed by repeated washing. A furtherdevelopment is silcone-based, nonlatexrubber dam (Roeko, Langenau, Germany).A modified rubber dam punch that formslarger holes than the usual punch shouldbe used to compensate for the reducedelasticity of the silicone membrane.

Rubber Dam FrameThe rubber dam membrane is stretchedwith the help of a rubber dam frame.Different rubber dam frames are available

( Figs 3-1a to 3-1d). Rubber dam framesmay be metal or plastic. Plastic frames areradiolucent and are therefore suitable foruse in endodontic procedures involving ra-diographic examinations. However, theprongs of plastic frames are thicker thanthose of metal frames and, as a conse-quence, it may be relatively difficult to se-cure rubber dam to a plastic frame.

U-shaped frames have the advantage offi tting around the nose of the patient. It isincomprehensible that the manufacturersof oval-shaped rubber dam frames do notdirect the prongs of the frame away fromthe nose of the patient, given the occa-sional reference in the literature to traumafrom such prongs, which, in any case, tendto complicate rather than facilitate the ad-j ustment of the dam. One can solve thisproblem by removing prongs that maytraumatize the nose and inserting dentinalpins into the frame lateral to the nose.

I ts light weight, shape, and good damretention favor the routine use of the Youngframe in cases in which radiographs arenot required. In cases in which the use ofradiographs is anticipated, the Sauveurframe is recommended.

Rubber Dam PunchThe rubber dam punch is used to perfo-rate the dental dam. Two different types ofpunch are available. In the Ainsworthpunch (Fig 3-2a), the hinge is behind thetine and the rotating metal table. In theIvory punch (Fig 3-2b), the hinge is towardthe front. Having the hinge in front of thecutting table results in a circular, evenly cutperforation of the dam, thereby reducingthe risk of the dam tearing in use.

When using a rubber dam punch, it isimportant to ensure that the tine fits accu-

37


Figs 3-ia to 3-id Rubber dam frames.

Fig 3-1a Universal, U-shaped rubber dam frame.

Fig 3-1c Young U-shaped rubber dam frame.

Fig 3-1d Sauveur oval rubber dam frame.

Figs 3-2a and 3-2b Rubber dam punches.

Fig 3-2a The Ainsworth punch.

Fig 3-2b The Ivory punch.

Fig 3-1 b Nygaard-Ostby rubber dam frame.


Figs 3-3a and 3-3b The tine should be centered in the selected hole of the cutting table.

Fig 3-3a Incorrect centering. Fig 3-3b Correct centering.

Fig 3-4 Clean-cut hole (right), incomplete cut withresidual tag of dam (center), and irregular hole fol-l owing removal of residual tag (left).

rately into the selected hole in the cuttingtable (Figs 3-3a and 3-3b). If the tine doesnot fit accurately into the hole of the cuttable, the cutting edge of the hole can bedamaged, making a clean cut impossible.When the cut is incomplete and the resid-ual tag of rubber is torn off, the dam mayunexpectedly tear during placement (Fig3-4).

Rubber Dam Clamp ForcepsRubber dam clamp forceps differ in the de-sign of their distal tips (Fig 3-5). Forcepswith a stop machined into the distal tips( eg, Ivory) are distinct from forceps withplane distal tips (eg, Martin, Aeskulap).Distal tip stops have two advantages: Theyprevent the tips penetrating too deeply intothe rubber dam clamp and allow morecontrolled positioning of the clamp during

39


Fig 3-5 View of the distal tip of Ivory forceps. Thestop facilitates manipulation and placement of theclamp while minimizing trauma to the gingivae.

Table 3-3 Distinguishing features of rubber dam clamp types

placement. Forceps without distal tipstops may cause damage to gingivae if al-lowed to penetrate the clamp too deeply.All rubber dam clamp forceps have a lock-ing handle to allow the forceps to belocked in an open position, facilitatingclamp placement. Forceps are best lockedwith the minimum necessary opening. Thelocking handle should be held upwards sothat gravity works in the clinician's favor onrelease.

Rubber Dam ClampsRubber dam clamps retain the rubberdam. Clamps engage belowthe maximumconvexity of the tooth and thereby hold therubber dam in position. For stability, it is im-

portant for most clamps that they have op-timum contact with the tooth. If a clamphas two prong contacts on one side, butonly one contact on the opposite side, itwill tend to rotate or be displaced when thedam is tensioned.

While a small number of clamps candeal with most clinical situations, there isan almost incomprehensible range ofclamps available commercially. Clampsmay, however, be simply classified (Table3-3).

The decision to select winged or wing-less clamps depends on the applicationtechnique and the location of the tooth.Clamps without wings need less space,which, for example, can be favorable formaxillary molars, especially if the ascend-

40

Rubber Dam Application

Figs 3-6a and 3-6b Extraoral placement of a clamp (winged) in the dam. This technique allows placementof the rubber dam frame, membrane and clamp at the same time. It is especially helpful when isolating asmall number of teeth.

i ng part of the mandible interferes with theclamp. Winged clamps, on the other hand,provide extra retraction of the dam.Winged clamps are necessary if the damis to be applied as illustrated in Figs 3-6ato 3-6b.

The distance of the clamp bow to thedistal surface of the tooth is particularly im-portant when isolating the last tooth in anarch. Long clamps give better access butmay interfere with anatomic structures(eg, the ramus of the mandible). Longclamps therefore tend to be selected ifsingle teeth are to be isolated. For exam-ple, long clamps are indicated when usingthe intraoral camera of a Cerec system.

Clamp shape is dictated bytooth shape.The spacing between the prongs ofthe clamp jaws (contact zone) must belarger for molar teeth than for premolars(Figs 3-7a to 3-7f). Because of the sym-metrical shape of clamp jaws, the sameclamp can be used in either the left or theright side of the jaw. Maxillary molars fre-quently have a tapered shape, necessitat-i ng the selection of a clamp with jaws of dif-

ferent contact zone length. This, however,requires different clamps for left-and right-side use, as well as different-sized teeth.

Rubber dam clamps gain retention bybeing positioned belowthe maximum con-vexity of the tooth. Problems may thereforearise when isolating teeth that are brokendown or only partially erupted. In such sit-uations, rubber dam clamps with apicallydirected prongs are selected to gain reten-tion subgingivally (Fig 3-8).

Rubberdam clamps may be obtained insets (eg, Ivory Nos. 7, 8, 8A, 14A for molars;Nos. 0, 1, 2 for premolars; and No. 212 foranterior teeth), which are best stored in aclamp organizer (Fig 3-9).


PreparationStandardization of procedures is a prereq-uisite to the efficient, effective use of rub-ber dam. Preoperative preparation cansimplify various steps in the process. Thenecessary instruments (rubber dam

41


Figs 3-7a to 3-7f Rubber dam clamps.

Fig 3-7a

Rubber dam clamp No. 2 (with wings).

Fig 3-7b Wingless rubber dam clamp No. 2.This clamp is used for premolar teeth.

Fig 3-7c Rubber dam clamp No. 7. This clamp is

Fig 3-7d Clamp No. 14A. The prongs are directeddesigned for molar teeth.

gingivally, which is helpful, for example, with partial-l y erupted teeth.

Figs 3-7e and 3-7f Clamp Nos. 12A and 13B. The size of the buccal clamp jaw is larger than the lingualjaw. This facilitates placement on tapered teeth, for example, maxillary first molars.

42


Fig 3-8 Rubber dam clamps forbroken down and partially erupt-ed teeth have an additional curva-ture (A and B) to create apically di-rected prongs. The prongs areplaced between the gingival tis-sues and the tooth.

Fig 3-9 Rubber dam clamp organizer (Kentzer Kaschner Dental, Ellwangen/Jagst, Germany).

43


frame, rubber dam clamp forceps, rubberdam clamps, and rubber dam punch)should be at hand.

The rubber dam, together with associ-ated items, including tooth ligatures, rub-ber dam napkins, and lubricant (glyceringel), can be selected and prepared in ad-vance, as can tooth ligatures of dental floss(30 to 40 cm in length) stored rolledup on cotton-wool rolls. The rubber damcan be prepared for different situations.Positions for perforations can be markedon the dam preoperatively using a tem-plate and a water-resistant felt-tipped pen.Perforations may be cut for the three mostfrequent situations, ie, the isolation of allanterior teeth, a quadrant of posteriorteeth, and a single tooth.

For the isolation of anterior teeth, eightperforations should be cut in a semilunararc according to the template for 14 to 24.Contrary to traditional teaching to includeonly the tooth to be treated together withthe two adjacent teeth, current practice isto isolate a segment of teeth. When treat-i ng anterior teeth, the reason for this is thatrubber dam can be reliably anchored withthe help of the rubber dam clamps on pre-molar teeth. In such situations, all eightperforations should be formed using thesecond smallest hole of the Ivory punch.

For posterior teeth, the rubber damclamp is best placed on the tooth distalto the tooth to be treated. For premolarsthe second smallest hole and for molarsthe next larger hole of the Ivory punchshould be selected. If additional perfora-tions are necessary, they are included atthe chairside. Perforations need only beprepared for one quadrant because thedam maybe oriented for all four quadrants.The small difference between the curva-ture of maxillary and mandibular jaws is

compensated for by the elasticity of thedam.

I n endodontics, usually only one perfo-ration is necessary for the isolation of asin-gle tooth.

Application TechniqueMany different application techniques aredescribed and taught, with selection de-pending on personal preference. It is pos-sible to work successfully with one of anumber of techniques, which differ ac-cording to the timing of the placementof clamp and frame. The clamp may beplaced first and the dam stretched over theclamp and then attached. Alternatively, theclamp can be placed in the dam and thenplaced around the tooth priorto stretchingthe dam around the frame (Fig 3-9). Theauthor prefers a further variation in whichthe membrane is stretched overthe rubberdam frame and then over the tooth prior toplacing the clamp.

I rrespective of the application tech-nique, the following may be of assistance:Before rubber dam is placed, it should bedetermined whether dental floss can passthrough the proximal contact. If it is notpossible to pass dental floss througha proximal contact, rubber dam will notpass through the contact. If this occurs, itmay be necessary to renew a filling or sep-arate the teeth with a wooden wedge.Alternatively, it may be decided to excludethe contact in the isolation. It is also pru-dent to check the retention of the rubberdam clamp prior to placing the rubberdam.

Rubber dam passes through proximalcontacts more easily if it is lubricated. Thelubricant should not contaminate cavitiesand must therefore be water soluble.

44


Figs 3-10a to 3-10p Placement of rubber dam.

Fig 3-10a Dental floss is passed through theproximal contacts to identify potential problems pri-orto placing the rubber dam membrane.

Fig 3-10b The rubber dam is punched and fixedto the frame. The membrane is lubricated aroundthe holes on the oral surface.

Fig 3-10c The rubber dam membrane is strechedwith the index fingers to see the tooth on to whichthe dam will first be placed.

Fig 3-10d The rubber dam membrane is slidover the tooth.

Petroleum jelly, which is occasionally rec-ommended, should not be used. An ex-ample of an appropriate water-soluble lu-bricant is glycerin gel (Air block, Dentsply,Konstanz, Germany).

The lower lip frequently gives rise to dif-ficulties when applying rubber dam be-cause it may be pressed against themandibular anterior teeth when the mouth

is opened. Inserting a cotton roll into themandibular anterior sulcus can createspace to accommodate the rubber dambetween lip and teeth. The cotton roll is leftin the sulcus during treatment.

The step-by-step application and re-moval of rubber dam is illustrated inFigs 3-10a to 3-10p.

4 5


Fig 3-10e The index finger of the leading handis replaced by a dental mirror.

Fig 3-10g Alternatively, rubber dam is held inposition on the arch with the index and middle fin-gers of the nonleading hand if the operator has towork without assistance.

Fig 3-10i The dam is secured with the clamps.Now the membrane is passed through the contactpoints.

46

Fig 3-1 Of The clamp is placed with the rubber damforceps. The palatal jaw of the clamp is positionedfirst and kept in constant contact with the tooth. Thebuccal jaw of the clamp is then positioned.

Fig 3-10h The second retainer is placed. Note thatthe middle finger stabilizes the palatal jaw of theclamp that is positioned first.

Fig 3-10j Dental floss can be used to pass themembrane through tight contacts points. It is im-portantto start on one side and work around, pullingthe dam apically.


Fig 3-10k As the membrane is pulled, it gets thin-ner and follows the dental floss. The floss is then re-moved buccally.

Fig 3-101 This procedure is repeated, passing thedam through consecutive contacts.

Fig 3-10m Rubber dam is inverted to complete theseal around the tooth. This is best accomplished in-terproximally with dental floss and buccally and lin-qually with a blunt instrument, eq, a beaver-tail bur-

Fig 3-10n Dental floss ligatures help to keep therubber dam close to the gingival tissues.

Fig 3-10o For the rubber dam to be removed, firstthe ligatures have to be cut. Using a scaler helps toavoid injuring the gingival tissues because it is usu-ally difficult to cut a tight ligature with scissors.

Fig 3-10p The dam septa are cut with scissorswhile the rubber dam is pulled away from the gingi-val tissues and the tooth. Use dental floss to removeany rubber dam remnants.

47


Summary

Rubber dam facilitates the efficient, efftivecompletion of operative procedures. Theapplication of rubber dam should not takemore than 3 to 4 minutes. If circumstancespreclude the placement of rubber dam insuch a short period of time, one should

consider other forms of isolation, includingcotton rolls, cellulose pads, or retractioncords combined with high-volume suctionor saliva ejectors. The benefits to the oper-ator and patient of using rubber dam in-clude the opportunity to undertake treat-ment in a controlled, relaxed manner.

References 4. Marshall K, Page J. The use of rubber dam in theUK. A survey. Br Dent J 1990;169:286-290.

1. Liebenberg WH. Extending the use of rub-ber dam isolation: Alternative procedures. PartI . Quintessence Int 1992;23:657-665.

2. Liebenberg WH. Extending the use of rub-ber dam isolation: Alternative procedures. PartII. Quintessence Int 1993;24:7-17.

3. Liebenberg WH. Extending the use of rub-ber dam isolation: Alternative procedures. PartIII. Quintessence Int 1993;24:237-244.

5. Wilder A, May KN, Strickland WD. Isolation ofthe operating fi eld. I n: Sturdevant CM,Robertson TM, Heymann HO, Sturdevant JR.The Art and Science of Operative Dentistry. St.Louis: Mosby, 1995.

6. Winkler R. Kofferdam in Theorie and Praxis.Berlin: Quintessenz, 1991.

48

Chapter 4

Tissue and Moisture Managementi n Operative Dentistry

Stefano Patroni

I n the last 20 years, biological aspects ofrestorative dentistry have received a greatdeal of attention. This attention emanatedfrom the experimental work of theScandinavian periodontal research com-munlty.

3,17,18,35,36 This work challenged

some therapeutic dogmas, including theprinciple of "extension for prevention" pro-moted by G.V. Black , 4 which dominatedrestorative dentistry for almost a century.Subsequently, many reviews have stressedthe necessity for more biological thinkingand the need for the revision of old-fash-i oned, mechanistic approaches to oralhealth care.

Achieving periodontal health some-times seems diametrically opposed tothe requirements of restorative dentistry.The mechanical prerequisites of occlusalreduction and length of preparation aremore predictably managed when themargin of the restoration can be plac-ed supragingivally. However, interocclusalspace limitations, previous hard tissue de-struction, esthetic considerations, ex-posed margins, and "black triangles" cancreate a great challenge for the restorativedentist. 14

It is well-known that periodontal dam-age may occur during the restorative

phase of treatment (Figs 4-1 to 4-3).Atraumatic manipulation of the periodontaltissues during retraction, tooth preparation,provisionalization, and the recording of fi-nal impressions are the keys to predictabletissue control and biologic integrity (Figs 4-4 to 4-7).

I t is important to be aware that theposition of the crown margin in relation tothe gingiva can significantly affect theGingival Index value as well as the gingivalsulcus depth . 2,23,26,27,32 Subgingivally po-sitioned crown margins are associatedwith the highest Gingival Index values,whereas supragingivally located crownmargins are associated with the lowest val-ues.23

In their studies, Renggli and Mor-mann20,24 concluded that during cavityor crown preparation margins should beplaced supragingivally whenever possibleand restoration margins that have beenplaced subgingivally should be exposed.Valderhaug 30,31,33,34 showed that loss ofthe periodontal supporting apparatus wasgreater around teeth restored with subgin-givally located crown margins than it wasaround those with crown margins locatedsupragingivally. Other authors 13,15,25 claim,however, that a precise marginal crown fit

49

Tissue and Moisture Management in Operative Dentistry

Figs 4-1 to 4-3 Following the "hygenic phase" oftreatment, it is possible to prepare the tooth withoutdamaging the periodontal tissues.

seems to be the prerequisite for the stabil-i ty of the periodontal tissues around abut-ment teeth.

Valderhaug and Heloe34 found that thei ncidence of caries is increased whenrestoration margins are located subgingi-vally. Lang et a1 1 6 documented that, fol-lowing the placement of restorations withoverhanging margins, a subgingival florathat closely resembles that of chronic peri-odontitis may be detected . Thus, it is pos-sible to conclude that there is no biologicreason to locate restoration margins sub-gingivally, only esthetic reasons.

Whenever restoration margins invadethe periodontal attachment they violate

50

the biologic width 7,19,29 and cause dam-age to the periodontium, which results inloss of attachment.

Therefore, each time that it is necessaryto restore a tooth that presents deep sub-gingival caries (Figs 4-8 and 4-9); a rootfracture; root resorption or perforation;preexistent deep, subgingivally locatedpreparation margins; or a short clinicalcrown, consideration should be given tosurgical crown lengthening and/or forcedorthodontic eruption9,10,28 to avoid anyimpingement upon the biologic width.

Surgical crown lengthening has beendescribed as a procedure similar to anapically repositioned flap with concomitant


Figs 4-4 and 4-5 A further example of atraumatic manipulation of the periodontal tissues. No bleeding ispresent following retraction and tooth preparation.

Figs 4-6 and 4-7 After 4 weeks, at the time of the try-in of the casting, it is possible to observe the preser-vation of tissue health.

Figs 4-8 and 4-9 Radiographic examination reveals a deeply located lesion of caries in the distal aspectof 36. It is evident that it will only be possible to restore the tooth after a surgical crown-lengthening proce-dure.

51


Fig 4-10 Tooth 45 presents a short clinical crown.Tooth 46 includes a deep cavity invading the peri-odontal attachment.

Fig 4-11 Flap design: a partial4ull-partial-thick-ness flap is elevated.

Fig 4-12 Measurement of the distance betweencavity margin and the bony crest.

Fig 413 The root form and an exostosis are evi-dent lingually.

ostectomy and osteoplasty. 1.6,11,12,22

Proper flap design is an essential elementof the surgical procedure (Figs 4-10 to4-13), which generally involves a partial-full-thickness flap that can be extended toa partial-full-partial-thickness positionedflap.8 The flap is scalloped and the newlycreated papillae are thinned to a thicknessof approximately 1.5 mm. Following bonycontouring, the flap is repositioned at thelevel of the bone margin or more apicallythrough the use of periosteal vertical orhorizontal mattress sutures (Figs 4-14 to4-17).

Healing following osseous crown-lengthening surgery results in a junctionalepithelium that extends to the apical levelof the root planing. 21 Postsurgical resorp-tion of the osseous crest creates space forsupracrestal connective tissue. 21 A re-duced apically relocated biologic width isreestablished following crown-lengthen-ing surgery as reported by Caton andNyman. 5 After a period of 3 to 6 months oftissue maturation, it is possible to performthe planned restorative procedures with-out violation of the biologic width (Figs4-18 to 4-21, 4-22 and 4-23).

52


Fig 4-14 The bony architecture after osteotomyand osteoplasty.

Fig 4-15 The surgical measurement of the dis-

tance between the cavity margin and the bonel evel after osteotomy.

Fig 4-16 The lingual aspect of the surgical fieldafter osteotomy and osteoplasty. The root of 45

was prepared distallyto create more space between45 and 46.

Fig 4-17 The flap is positioned adjacent tothe bone level using vertical periosteal mattresssutures.

Fig 4-18 The buccal aspect 5 months after surgery. Fig 4-19 The lingual aspect 5 months aftersurgery.

5 3


Figs 4-20 and 4-21

The integrity of the periodontium has not been violated by the careful placementof the margin of the metal ceramic crown on 45.

Fig 4-22 Bioesthetic, intracrevicular metal ceramic

crowns

on

maxillary

central

i ncisors.

The

by the placement of the metal ceramic crowns.adjacent periodontal tissues are preserved despitethe intracrevicular placement of the crown margins.

Fig 423 The biologic width has not been violated

5 4

References

References

1. Baima RF. Extension of clinical crown length.J Prosthet Dent 1986;55:547-551.

2. Bergman

B,

Hugoson

A,

Olsson

CO.Periodontal and prosthetic conditions in pa-tients treated with removable partial denturesand artificial crowns. Acta Odontol Scand1971;29:621-638.

3. Bjorn AL, Bjorn H, Grkovic B. Marginal fitof restorations and its relation to periodontalbone level I. Metal fillings. Odontol Revy 1969;20:311-321.

4. Black GV. A Work on Operative Dentistry. Vol 1:The pathology of the hard tissues of the teeth.Chicago: Medico-Dental, 1908:142-144.

5. Caton J, Nyman S. Histometric evaluation ofperiodontal surgery. III. The effect of bone re-section on the connective tissue attachment lev-el. J Periodontol 1981;52:405-409.

6. Davis JW,

Fry HR,

Krill

DB,

Rostock M.Periodontal surgery as an adjunct to endodon-tics, orthodontics, and restorative dentistry. JAm Dent Assoc 1987;115:271-275.

7. Gargiulo A, Wentz F, Orban B. Dimensions andrelations of the dentogingival junction in hu-mans. J Periodontol 1961;32:261-267.

8. Goldman HM, Shuman A, Isenberg G. An Atlasof the Surgical Management of PeriodontalDisease. Chicago: Quintessence, 1982.

9. Ingber JS. Forced eruption. I. A method of treat-i ng isolated one and two wall infrabony osseousdefects-Rationale and case report. JPeriodontol 1974;45:199-206.

10. Ingber JS. Forced eruption: Part II. A methodof treating nonrestorable teeth-Periodontal andrestorative considerations. J Periodontol 1976;47:203-216.

11. Ingber JS, Rose LF, Coslet JG. The "biologicwidth"-A concept in periodontics and restora-tive dentistry. Alpha Omegan 1977;70:62-65.

1 2. Kaldahl WB, Becker CM, Wentz FM. Periodontalsurgical preparation for specific problems inrestorative dentistry. J Prosthet Dent 1984;51:36-41.

13. Kerschbaum T, Meier F. Individual differences inthe marginal periodontium of crowned and non-crowned topographically identical teeth [inGerman]. Dtsch Zahnarztl Z 1978;33:499-504.

14. Kois JC. The restorative-periodontal interface:biological parameters. Periodontol 20001996;11:29-38.

15. Koivumaa KK, Wennstrom A. A histologicali nvestigation of the changes in gingival marginsadjacent to gold crowns. Odontol Tidskr1960;68:373-385.

16. Lang NP, Kiel RA, Anderhalden K. Clinical andmicrobiological effects of subgingival restora-tions with overhanging or clinically perfect mar-gins. J Clin Periodontol 1983;10:563-578.

17. Lindhe J, Wicen PO. The effects on the gingi-vae of chewing fibrous foods. J Periodontal Res1 969;4:193-200.

1 8. Lee H. Reaction of marginal periodontaltissues to restorative procedures. Int Dent J1 968;18:759-778.

1 9. Maynard JG, Wilson RD. Physiologic dimen-sions of the periodontium significant to therestorative dentist. J Periodontol 1979;50:1 70-174.

20. Mormann W, Regolati B, Renggli HH. Gingivalreaction to well-fitted subgingival proximal goldi nlays. J Clin Periodontol 1974;1:120-125.

21. Oakley E, Rhyu IC, Karatzas S, Gandini-SantiagoL, Nevins M, Caton J. Formation of the biologicwidth following crown lengthening in nonhuman primates. Int J Periodontics RestorativeDent 1999;19:529-541.

22. Palomo F, Kopczyk RA. Rationale and methodsfor crown lengthening. J Am Dent Assoc1978;96:257-260.

23. Reichen-Graden S, Lang NP. Periodontal andpulpal conditions of abutment teeth. Status afterfour to eight years following the incorporation offixed reconstructions. Schweiz MonatsschrZahnmed 1989;99:1381-1385.

24. Renggli HH. The effect of subgingival cervicalrestoration margins on the degree of inflamma-tion of the neighboring 21 gingiva (a clinicalstudy) [in German]. SSO Schweiz MonatsschrZahnheilkd 1974;84:1-18.

55


25. Richter WA, Ueno H. Relationship of crownmargin placement to gingival inflammation. JProsthet Dent 1973;30:156-161.

26. Silness J. Periodontal conditions in patientstreated with dental bridges. J Periodontal Res1970;5:60-68.

27. Silness J. Periodontal conditions in patientstreated with dental bridges. IV. The relationshipbetween the pontic and the periodontal condi-tion of the abutment teeth. J Periodontal Res1974;9:50-55.

31. Valderhaug J. Periodontal conditions and cari-ous lesions following the insertion of fixed pros-theses: A 10-year follow-up study. Int Dent J

1 980;30:296-304.

32. Valderhaug J. Margin of restorations-From theviewpoint of crown and bridgework making. NorTannlaegeforen Tid 1972;82:386-390.

33. Valderhaug J, Birkeland J. Periodontal condi-tions in patients 5 years following insertion offixed prostheses. Pocket depth and loss of at-tachment. J Oral Rehabil 1976;3:237-243.

28. Sterr N, Becker A. Forced eruption: Biologicaland clinical considerations. J Oral Rehabil1 980;7:395-402.

34. Valderhaug J, Heloe LA. Oral hygiene in a groupof supervised patients with fixed prosthesis. JPeriodontol 1977;48:221-224.

29. Vacek JS, Gher ME, Assad DA, RichardsonAC, Giambarresi LI. The dimensions of the hu-man dentogingival junction. Int J PeriodonticsRestorative Dent 1994;14:154-165.

30. Valderhaug J. A 15-year clinical evaluation offixed prosthodontics. Acta Odontol Scand1991;49:35-40.

35. Waerhaug J. Histologic considerations whichgovern where the margins of restorationsshould be located in relation to the gingiva. DentClin North Am 1960;4:161-176.

36. Waerhaug J. Tissue reactions around artificialcrowns. J Periodontol 1953;24:172-185.

56

Chapter 5

Esthetic Anterior Restorations

Jean-Frangois Roulet and Roberto Spreafico

I ntroduction

The rate of development of materials andapplication techniques in the last 15 yearshas enabled the dentist to fulfill the highestesthetic requirements of our patients,ie, to place "invisible" or imperceptiblerestorations. Dentists can produce natural-looking restorations that comply withGarber's maxim: "The game is to make theartificial look natural" (Garber DA, person-al communication, 1989). The result ofthese developments is that the dentist canrestore teeth following the principle ofminimal invasiveness, ie, maintaining asmuch sound tooth tissue as possible. Afew examples demonstrate the possibili-ties:

Patient 1 (Figs 5-1 ato 5-1 d): This patientwas bothered with diastemata, which de-veloped following periodontal treatment.Using enamel bonding techniques, theshape of the teeth was changed to makethem larger and to close the diastema(treated by Dr. S. Herder).

brought along one fragment; the pulp wasexposed. After direct pulpal capping, thefragment was bonded to the remainingtooth and the missing fragment recon-structed with composite (treated by Prof.M. Degrange).

Patient 3 (Figs 5-3a to 5-3e): Followingtrauma, the incisal edge of tooth 21 was re-constructed with composite in 1991. Nineyears later a second blow displaced thetooth approximately 1 mm palatally, andpulp necrosis and discoloration followed.Root canal treatment failed despite a sat-isfactory initial oucome; therefore, anapicectomy was performed. After therestoration was appropriately placed, it re-flected the color shift of the tooth (Fig 5-3d). After bleaching, the tooth had thesame color as the adjacent teeth. In addi-tion, the restoration had undergone achameleon-type color shift.

Progress inMaterials Development

Patient2(Figs 5-2ato 5-2f): This 11-year-old girl fell from her bicycle and fracturedthe incisal edge of tooth 11. The parents

With the introduction of light-curing tech-nology,2,6 the color of composites becamevery stable because the initiator system no

5 7


Figs 5-ia to 5-1d Patient 1 (courtesy of Dr. S. Herder).

Fig 5-1a

Diastema after periodontal treatment

Fig 5-1b Diastema after periodontal treatment (left(right side).

side).

Fig 5-1c After reconstruction with composite and

Fig 5-1d Side view.adhesive technique. Note that the teeth were not ve-neered; composite was added only to the proximalsurfaces.

58

Progress in Materials Development

Figs 5-2a to 5-2f Patient 2 (courtesy of Prof. M. Degrange).

Fig 5-2a Eleven-year-old girl after bicycle accident.

Fig 5-2b Isolation of the operative field with rubberI ncisal edge of tooth 1 1 is severely fractured.

dam.

Fig 5-2c

Direct pulpal capping with calcium hy-

Fig 5-2d A fragment was bonded to the remainingdroxide cement.

tooth tissues. The remaining defect was recostruct-ed with composite.

Fig 5-2e Postoperative view.

Fig 5-2f After 1.5 years.

59


Figs 5-3a to 5-3e Patient 3.

Fig 5-3a Patient in 1991 follow-i ng reconstruction.

Fig 5-3b Close-up view of recon-struction. The finishing line is justvisible.

Fig 5-3c Root canal treatment af-ter palatal dislocation of the tooth,which was followed by pulp necro-sis (2000).

Fig 5-3d Situation after apicectomy. The tooth isdiscolored. Note that the restoration is indistin-guishable.

Fig 5-3e Same tooth after bleaching. Note that it isalmost the same color as the adjacent teeth and thatthe restoration is still indistinguishable.

60

Basic Principles for the Provision of Esthetic Anterior Restorations

longer decomposed into colored (brownor yellow) compounds. 9 Furthermore,once chairside mixing was eliminated, thematerials were almost free of voids,10which minimized pigment trapping in thematerial's surface. Light curing substan-tially reduced the polymerization time,which opened the way for the layeringtechnique to become a cornerstone in theprovision of esthetic restorations. In thelate 1980s, manufacturers had started toproduce composites in both different col-ors and different opacities (Herculite,Kerr; Tetric Ceram, Vivadent, Schaan,Liechtenstein; Enamel Plus H FO,Micerium srl, Italy; Esthet!X, Dentsply,Konstanz, Germany), which made the es-thetic qualities of a restoration more pre-dictable. In the last 20 years, the filler tech-nology forcomposites has been greatly im-proved. Modern small-particle hybridcomposites show stable optical surfacecharacteristics that are close to those ofenamel.11

Progress inAdhesive Technology

Following the introduction of the enameletching technique by Buonocore,l it wasmany years until well-defined applicationprocedures and principles were deter-mined and then widely applied in dailydental practice.3,8 Based on this research,i t was apparent that to obtain optimal mar-ginal morphology, bevels had to be placedi n enamel margins. Furthermore, it be-came clear that enamel unsupported bydentin did not have to be removed, as isthe case with classical, nonadhesiverestorative techniques. This opened theway for the preservation of buccal enamel

in proximal proportions, thereby minimiz-ing the visible portion of the restorationand improving esthetic outcomes.

I n the early 1980s, manufacturers be-gan to market dentin adhesives. However,only once the basic principles were thor-oughly understood 5 was reliabilityachieved. With today's dental adhesives iti s possible to obtain a micromechanical re-tention in dentin with various applicationtechniques.

Basic Principles for theProvision of EstheticAnterior Restorations

A natural tooth shows many differentfeatures (Fig 5-4), that should be mimickedin a natural-looking restoration. In naturalteeth, the color comes from within, notfrom the surface (Figs 5-5, 5-6a, and 5-6b).I t is therefore necessary to replace dentinwith an opaque "dentin-composite" andenamel with a more transparent/translu-cent "enamel-composite." Special effectscan be obtained in the incisal area usingtransparent composites. This approachforms the basis of the layering concept foranterior restorations (Figs 5-7a to 5-7h).There is a simple way to understand theopacities of different composite materialsand their use in creating natural-lookingrestorations. Take an impression of thepalatal aspect of an extracted incisor. Usethis form to produce a composite toothusing the layering technique (Figs 5-8a to5-8f).

An enamel bevel with no definite finish-i ng line is very important to achieve opti-mal esthetics (Fig 5-9). It creates a contin-uous transition from the tooth color into thecomposite color, which never matches the

61


Fig 5-4 Natural incisor. Note the optical features:Cervically the color is darker and more brownish/or-ange than in the body portion. In the incisal area theenamel appears bluish because of the dark back-ground of the oral cavity shining through. The incisaledge is shiny yellow because of light reflections inthe almost transparent enamel. Also visible are themamelons, which are dentinal protuberances thattaper toward the incisal edge, shining through theenamel. This tooth has some white stria in its bodyand a white spot in the incisal (courtesy of Dr. G.Losche).

Fig 5-5

Cross section of an anterior tooth illumi-nated by a laser beam. Note that the light penetratesthe enamel layer and is then dispersed in the dentin,immediately under the transparent limiting dentinallayer and next to the dentinoenamel junction.Therefore, the color of the natural tooth comes morefrom the dentin than from the enamel (surface)( courtesy of Dr. G. Losche).

62


Figs 5-6a and 5-6b Incisor with all the palatal enamel and a large amount of the dentin removed.

Fig 5-6a In transmitted light the tooth appears tool i ght because the dentin, which contributes most tothe tooth color, is missing.

Fig 5-6b In reflected light the tooth seems to be toodark because of the dark background of the oralcavity.

tooth color exactly. Therefore, the eye isdeceived because it is best suited to per-ceive discrete changes (eg, a black line ona white background). If color changes aregradual, the eye has difficulty detectingthem.

Finally, there is a phenomenon that mayoccur if a simple mistake is committed.Usually bonding agents are very transpar-ent because they are unfilled. If such abonding agent is applied in a thick layer( Fig 5-10), it may create a gray hue alongthe margin of an otherwise perfect restora-tion, which will then be visible (Fig 5-11). Ameans of preventing this phenomenon istouse a filled, tooth-colored bonding agent.

The human eye is also good at discern-i ng structures. Therefore, one must in-clude in the restoration the macro and mi-cro surface features of natural teeth if therestoration is to blend into the surroundingtooth tissues. Such structures are createdwith diamond burs. Final polishing is then

accomplished with the Occlubrush (HaweNeos, Switzerland).

A clinical case is illustrated in Figs5-12a to 5-12i to demonstrate in detail thesequence of placing anterior restorations.

This 55-year-old female patient wishedto have the appearance of her upper ante-rior teeth improved. The best option to ful-fill the patient's esthetic expectationswould be the provision of six ceramic ve-neers or crowns extending from canine tocanine. Unfortunately, the patient couldnot afford such treatment and she decid-ed to have the existing composite restora-tions in the central and lateral incisors andi n the canines replaced. In this way, imper-ceptible restorations may be placed in an-terior teeth. The challenge is to integratethe restorations with the remaining dentaltissues. The difficulty lies (especially withthe lateral incisor) in replicating the differ-ent colors evident in the remaining toothtissues.

63


Figs 5-7a to 5-7g Layering technique for anterior restorations.

Fig 5-7a Preoperative view of a central incisori ncluding an unesthetic white spot. To be as con-servative as possible, careful removal of the whitespot and a direct composite restoration wasplanned.

Fig 5-7b Two layers of composite, one enamel andthe other transparent, were layered on the spatulato check the color matching.

Fig 5-7c The cavity is prepared. Because the prepa-ration is contained in enamel, an enamel-coloredand transparent composite will be required.

Fig 5-7d The initial increment of composite isplaced and contained prior to light curing.

64


Fig 5-7e Some white stain is placed in the contours

Fig 5-7f The restoration is completed with a layerof the initial increment and polymerized to replicate

of transparent composite, contouring, and finishing.the white lines present in the adjacent tooth.

Figs 5-7g and 5-7h The restored tooth 2 weeks later. Note the good esthetic integration of the restorationwith the surrounding tissues, the adjacent tooth, and the oral environment.

65


Figs 5-8a to 5-8f An exercise inthe application of the layeringtechnique: the step by step pro-duction of a composite tooth.

Fig 5-8a A good exercise inlearning how to layer composite isto produce a composite tooth. Asilicon mold is obtained from anatural tooth. An initial thin layer ofa translucent composite is placedin the palatal aspect of the siliconmold and light cured.

Fig 5-8b The composite shell isremoved from the silicon mold.

Fig 5-8c An opaque dentin com-posite is layered in the transparentshell; mamelons are created asfound in an intact tooth.

66


Figs-8f Afterfinishing, microfea-tures are created in the surface us-ing a diamond bur. The tooth iscompleted by polishing.

67

Fig 5-8d It is very importantto layer the dentin composite witha varying thickness. In the intacttooth, dentin is thickest in the cer-vical region, relatively thin in themiddle of the tooth, and absent inthe incisal region.

Fig 5-8e A layer of enamel com-posite is applied over the dentin,l eaving the incisal portion and lim-iting layer to be formed of translu-cent composite.


Fig 5-9 The importance of a bev-el for esthetics. A bevel creates agradual transition between thecolor of the tooth and the color ofthe composite, which never exact-ly match. In this way the eye is de-ceived to perceive good esthetics.

Fig 5-10 If a clear, transparentbonding resin is used, it must beapplied in a thin layer, otherwisethe restoration will have a grayhue to the finishing line.

Fig 5-11 Two Class III restora-tions in tooth 22. The mesialrestoration is visible despite per-fect morphology. This is causedby a thick layer of bonding resincreating a gray hue along the fin-i shing line. The distal restorationblends in perfectly with the colorof the tooth.

68


Figs 5-12a to 5-1211 Step-by-step illustration of a clinical case.

Fig 5-12a Preoperative view of teeth 21,22, and 23requiring replacement composite restorations as aconsequence of secondary caries and poor esthet-i cs. Because the shape of 22 was judged to be ac-ceptable, a silicon guide was obtained to facilitatethe restoration of this tooth.

Fig 5-12b Following cavity preparation and priortorubber dam placement, composite shades are test-ed on the tooth to confirm the color matching. Anenamel composite is layered over a more opaquedentinal shade to confirm shade selection.

Fig 5-12c Following the application of rubber dam,cavity preparation is completed.

Fig 5-12d The previously prepared silicon guide isapplied palatally. The guide seems to restore theform of the tooth. An initial layer of enamel com-posite (shade A3) is applied to the silicon stent andthe margins of the preparations. Following light cur-i ng of the initial increment of composite, the stent isremoved.

6 9


Fig 5-12e A dentin composite (shade A 3.5) is lay-ered in the cervical area of the tooth (22) and in theother Class III preparations.

Fig 5-128 The clear matrix band is applied andsecured with a wooden wedge to build up the prox-i mal surface. Two increments of enamel composite(shade A3 cervically and A2 coronally) are applied.

70

Fig 5-12f The Class III restorations are completedwith a layer of enamel composite (shade A3).Further incremental layers of dentinal composite

(shades A3 cervically and A2 incisally) are placed intooth 22.

Fig 5-12h The restored teeth after finishing andpolishing. The restorations appear darker becauseof the dehydration of the remaining tooth tissues.With dehydration enamel becomes more opaqueand lighter.

Fig 5-121 The restored teeth 1 month later. Therestorations are fully integrated with the surroundingdental tissues.

Conclusions

Conclusions

the provision of imperceptible, long-lastingrestorations demands a high degree of

With modern composites and the applica-

skill and considerable time and effort, withtion of the techniques described in this

significant cost consequences in relationchapter, it is possible to place impercepti-

to the fees for the treatment. Intheabsenceble restorations that satisfy the most de-

of suitable remuneration, as is common inmanding esthetic requirements and pa-

nationally funded schemes in manytient expectations. Furthermore, existing

countries in Europe, it is impossible toliterature indicates that such restorations

provide restoration of the type describedmay have excellent longevity.4 However,

to every patient.

71


References

1. Buonocore MG. A simple method of increasingthe adhesion of acrylic filling materials to enam-el surfaces. J Dent Res 1955;34:849-853.

2. Dart EC, Nemcek J [inventors]. Photo-polymerizable composition. Brit patent B 1 408265. 1 Oct 1975.

3. Lutz F, Luscher B, Ochsenbein H, MuhlemannHR. Adhasive Zahnheilkunde. Zurich: Zahnarzt-li ches Institut, 1976.

4. Manhart J, Hickel R. Longevity of restorations.I n: Wilson NHF, Roulet J-F, Fuzzi M (eds).Operative Dentistry. Vol 2: The challenge of thefuture. Berlin: Quintessence, 2001 (in press).

5. Nakabayashi N, Kojima K, Masuhara E. Thepromotion of adhesion by the infiltration ofmonomers into tooth substrates. J BiomedMater Res 1982;16:265-273.

6. Osborn CL, Trecker DJ [inventors]. Photo-polymerization process using combinations oforganic carbonyls and amines. US patent3:759-807. 18 Sept 1973.

7. Perdigao J, Lopes M. Dentin bonding-Questions forthe new millennium. J Adhes Dent

1999;1:191-209.

8. Porte A, Lutz F, Lund MR, Swartz ML, CochranMA. Cavity designs for composite resins. OperDent 1984;9:50-56.

9. Roulet J-F. Degradation of Dental Polymers.

Basel: Karger, 1987.

10. Roulet J-F, Besangon H. Porosity of composites[i n German]. SSO Schweiz MonatsschrZahnheilkd 1983;93:953-959.

11. Willems G, Lambrechts P, Braem M, Celis JP,Vanherle G. A classification of dental compos-ites according to their morphological and me-chanical characteristics. Dent Mater 1992;

8:310-319.

72

Chapter 6

Direct Posterior Restorations-Techniques for Effective Placement

Guido Goracci

I ntroduction

Silver amalgam has for many years beenthe restorative material of primary impor-tance in conservative dentistry. In additionto favorable clinical properties and ease ofuse, dental amalgam is versatile and eco-nomical in use. However, the introductionof esthetic restorative materials with en-hanced properties, together with recentcontroversies concerning the toxicity ofmercury, have resulted in a reevaluation ofthe role of amalgam in everyday clinicalpractice. This reevaluation has resulted incurrent composite resins being viewed assubstitutes for amalgam in the provision ofdirect restorations in posterior teeth.20,23

Advances in CompositeRestorations

Restorations composed of early forms ofcomposite resins had two principalproblems: poor wear resistance limitingtheir use to anterior locations in non-load-bearing situations (Fig 6-1) andlack of adhesion to dental structures. 1,2,4

I n addition, marked polymerizationshrinkage resulted in marginal gap for-mation and bacterial leakage (Figs 6-2

and 6-3) with a high risk of recurrentcaries. 14

Contemporary hybrid composites withhigh levels of filler loading have, in con-trast, good wear resistance and excellentmechanical properties. 3 Problems relatedto the excessive occlusal wear of com-posite restorations under occlusal loadinghave been largely eliminated. To overcomeproblems of marginal gap formation andmicroleakage associated with the poly-merization contraction of composite re-sins, 14 new bonding systems with highbond strengths to dentin have been devel-oped. These systems allow for the simul-taneous etching of dentin and enamel( Figs 6-4 and 6-5) with the removal of thesmear layer ("total etching") (Figs 6-6 to 6-8), creating opportunity for micromechan-ical bonding to enamel and chemical mi-cromechanical bonding to dentin (Figs 6-9 to 6-15). 18 The chemical bond to dentinis mediated by the bifunctional moleculesof the substrate primer. The microme-chanical bond to dentin is formed by thepenetration of the resin into the tubules,creating tags and a resin-dentin inter-dif-fusing area called the "hybrid layer" (seeFig 6-12). 24 The features of a hybrid layer,formed by the penetration of liquid resininto the limiting layer of the etched dentin,

73


Fig 6-1 Occlusal wear in a com-posite restoration in a posteriortooth.

Fig 6-2 Evidence of microleak-age between composite anddentin (original magnification X1,000).

Fig 6-3 A dentinal tubule con-taining bacteria (original magnifi-cation X 13,000).

74

Advances in Composite Restorations

Fig 6-4 Simultaneous etching ofenamel and dentin.

Fig 6-5 Details of the etching ofenamel.

Fig 6-6 Fractured dentinal sur-face. Note the smear plugs in thedentinal tubules (original magnifi-cation x 2,000).

75


76

Fig 6-7 The dentin in the upperpart of the illustration was etchedwith 37% phosphoric acid for15 seconds. Note the removal ofthe smear layer (original magnifi-cation X 1,000).

Fig 6-8 Detail of Fig 6-7 (originalmagnification X 2,000).

Fig 6-9 Etched dentin fracturedl ongitudinally in the direction ofthe dentinal tubules. The expo-sure of collagen fibers is evident

( original magnification X 2,000).

Advances in Composite Restorations

Fig 6-10 Fractured dentin. Notethe removal of the peritubulardentin and the exposure of the

collagen fibers of the intertubulardentin (original magnification x5,000).

Fig 6-11

Details of the collagenfiber network (original magnifica-tion X 20,000).

Fig 6-12 A replica of a resin-com-posite interface (original magnifi-cation X 2,000) (T, resin tags; H,hybrid layer; D, dentin; R, resin).

77


Fig 6-13 Composite resin tags( original magnification x 500).

Fig 6-14 Fractured dentinal sur-face. Note the resin penetrationi nto the dentinal tubules (originalmagnification x 2,000).

Fig 6-16 Composite-dentin inter-face (original magnification x2,000).

78

Placement of Composite Restorations

depend on the relationship between thedepth of action of the etching acid and thecapacity of the resin to penetrate the con-ditioned dentin. 26 An excellent tooth-restoration interface is created by thematching action of these two mecha-nisms.30 Resin tags significantly increasethe bonding area (see Figs 6-13 and 6-14),and the hybrid layer may provide an "elas-tic" layer between the restorative materialand the underlying dental tissues (Fig 6-15) . 15,17,25,29

Placement of CompositeRestorations

With the use of appropriate adhesive sys-tems, it is possible to place compositerestorations without marginal gap forma-tion. 12 Such developments have realizednew horizons in conservative dentistry, 11with clinical and laboratory research beingdirected towards the use of new forms ofadhesive biomaterials for the provision ofesthetic restorations in posterior teeth. 16

Numerous studies have demonstratedthat composite resins are nontoxic and,when applied near the pulp, do not causean adverse reaction 6,11,17 ; most reactionsunder composite restorations are relatedto the presence of bacteria. The dentalpulp is not adversely affected by the etch-i ng of dentin prior to the placement of arestoration (Figs 6-16 and 6-17). 15

The use of a dental adhesive allows thepreservation of remaining tooth tissuesbecause it limits the need for retentivefeatures within a preparation. 5 It remainsi mportant, however, to remove all frankcarious dentin (Fig 6-18). This may be fa-cilitated by the use of caries detectors(Figs 6-19 to 6-22). 13

To optimize the bond between resin anddentin, it is important to use proprietaryetchants of sufficient strength. The use oflow-concentration etchants that are in-compatible with the adhesive system maynot eliminate the peritubular dentin and re-sult in resin tags, which are not adherent tothe dentin.

After etching, the cavity must be thor-oughlywashed. Following washing, it is im-portant to avoid excessive drying of thedentinal surfaces. Such drying results inthe collapse of the collagen network ex-posed by etching and may give rise tonanoleakage between resin and dentin inclinical service. 21 Appropriate drying of thedentin is achieved using Kanca's so-called"gentle dry" for 3 seconds. 22

For the placement of composite materi-al in a Class II preparation, it is consideredbest to use a metal matrix and plasticwedges to facilitate the restoration of theproximal anatomy and contact area. Sub-ject to confirmation of the findings of therecent study by Versluis et a1 32 which indi-cate that the direction of the application ofthe curing light does not influence the di-rection of polymerisation shrinkage, it mayprove possible to dispose with plastic ma-trices, reflecting wedges, and the require-ments to have multidirectional applica-tions of the curing light.27,28

According to the work of Davidson etal, 8 an increment of composite should notexceed 2 mm in depth. In another impor-tant study, Versluis et al explain that thedegree of polymerization tends to be uni-form following appropriate illuminationand that the thickness of an incrementdepends on the intensity of the activatingunit. 31 A recent study by Goracci et al indi-cates that the depth of cure that can beachieved with a light output intensity of

79


Fig 6-16 Histological section ofan extracted tooth 30 days aftercavity preparation, etching ofthe preparation with phosphoricacid (15 seconds), and restorationusing Bisco One Step Adhesive.No pulpal inflammation is appar-ent. Reparative dentin is presentsubjacent to the dentinal tubulescut during cavity preparation.

Fig 6-17 Details of the reparativedentin.

Fig 6-18 Demineralized cariousdentin (original magnification X1,000).

80


Fig 6-19 Cavex caries detector. Fig 6-20 The caries detector discloses caries indentin and increases the likelihood of conservativecavity preparation.

Fig 6-21 Detail of caries in dentin identified withcaries detector.

Fig 6-22 Detail of the preparation following cariesremoval.

500/600 mW/cm 2 is 4 mm (unpublisheddata).

Regarding the nature of the polymeriza-tion process, curing light intensity mayi nfluence the marginal integrity and seal ofcomposite resin restorations. 19 The useof a light-curing technique involving a grad-ually increasing exposure to the polymer-izing light has advantages in terms of en-hancing the adaptation of the compositeto the preparation (Fig 6-23). 7,8 Such find-ings may be confirmed by scanning elec-tron microscopic examinations of replicas

of tooth-restoration interfaces (Figs 6-24and 6-25).

On the basis of these findings, new light-curing units have been produced to allowthe polymerization of restorations of com-posite resins with light of increasing inten-sity. 9,10,25 The use of these lights helps tominimize stresses associated with poly-merization.

The restoration of a permanentmandibular first molar using the tech-niques described for preparation, etching,wet bonding, and polymerization is illus-

81

Direct Posterior Restorations-Technigbes for Effective Placement

Fig 6-23 Modified lamp with provision to regulate thei ntensity of the light emitted.

Fig 6-24 A replica of a restorationpolymerized using a conventionaltechnique (400 mW/cm 2 for 40seconds). The polymerizationcontraction has produced a 10-um microgap between dentin andresin (original magnification x

2,500) (T, resin tags; H, hybrid lay-er; G, microgap; D, dentin; R,resin).

Fig 6-25 A replica of a restorationpolymerized with progressive in-crease of light intensity (0-400mW/cm 2 for 30 seconds, then400 mW/cm 2 for 20 seconds).The resin composite is perfectlyadapted to the dentinal surface(original magnification x 2,000).

82


Fig 6-26 Caries in a permanent mandibular firstmolar.

Fig 6-27 Isolation with rubber dam.

Fig 6-28 Reproduction of occlusal morphology us-i ng an occlusal index of transparent silicone im-pression material.

Fig 6-29 Occlusal index removed.

trated in Figs 6-26 to 6-35. The anatomicform of such a composite resin restorationmay be readily reproduced using an oc-clusal index formed prior to cavity prepa-ration (Figs 6-28 and 6-29) and reposi-tioned on the tooth after placement of thecomposite material (Fig 6-33). The effec-tiveness of this technique is illustrated inFigs 6-34 and 6-35. Any cusp or marginalridge lost or damaged must be recon-structed in wax prior to forming the index.

Thetechnique is efficient and effective andmay contribute to improving the qualityand the subsequent clinical performanceof posterior composite restorations.

The use of composites in posteriorteethcontinues to be a challenge to many clini-cians. Ease and the speed of placement ofposterior composite and the subsequentin-service performance of such restora-tions may be enhanced with the applica-tion of the techniques described.

83


Fig 6-30 Application of etchant to the completed

Fig 6-31 Etching for 15 seconds.preparation.

Fig 6-32 Excess water removed with a brief blast

Fig 6-33 Polymerization of the final increment ofof air, leaving the dentin slightly moist.

composite through the transparent matrix.

Fig 6-34 Restoration after matrix removal.

Fig 6-35

Finished restoration. The anatomy ofthe occlusal surface has been reproduced.

84

References

References

1. Bergvall O, Brannstrom M. Measurements of thespace between composite resin fillings and thecavity walls. Sven Tandlak Tidskr 1971;64:217-226.

2. Brannstrom M. Communication between theoral cavity and the dental pulp associated withrestorative treatment. Oper Dent 1984;9:57-68.

3. Brannstrom M. Dentin and Pulp in RestorativeDentistry. London: Wolfe Medical, 1982.

4. Brannstrom M, Nordenvall KJ. Bacterial pene-tration, pulpal reaction and the inner surface ofconcise enamel bond. Composite fillings inetched and unetched cavities. J Dent Res 1978;57:3-10.

5. Buonocore MG. A simple method of increasingthe adhesion of acrylic filling materials to enam-el surfaces. J Dent Res 1955;34:849-853.

6. Cox CF. Biocompatibility of dental materials inthe absence of bacterial infection. Oper Dent1 987;12:146-152.

7. Davidson CL, De Gee AJ. Relaxation of poly-merization contraction stresses by flow in denti-nal composite. J Dent Res 1984;63:146-148.

8. Davidson CL, De Gee AJ, Feilzer A. The com-petition between the composite-dentin bondstrength and polymerization contraction stress.J Dent Res 1984;63:1396-1399.

9. de Gee A, Davidson CL, Smith AA. Modifieddilatometer of continuous recording of volumet-ric polymerization shrinkage of compositerestorative materials. J Dent 1981;9:36-42.

10. FellzerAJ, Dooren LH, De Gee AJ, Davidson CL.I nfluence of light intensity on polymerizationshrinkage and integrity of restoration-cavity in-terface. Eur J Oral Sci 1995;103:322-326.

11. Fusayama T. New Concepts in OperativeDentistry. Chicago: Quintessence, 1980.

12. Fusayama T. Optimal cavity wall treatment foradhesive restorations. J Esthet Dent 1990;2:95-99.

1 3. Fusayama T. A simple pain-free adhesiverestorative system by minimal reduction and to-tal etching. Tokyo: Ishiyako EuroAmerica, 1993.

14. Fusayama T. A study on marginal closureof composite resin-dentin margins. Jpn J ConDent 1986;29:177-186.

15. Fusayama T. Total etch technique and cavityi solation. J Esthet Dent 1992;4:105-109.

16. Glantz PO. On wettability and adhesion: A studyof enamel, dentin, some restorative dentalmaterials and dental plaque. Odontol Revy1 969;29(suppl 17):36-42.

1 7. Goracci G, Bazzucchi M, Mori G, Casa de'Martinis L. In vivo and in vitro analysis of a bond-i ng agent. Quintessence Int 1994;25:627-635.

18. Goracci G, Mori G, Bazzucchi M. Marginal sealand biocompatibility of a fourth-generationbonding agent. Dent Mater 1995;11:343-347.

1 9. Goracci G, Mori G, Casa de' Martinis L. Curingl i ght intensity and marginal leakage of resincomposite restorations. Quintessence Int 1996;27:355-362.

20. Goracci, Mori G, Casa de' Martinis L, BazzucchiM. Otturazioni in composito ed adesione allestrutture dentarie. Milano: Masson, 1994.

21. Gwinnett AJ. Structural changes in enamel anddentin of fractured anterior teeth after condi-tioning in vitro. J Am Dent Assoc 1973;86:117-122.

22. Kanca J. A method for bonding to tooth struc-

ture using phosphoric acid as a dentin-enamelconditioner. Quintessence I nt 1 991;22:

285-290.

23. Liebenberg WH. Occlusal index-assisted resti-tution of esthetic and functional anatomy in di-rect tooth-colored restorations. QuintessenceI nt 1996; 27:81-88.

24. Nakabayashi N. The hybrid layer: A resin-dentincomposite. Proc Finn Dent Soc 1992;88(suppl1):321-329.

25.Odian G. Principles of Polymerization, ed 3.New York: John Wiley and Son, 1991:227.

26. Pashley DH, Michelich V, Kehl T. Dentin perme-ability: Effects of smear layer removal. J ProsthetDent 1981;66:531-537.

27. Reinhart KJ. Der Einfluss der Lichtquelle auf dieRandbestandingkeit von Kompositfullungen.Dtsch Zahnarztl Z 1991;46:130-134.

85


28. Rueggeberg

F,

Caughman

W,

Curtis

JW.

31. Versluis A, Douglas W, Cross M, Sakaguchi RL.Factors affecting cure at depths within light-ac-

Does an incremental filling technique reducetivated

resin

composites.,' Am

J.

Dent

polymerization shrinkage stresses? J Dent Res1993;6:91-95.

1996;75:871-878.

29. Van Meerbeek B, Dhem A, Goret-Nicaise M,

32. Versluis A, Tantbirojn, Douglas WH. Do dentalBraem

M,

Lambrects

P, Vanherle G.

composite always shrink toward the light? JComparative SEM and TEM examination of the

Dent Res 1998;77:1435-1445.ultrastructure of the resin-dentin interdiffusionzone. J Dent Res 1993;72:495-501.

30. Van Meerbeek B, Inokoshi S,

Braem M,Lambrechts P, Vanherle G. Morphological as-pects of the resin-dentin interdiffusion zone withdifferent dentin adhesive systems. J Dent Res1992;71: 1530-1540.

86

Chapter 7

The "Composite-up" Technique: A SimpleApproach to Direct Posterior Restorations

Gilles F. Koubi, Stefan Koubi, and Jean-Louis Brouillet

Introduction

The purpose of this chapter is to report anovel technique for the placement ofesthetic composite resin restorations inposterior teeth. The advantages of directcomposite restorations in posterior teethinclude the preservation of remaining,sound tooth tissues. The indications fordirect composites in posterior teeth in-clude Class I and II restorations in premo-lars and Class I and small to moderateClass II restorations in permanent molarteeth. All posterior composite restorationsshould be placed under rubber dam, withthe provision of such restorations involvingfour phases of treatment:

1. Cavity preparation and hybridizationof the dentin to effectively protect thepulp-dentin complex.

2. Prewedging and the placement of athin sectional, precontoured metal ma-trix to facilitate the formation of proximalcontact points.

3. Placement of a chemically self-curedflowable composite in the base of thecavity to speed up the restorative pro-cedure and limit stresses associatedwith polymerization shrinkage.

4. Restoration of the occlusal portion us-i ng the "composite-up" technique. Thecomposite-up technique involves amulti-increment approach in whicheach increment is light cured for 3 sec-onds. With the occlusal portion placed,the surface of the restoration is finishedby applying and light curing (40 sec-onds) a thin layer of resin sealant to re-duce microcracks.

The reluctance of patients to acceptmetallic restorations increases day by day,with a growing diffidence toward the con-tinuing use of amalgam, which is suspect-ed by some of being toxic. Fortunately,such developments are matched by re-finement in the field of composite resinsand adhesive bonding systems, providingsubstitutes for traditional restorative mate-rials. Although modern composite resinsystems are reliable, many general dentalpractitioners remain uncertain astothe ap-plications and clinical procedures for thesuccessful use of such materials in poste-riorteeth. This chapter describes a clinicalprotocol for the routine use of compositeand related systems in the placement ofClass II restorations.

8 7

The "Composite-up" Technique: A Simple Approach to Direct Posterior Restorations

Fig 7-1 Occlusoproximal cavity in a maxillary firstpermanent molar.

been abandoned, given the efficacy of ad-hesive bonding systems that can ensurethe bonding and sealing of composite ma-terials to enamel-dentin substrates.11

The Operative Procedure

Following the successful completion ofcavity preparation, preceded by cleaningof the tooth with a slurry of pumice andwater and the application of rubber dam,the operative procedure may be consid-ered to comprise four stages:

I ndications

The indications for the use of compositesin posterior teeth are limited to Class Irestorations, Class II restorations in pre-molars and small- to moderate-sizedClass II restorations in permanent molars.When restoring large complex Class IIpreparations, an indirect approach shouldbe adopted. While composites can beplaced on a deeply located cervical mar-gin, assuming the margin is accessible, iti s preferable to limitthe application of com-posites to margins of enamel.

Cavity Preparation

Cavity preparation should be linked to theremoval of caries and finishing of the cavo-surface margins. The preparations shouldbe free of bevels with the cavosurfacemargins having a well-finished 90-degreeconfiguration (Fig 7-1). The traditionalprinciples of extension for prevention andcreation of retention form, which werevery costly of sound tooth tissues, have

1. Adhesion and biocompatibility mea-sures

2. Reconstruction of the proximal sur-face(s) according to anatomic andphysiologic requirements, including anappropriately located and formed con-tact point

3. Filling of the apical two thirds of thepreparation

4. Restoration of the occlusal surface toensure esthetics and function

Adhesion and BiocompatibilityMeasuresModern adhesive materials make it possi-ble to bond to and seal dentin 12,15 and tocreate a hybrid layer, 22,23 which protectsthe pulp from bacterial, chemical, andphysical insults that may give rise to pulpi-tis5,20 and postoperative pain. 7

Adhesive procedures involving the re-moval of the smear layer 4,17 are to be pre-ferred given their superior performanceand protection of the pulp. Such proce-dures involve (for a material such as AllBond II [Bisco Inc]): total etching (15 sec-onds) , 24 thorough rinsing (20 seconds), a

88


Fig 7-2 Following the application of the adhesive,the placement of a metal matrix and wedges facili-tates the restoration of the contact point.

Fig 7-3 Injection of self-curing, flowable compositeto fill the apical two thirds of the preparation.

15-second application of a biocompatibleprimer to moist dentin (wet bonding),10,13and application of the adhesive and sub-sequent light curing (30 seconds).

Reconstruction of the ProximalSurfacesGiven their flexibility, transparent polyestermatrices are difficult to position and controlin the reconstruction of proximal surfaces.Metal matrix, which can be contoured, ifnot precontoured, can be accurately ap-plied and adapted to cervical margins withwedges. Plastic wedges, given their greaterhardness, should be preferred over wood-en wedges. The wedges, if appropriatelyapplied, also cause separation of the teethand facilitate the for-mation of an appropri-ate contact point (Fig 7-2).

Filling of the Apical Two Thirdsof the PreparationComposites shrink on polymerization,which is a principal limitation of such ma-terials. Polymerization shrinkage gives riseto microleakage and the possibility of post-operative sensitivity and secondary caries.

The polymerization shrinkage of com-posite resins is mass-dependent, necessi-tating an incremental approach to theplacement of light-cured composites. 25

The time and attention required to place aClass II composite restoration may be lim-i ted by a single application of a chemicallyself-curing composite resin in the base ofthe preparation, according to the tech-nique of Bertolotti. 2 Using a flowable com-posite (eg, Bisfil 213, Bisco Inc) witha paste-paste presentation, the singleapplication of self-curing composite maybe made using an injection technique, fill-ing the preparation to the level of the oc-clusal dentinoenamel junction 21 ( Fig 7-3).Polymerization of the self-curing compos-ite occurs within 2 minutes, leaving an oxy-gen-inhibited layer on the surface of thematerial. This layer contributes to the bond

89


Fig 7-6 The viscous nature of the light-cured com-posite facilitates the creation of occlusal form.

Fig 7-8

Application of the second increment of

Fig 7-9 The development of the occlusal anatomy.li ght-curing composite.

90

Fig 7-7 Spot light curing (>100mW/cm 2 ) of the ini-tial increment (3 seconds).


Fig 7-10 The occlusal grooves and pits are high-

Fig 7-11

Application of a thin layer of sealant toli ghted with tints.

finish the surface of the restoration.

Fig 7-12 Light curing (> 400mW/cm 2 ) of the new-ly placed restoration (40 seconds).

Fig 7-13 Following removal of the matrix, "fine fin-i shing" may be required.

Fig 7-14 Finishing of the restoration.

Fig 7-15 The completed restoration.

91


between the self-curing material and sub-sequent increments of light-cured materialapplied to restore the occlusal portion ofthe restoration. Although self-curing com-posites suffer polymerization shrinkage,this shrinkage is less than that which oc-curs with light-cured composites 4,15 whichmay shrink to the extent that cervicaldebonding occurs. The activation of self-curing composites occurs relatively slowly,commencing where the material comesinto contact with the relatively warm wallsof the preparation. Shrinkage in associa-tion with these walls is, as a result, partial-ly eliminated . 8 I n addition, according toGarberoglio 9 and Alsten,1 the numerousair inclusions in self-curing composites actas "absorbers" of shrinkage stresses, giv-i ng further advantages to self-curing mate-rials.

Restoration of the OcclusalSurfaceOnce the appropriate shades and colormodifiers (Fig 7-4) for the light-curing com-posite have been selected, the occlusalsection is restored incrementally. The vis-cous nature of light-cured compositeshelps give the necessary rounded form tocuspal features (Figs 7-5 and 7-6). Aftereach application of a small increment ofmaterial, using, for example, a Hollenbackcarver, the composite is contoured andspot cured for 3 seconds, using a light withan intensity greater than 100mW/cm 2 , ac-cording to the "pulse delay technique" (Fig7-7) as advocated for a material such asVIP (Bisco Inc). 1 8,19 I ncremental buildup( Fig 7-8) gives control of cuspal form andallows the creation of pits and fissures (Fig7-9), while facilitating good color match( Fig 7-10) To strengthen the surface of the

restoration and to reduce microcracks andother microscopic defects, a thin layer of asealant (eg, Fortify, Bisco Inc) is applied( Fig 7-11) and the restoration is then lightcured for 40 seconds with a light intensitygreater than 400mW/cm2 ( Fig 7-12).

The composite-up technique is consid-ered to reduce residual stresses in therestoration, in particularatthe margins andalong the walls of the preparation. The"C factor," as described by Feilzer et al , 6 isminimized (0.5 versus 5 for conventionaltechniques), limiting the formation ofcracks in adjacent enamel. In addition, thecontrolled "soft polymerization" of thecomposite is considered to be advanta-geous.' 6

FinishingFinishing of the restoration is accom-plished by removal of the wedges, matrix,and rubber dam and completion of anynecessary occlusal refinements, cleaning,and polishing (Figs 7-13 to 7-15).

Conclusions

The composite-up technique provides aneffective state-of-the-art approach to theplacement of Class II composite restora-tions, with consistent biologic, esthetic,and functional qualities.

92

References

References

1. Alsten D, FeilzerAJ, De Gee AJ, Mol A, DavidsonCL. The dependence of shrinkage stress re-duction on porosity concentration in thin layers.J Dent Res 1992;71:1619-1622.

2. Bertolotti RL. Posterior composite techniqueutilizing directed polymerization shrinkage anda novel matrix. Pract Periodontics Aesthet Dent1 991;3(4):53-58.

3. Cox CF, Keall C, Keall H, Ostro E, Ber-genholtz G. Biocompatibility of surface-sealeddental materials against exposed pulps. JProsthet Dent, 1987;57:1-8.

4. Davidson CL. Resisting the curing contractionwith adhesive composites. J Prosthet Dent1986;55:446-447.

5. EickJD, Robinson SJ, ByerleyTJ, Chappell RP,Spencer P, Chappelow CC. Scanning transmis-sion electron microscopy/energy-dispersivespectroscopy analysis of the dentin adhesive in-terface using a labeled 2-hydroxyethyl-methacrylate analogue. J Dent Res 1995;74:1 246-1252.

6. Feilzer AJ, De Gee AI, Davidson CL. Settingstress in composite resin in relation to configu-ration of the restoration. J Dent Res 1987;66:1636-1639.

7. Fusayama T. Factors and prevention of pulpi rritation by adhesive composite resin restora-tions. Quintessence Int 1987;18:633-641.

8. Fusayama T. Indications for self-cured and light-cured adhesive composite resin. J ProsthetDent 1992;67:46-51.

9. Garberoglio R, Coli P, Branstrom M. Contractiongaps in Class II restorations with self-cured andli ght-cured resin composites. Am J Dent 1995;6:303-307.

1 0. Gwin net AJ. Moist versus dry dentin: Its effect onshear bond strength. Am J Dent 1992;5:127-129.

11. Hosoda H, Fusayama T. A tooth substance sav-i ng restorative technique. Int Dent J 1984;34:1 -12.

1 2.Inokoshi S, Iwaku M, Fusayama T. Pulpalresponse to a new adhesive restorative resin.J Dent Res 1982;61:1014-1019.

13. Kanca J. Effect of resin primer solvents andsurface wetness on resin composite bondstrength to dentin. Am J Dent 1992;5:213-215.

14. Kanca J. Resin bonding to wet substrate. I.Bonding to dentin. Quintessence Int 1992;23:39-41.

15. Kemp-Sholte CM, Davidson CL. Marginal seal-i ng of curing contaction gaps in CI V compositeresins restorations. J Dent Res 1988;67:841-845.

1 6. Koran P, Kurschner R. Effect of sequentialversus continuous irradiation of a light-curedresin composite on shrinkage, viscosity, S ad-hesion, and degree of polymerization. Am J

Dent 1998;10:17-22.

17. Nakabayashi N, Kojima K, Masuhara E. The pro-motion of adhesion by the infiltration ofmonomers into tooth substrates. J BiomedMater Res 1982;16:265-273.

1 8. Suh BI. Understanding and Controlling theEffect of Polymerisation Shrinkage Stress inComposite Restoration [Proceedings of theThird International Symposium on Adhesionand Reconstruction in Modern Dentistry, 26-27Mar 1999, Santa Margherita Ligure, Italy]. Milan:Medico-scientific, 1999:60-67.

19. Suh BI, Cincione FA, SandrikJL. Examination ofexperimental cavity substrate as a function ofmodulus of elasticity during polymerization ofcomposite [abstract 1242]. J Dent Res 1998;77:261.

20. Suzuki S, Cox CF, White KC. Pulpal res-ponse after complete crown preparation, denti-nal sealing, and provisional restoration.Quintessence Int 1994;25:477-485.

21. Tassery H, Dejou J, Koubi G, Brouillet JL. Lesrestaurations posterieures directes, choix dusubstitut dentinaire. Inf Dent 1998;6:365-370.

22. Van Meerbeek B, Dhem A, Goret-Nicaise M,Braem M, Lambrechts P, Vanherle G.Comparative SEM and TEM examination ofthe ultrastructure of the resin-dentin interdiffu-sion zone. J Dent Res 1993;72:495-501.

93


23. Van Meerbeek B, Inokoshi S,

Braem

M,

25. Versluis A, Douglas WH, Cross M, SakaguchiLambrechts P, Vanherle G. Morphological as-

RL. Does an incremental filling technique re-pects of the interdiffusion zone observed with

duce the polymerization shrinkage stresses? Jdifferent dentin adhesive systems. J Dent Res

Dent Res 1996;75:871-878.1992;71:1530-1540.

24. Van Meerbeek B, Peumans M, Gladys S, BraemM, Lambrechts P, Vanherle G. Three-year clini-cal effectiveness of four total-etch dentinal ad-hesive systems in cervical lesions. QuintessenceInt 1996;27:775-784.

94

Chapter 8

Materials and Luting Cements forI ndirect Restorations

Marco Ferrari, Alessandro Vichi, and Albert J. Feilzer

I ntroduction

An important aim in restorative dentistryis to restore decayed and damaged teethi n such a way that the anatomy and func-tion is reestablished and exposed dentaltissues are protected against the infiltrationof harmful fluids. 2 A further aim is adurable restoration. To realize this aim, thedentist can generally choose between adirect or indirect restorative technique.Traditionally, indirect gold restorationshave been considered the most durablerestorations. Today, direct adhesive restora-tions are in many cases a viablealternative; however, they are not withouttheir shortcomings. When there is no ad-hesive bond between the restoration andthe dental hard tissues, marginal gap for-mation will result from polymerizationshrinkage. As a consequence, marginall eakage may occurwith the inherent risk ofsecondary caries and postoperative sensi-tivity. 22 When a bond between the restora-tive material and tooth tissues is present,severe shrinkage stresses may develop inthe restored tooth,9 which puts the adhe-sion of the restoration to the cavity walls atrisk. Postoperative sensitivity, cuspal flex-

ure, and crack formation in the enamelmay be the first signs and symptoms ofshrinkage stresses in the restored toothunit. By using indirect techniques, many ofthese shortcomings may be avoided.Moreover, new dental materials and tech-niques have recently been introduced tofacilitate the provision of indirect estheticrestorations with appropriate strength, bio-compatibility, resistance to wear, and fit.Esthetic concerns have led to the intro-duction of a number of all-ceramic sys-tems (eg, Dicor, Dentsply, York, PA; Vita Hi-Ceram, Vident, Baldwin Park, CA; Optec,Jeneric, Wallingford, CT; IPS Empress andEmpress, 9 I voclar, Schaan, Liechtenstein).

The aim of this paper is to provide anoverview of esthetic materials for indirectrestorative techniques.

Esthetic Materials for IndirectTechniques

Ceramics, Glasses, andPorcelainsPorcelain is an esthetic material that hasbeen used as a dental restorative materialfor more than 150 years. Historically, the

95

Materials and Luting Cements for Indirect Restorations

use of porcelain as a restorative materialwas limited because of its brittleness andlack of elasticity. The development of newproduction techniques and adhesive ce-ments have, however, resulted in dentalporcelains enjoying a successful revival.

A ceramic is a material that consists of acompound of a metal with a nonmetal,often an oxide, that exists in a crystallinephase in an amorphous glass matrix. Aporcelain is an opaque, nonfusing combi-nation of silica and potash, while glass isa translucent, fusing combination of silicaand potash. A glass can have the samecomposition as a ceramic, but it lacks thecrystalline phase. Glasses can be cast us-i ng a method that is similar to that used formetal alloys. After casting, restorations ofglasses undergo a "ceramming" proce-dure in an oven during which a crystallinephase develops. The manufacturers addsome impurities to the glasses to facilitatethe cerammingprocess.

Currently dentists can choose one ofseveral materials for the production of ani ndirect ceramic restoration. To ensure astrong and durable porcelain restoration, itis necessary to make provision for a mini-mum restoration thickness of 1.0 to 1.5mm. Prior to the availability of adhesive ce-ments, the strength of the crown depend-ed solely on the material itself. With the useof adhesive cements, a strong adhesivebond can be formed between tooth tis-sues and the ceramic restoration, strength-ening and supporting the restoration,while also limiting the need to sacrificesound tooth tissue at the time of prepara-tion. New developments in ceramics arebased on different construction tech-niques and on stronger base materials (eg,I n-Ceram and Procera or Zirconiumoxide).

Resin CompositesGreat efforts have been made to improvethe mechanical properties of direct tooth-colored restoratives. As a result, the me-chanical qualities of composite resins havereached a level comparable to that of amal-gam. Large restorations of compositeresins are not, however, easy to place andcontour. Furthermore, the lack of dimen-sional stability of these materials duringcuring can require an increased use of in-direct techniques employing one of a num-ber of systems (eg, Targis Vectris, IvoclarAG). An interesting new approach is theuse of fiber-containing systems.

Human Tooth Tissue:"The Natural Inlay"I n 1998, Moscovich and Creugers 18 i ntro-duced a method to use extracted teeth inthe provision of indirect restorations-the"natural inlay." The inlay is formed from awax pattern using a copy-milling device( Celay, Microna, Switzerland). Although iti s a very creative idea, it is questionable asto whether this technique has any future.This is the first form of dental restoration inwhich caries may develop.

Materials for CementingI ndirect Restorations

Adhesive CementsMany systems are now available for the ad-hesive cementing of ceramic and indirectcomposite resin restorations (Table 8-1). Achoice can be made from a spectrum ofmaterials, ranging from purely compositeresin cements combined with an adhesivebonding system to traditional glass-ionomer cements, which bond to tooth tis-

96

Materials for Cementing Indirect Restorations

Table 8-1 Adhesive cements: Classification and properties

sues without the need of adhesives. Resin-modified glass-ionomer cements andcompomer cements may be of particulari nterest in the future because of their easeof use.

Resin luting cements are primarily indi-cated for the luting of porcelain restora-tions. The esthetic qualities and fracturestrength of restorations are markedly in-creased by adhesive luting. 15 Marginal ac-curacy and seal remain crucial factors inthe clinical performance of indirectrestorations. The type of finishing line usedcan affect the quality of the marginalseal. 13 Porcelain restorations require ashoulder- or chamfer-type tooth prepara-

tion with a rounded angle. 5,13,15,26 Reportsi n the literature confirm that it is possible toproduce restorations using routine labora-tory techniques with a degree of "loose" fit,which results in a cement film thickness ofapproximately 50 utm.1,11,13

Seating of restorations with a resin lutingcement has several advantages. The solu-bility of the exposed resin luting cement isnegligible in the oral environment, and afil m thickness of 20 to 30 um may be ob-tained.20

9 7


Table 8-2 Nonadhesive cements: Classification and properties

Nonadhesive CementsNonadhesive cements (Table 8-2) for thecementing of ceramic and indirect com-posite resin restorations require prepara-tions to be retentive and the restorations tohave sufficient inherent strength. This ap-plies even for full crowns of very strong ce-ramics (eg, In-Ceram). It is, therefore, ques-tionable as to whether it is appropriate touse nonadhesive cements for such pur-poses.

Bonding to Dental Tissues

Three dental substrates are involved in thebonding of indirect esthetic restorations:enamel, dentin, and cementum (Fig 8-1).

Enamel predominates along the oc-clusal and axial margins of Class II cavitypreparations.23,24 At the occlusal margins,a very thick layer of enamel forms the sub-strate for a durable bond with adhesive lut-ing materials, while along the axial wallsthe enamel is much thinner (Fig 8-2).

98

I n any one cavity, the dentinal substrateshows different morphology according tothe area observed.4,12 Moving fromthe outer cavity margins toward the pulp,tubule density and size increase. Also, thedentinal substrate may comprise differenttypes of dentin, including sclerotic, young,deep, superficial, and carious dentin (seeFig 8-1). Although hybridization of marginsof dentin and cementum has been demon-strated 12 ( Fig 8-3), the absence of resintags in the limiting 200 to 300 um of thecervical margin indicates no peritubulardentin demineralization and therefore, al imited increase of intertubular surfacearea after conditioning (Fig 8-4). 4,12 Thismay be responsible for a relatively lowbond strength and, as a consequence, lowdurability of the bond to the cavity margin.I n fact, the cervical margin is the least reli-able section of a Class II preparation forsealing. The presence of an outer layer,partially formed by cementum 150 to 400um thick, may affect the quality of bondingwhen the margin is located below the ce-mentoenamel junction (CEJ)4,12 ( Fig 8-5).

Bonding to Dental Tissues

Fig 8-1 Different dental substrates present in the same cavity after etching (a, enamel margin; b, deep dentin;c, occlusal enamel; d, thin enamel cervical margin; e, sclerotic dentin; f, carious dentin; g, intertubular dentin).

Fig 8-2 Thick enamel is presentalong the occlusal margins of aClass 11 cavity. Along the axialwalls of a Class II cavity, only thinenamel is present (O, occlusalenamel; A, axial enamel) (originalmagnification X 10).

99


Fig 8-3 Hybridization of a cementodentinal margin in a vital tooth (original magnification x 7,500).

When the cervical margin is locatedabove the CEJ, the thickness of the enam-el is important. When the enamel margin is0.3 to 0.8 mm, it cannot provide the sub-strate for a perfect seal of the restoration( Fig 8-6).10,19 This may be caused by thefact that in thin cervical enamel the prismsrun predominantly parallel and, as a con-sequence, a relatively low bond strength isdeveloped. 10,19,23,24

The bonding mechanism to dental sub-strates is based on resin tags, with lateralbranching and hybrid layer formation. 20,21

Forthis to occurwith new adhesives, a pre-requisite is the correct acidic treatment ofthe substrate. More heavily mineralizedsubstrates, such as enamel and scleroticdentin, must be etched for longerthan lessdemineralized structures such as nonscle-rotic dentin and cementum.

Techniques for theConstruction of IndirectRestorations

Bench-Made RestorationsGiven the opportunities afforded by layer-ing techniques and the use of materialswith different translucencies and colors,bench-made indirect restorations are themost esthetic form of indirect restoration.The final quality of the restoration dependsto a large extent on the dental technician.For this reason, the quality of restorationsmade by this technique is not as pre-dictable as that of restorations made byother means.

1 00

Fig 8-5 View of a cervical margin placed below the CEJ. An outer dentinal layer is evident (D, dentin; OL, outer layer; C, cementum) (original magnifi-cation x 1,000).

Fig 8-4 Resin replica of a cervical margin placed below the CEJ. No resin tags are evident in the first 200 to 400 um from the cervical margin (arrows,C, cementum; OL, outer layer; T, resin tags) (original magnification x 500).


CastingThe casting technique is a generally avail-able and relatively inexpensive methodthat invariably gives a predictable fit to thefinal restoration. The material used for thecasting of ceramic restorations is typicallyaglassthat,when melted, has afluiditythatfacilitates complete casting. After castingi n glass, a restoration must be cerammed.This lengthy procedure results in the glassbecoming a composite that includes acrystalline phase. The strength of this typeof restoration tends to be insufficient instress-bearing locations.

Another approach to the casting of ce-ramic restorations is the pressing tech-nique (eg, the Empress product range).With this technique porcelains can beused instead of glass, which results instronger restorations that can be used instress-bearing regions. The esthetic quali-ty of such restorations is relatively poor giv-en that the restoration is one color, al-though surface stains may be added.

1 02

MillingCeramic materials are very strong. Whenusing ceramics in dentistry it is possible toprovide restorations with high intrinsicstrength. However, impurities and voids inceramics have a weakening effect. For thisreason, ceramic blanks manufactured un-der controlled conditions are strongerthanspecimens of ceramic produced by atech-nician at the bench. Through the milling ofpreformed ceramic blanks using aCAD/CAM system or copy milling device,it is therefore possible to produce restora-tions of high strength. However, suchrestorations suffer the disadvantage of be-i ng monochromatic. To overcome thisproblem, two-color blanks may be used

Application Technique

and the final restoration may be character-ized by external staining. The CiceroCAD/CAM system relies on the milling of ablock of porcelain that has been baked onan investment die.

Quality of Indirect Restorations

Until there have been further develop-ments in bonding14,17,20 with improve-ments in marginal seal and the clinical per-formance of esthetic restorations, 27,28

problems of adaptation and leakage willcontinue to occur at the gingival marginsof indirect restorations. 7,16 Robinson et a1 25and Dietschi et alb noted that the marginaladaptation of indirect restorations was bet-ter than that of direct restorations in ClassI I cavities. Dietschi et alb also pointed outthat when residual enamel is less than 1mm in height or 0.5 mm in thickness, indi-rect ratherthan direct restorations have su-perior marginal qualities. Less leakagemay be found with indirect Class II restora-tions (inlays) compared to direct estheticrestorations. This is probably because in-lays do not suffer polymerization shrink-age during placement, except forthe smallamount associated with the thin layer ofcomposite resin luting cement ,

8 and there-fore suffer limited variations in clinical pro-cedures. Leakage at the margins of ClassI I restorations is correlated with the type ofdental substrate forming at the margins,the etching procedures used, and the typeof bonding system selected . 3 However,Hilton et al 16 and Ferrari et al 12 have re-ported an extensive leakage along the fa-cial and lingual enamel walls of Class II di-rect and indirect esthetic restorations.


A case is demonstrated in Figs 8-7 to 8-18to further explain the application of the ad-hesive technique using luting restorations.Since adhesion is crucial to the success ofbonded ceramic restorations, great caremust be taken in the conditioning of thesurfaces. If the patient has had provisionalrestorations, it is important to remove allremnants of the provisional cement with-out damaging the surface. Surfaces maybe cleaned prior to etching/conditioningby sandblasting. The ceramic surfaceshould be conditioned (etched with hy-drofluoric acid and silanated) in the dentaloffice immediately prior to insertion of therestoration to guarantee an optimal com-posite-ceramic bond.

103


Fig 8-7 Maxillary first premolar with a large defect.

Fig 8-8 To completely remove the caries, the caviEsthetic considerations and shape of the lesion in-

ty is stained with a caries detector.dicate an indirect porcelain restoration.

Fig 8-9 Try-in of the porcelain inlay.

Fig 8-10 A microsandblaster is used to clean thepreparation.

Fig 8-11 Phosphoric acid is applied to the enamel

Fig 8-12

Phosphoric acid is applied to themargins for 15 seconds.

entire preparation for 15 seconds.

1 04


Fig 8-13 The cavity is rinsed and gently air dried.

Fig 8-14 A primer adhesive solution is applied andthen light cured for 20 seconds.

Fig 8-15 The etched and silanated inlay is ready to

Fig 8-16

During the initial setting of the resinbe luted into the cavity.

cement, excess cement is removed with a probe.

Fig 8-17

Excess resin is removed from the inter-

Fig 8-18 Occlusal view of the completed restora-proximal area with floss.

tion.

1 05


References

1. Anderlini G, Calandriello R. Composite resinsand enamel-dentin adhesives. A new fixationtechnique [in Italian]. Dent Cadmos 1990;58(5):28-39.

2. Brannstrom M, Vojinovi O. Response of the den-tal pulp to invasion of bacteria around three fill-i ng materials. J Dent Child 1976;43:15-21.

3. Cagidiaco MC. Bonding to Dentin: Mechanism,Morphology and Efficacy of Bonding ResinComposites to Dentin In Vitro and In Vivo [the-sis]. Amsterdam: University of Amsterdam,1995.

4. Cagidiaco VIC, Ferrari M, Vichi A, Davidson CL.Mapping of tubule and intertubule surface areasavailable for bonding in class V and class IIpreparations. J Dent 1997;25:379-389.

5. Campbell SD. Esthetic modification of cast den-tal ceramic restorations. Int J Prosthodont1 990;3:123-129.

6. Dietschi D, Scampa G, Campanile U, Holtz J.

Marginal adaptation and seal of direct and indi-rect Class II composite restorations: An in vitroevaluation. Quintessence Int 1995;26:127-138.

7. Donly KJ, Jensen ME. Posterior compositeClass II restorations: In vitro comparison ofpreparation designs and restoration tech-niques. Dent Mater 1990;6(2):88-93.

8. Feilzer AJ, De Gee AJ, Davidson CL. Increasedwall-to-wall curing contraction in thin bondedresin inlays. J Dent Res 1989;68:48-50.

9. Feilzer AJ, De Gee AJ, Davidson CL. Settingstress in composite resin in relation to configu-ration of the restoration. J Dent Res1987;66:1636-1639.

10. Fernades CP, Chevitarese O. The orientationand direction of rods in dental enamel. JProsthet Dent 1991;65:793-800.

11. Ferrari M. Cement thickness and microleakageunder Dicor crowns: an in vivo investigation. IntJ Prosthodont 1991;4:126-131.

12. Ferrari M, Cagidiaco MC, Davidson CL.Resistance of cementum in Class II and V cavi-ties to penetration by an adhesive system. DentMater 1997;13(3):157-162.

13. Friedlander LID. The effect of tooth preparationdesign on the breaking strength of Dicorcrowns: Part I. Int J Prosthodont 1990;3:59-168.

14. Gwinnett AJ, Kanca J. Micromorphological rela-tionship between resin and dentin in vivo and invitro. Am J Dent 1992;5:19-23.

1 5. Haller B, Klaiber B, Hofmann N. Bonded all-ceramic restorations with the IPS Empresssystem. Pract Periodontics Aesthet Dent1993;7:39-49.

16. Hilton TJ, Schwartz RS, Ferracane JL. Mi-croleakage of four Class II resin composite in-sertion techniques at intraoral temperature.Quintessence Int 1997;28:135-144.

1 7. Kanca J. Resin bonding to wet substrate. I.Bonding to dentin. Quintessence Int 1992;23:39-41.

18. Moscovich H, Creugers NH. The novel use ofextracted teeth as a dental restorative material-the "Natural Inlay." J Dent 1998;26:21-24.

19. Munechicka T, Suzuki K, Nishiyama M. A com-parison of the tensile bond strengths of com-posite resins to longitudinal and transverse sec-tions of enamel prisms in human teeth. J DentRes 1984;63:1079-1082.

20. Nakabayashi N, Nakamura M, Yasuda N. Hybridl ayer as dentin-bonding mechanism. J EsthetDent 1991;3(4):133-138.

21. Nakabayashi N, Pashley DH. Hybridization ofdental hard tissue. Berlin: Quintessence, 1998.

22. Pashley DH, Dejew DD, Gallowey SE. Micro-l eakage channels: Scanning electron micro-scope observation. Oper Dent 1988;14:68-73.

23. Radlanski RJ. Prism arrangement in the earlyl ayers of human fetal enamel. In: Ralanski RJ,Renz H. Proceedings of the 10th InternationalSymposium on Dental Morphology. Berlin: C&MBrunne, 1995.

24. Radlanski RJ, Seidl W, Steding G, Jager A. Theorientation of prisms in the dental enamel of hu-man permanent teeth [in German]. Anat Anz1990;170:329-337.

25. Robinson PB, Moore BK, Swartz ML. Com-parison of microleakage in direct and indirectcomposite restorations in vitro. Oper Dent1987;12:113-116.

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26. Shillinburg

HT,

Jacobi

R,

Brackett

SE.

28. Van Meerbeek B, Peumans M, Verschueren M,Fundamentals of Tooth Preparation for Cast

Lambrechts P, Vanherle G. Clinical status of tenMetal and Porcelain Restorations. Chicago:

dentin adhesive systems. J Dent Res 1994;73:Quintessence, 1987.

1690-1702.

27. Tyas MJ. Clinical performance of two dentineadhesives: 2-year results. Aust Dent J 1996;41:324-327.

107

Chapter 9

I ndirect Restorations for Anterior TeethSpace-The Eternal Problem

Richard Ibbetson

I ntroduction

The range of esthetic restorations for ante-rior teeth has continued to broaden overthe last 25 years. The ability to bondporcelain to tooth structure has increasedthe options available to the modernrestorative dentist. Developments in ce-ramics have allowed increased use ofall-ceramic restorations in some areas ofthe mouth where perhaps they wouldpreviously have been contraindicated.However, longer term evaluation of someof these newer ceramic systems is stillneeded.

Successful results with ceramic andmetal-ceramic restorations in the anteriorpart of the mouth require that appropriatespace is made available for the technicianto create an effective esthetic illusion. Morespace is required for ceramic restorationsof thickness sufficient to realize optimalphysical properties. This requires con-trolled tooth reduction, and the responsi-bility for this rests with the dentist. If re-duction is excessive, pulpal damage mayresult. Precise tooth preparation is neces-sary to create resistance and retentionform for traditional cemented restorationsand to facilitate the use of resin luting ma-terials in modern, adhesively bonded

restorations. If tooth preparation fails tocreate sufficient space for an adequatethickness of restorative material, the resultcould be a thin restoration that is prone tofracture. However, more often such inade-quacies result in restorations that havepoor contour and poor esthetic results.

Unfortunately, dentists frequently makeerrors in tooth preparation. These are notsolely the province of dentists with lowerlevels of ability, but are common through-out the profession. Therefore, althoughsuch errors could be interpreted as a signof underperformance, they are more cor-rectly seen as evidence that accurate toothpreparation is difficult.

Common Errors in AnteriorTooth Preparation

The position of the facial margin in ananterior indirect preparation is critical bothto the final esthetic result and also to thehealth of the gingival tissues. It is well-known that if subgingival margin place-ment is necessary for esthetic purposes,the preparation should intrude minimallyi nto the gingival crevice. However, dentistsfrequently fail to control the relationship oftheir preparation to the crevice, particularly

109

I ndirect Restorations for Anterior Teeth

failing to appreciate how far coronally theinterdental papilla may lie on an anteriortooth (Fig 9-1). Consequently, errors inmargin placement are often associatedwith gingival inflammation (Fig 9-2).

A further error in margin placementoccurs in the area of the proximolabial lineangles. Anatomically, the tooth "waists in"quite markedly in these areas. When cut-ting a full crown preparation and tryingto establish a labial shoulder or heavychamfer facially, the dentist commonlyestablishes the finish line slightly coronalto the required position and then gradual-ly moves it further apically. In the area ofthe proximolabial line angles, such a tech-nique frequently results in loss of the widthof the finishing line as the tooth suddenlybecomes narrower as the tip of the burmoves apical ly. Attempts to reestablish thefull width of the finish line frequently placesthe margin significantly below the gingivalmargin.

Both of the above errors could beavoided if dentists better understood theanatomy and form of teeth.

Taper of Preparations

this is not true. A preparation with a taperof less than 10 degrees will, when viewedby this method, appear to be undercut.Better methods exist for assessing taper inpreparations. Many of these are based onthe use of the bur in the handpiece as asurveying rod to assess alignment and rel-ative parallelism of the axial walls. Thisserves to illustrate the fallibility of the hu-man eye in assessing geometric form, afactor of significant importance if we are toproduce preparations of high quality.

Most dentists are familiar with the factthat the facial aspects of teeth are curved.The extent of the curvature is dependenton the length of the clinical crown of thetooth. How is it then that we see prepara-tions such as that illustrated in Fig 9-3?This is the die of a preparation of a maxil-l ary incisor. The facial aspect of the prepa-ration is in one plane. There has been noattempt to recreate the natural curvature ofthe facial aspect of this tooth. How doesthis come about? It is not necessarily thesign of a careless dentist; rather, it indi-cates that tooth preparation is difficult andthat assessment of preparations is not bestcarried out using the naked eye alone.

Dentists have always been taught to try toproduce low values for the taper of theaxial walls of crown preparations. In tradi-tional cemented crowns, low values oftaper are important in minimizing thestress applied to the cement lute duringfunction. Most dentists have been trainedto assess taper by viewing the preparationaxially in a mirror with one eye from a dis-tance of 30 to 40 cm. 7 They have been toldthat if they had produced less than 10 de-grees of taper, the opposing walls of thepreparation would be just visible; however,

Methods of Assessing ToothReduction

Many techniques have been suggestedfor aiding the dentist in assessing toothreduction for indirect anterior restorations.Great emphasis has always been placedon the benefits of having the experiencedeye of the mature practitioner. Illustrationssuch as those discussed earlier indicatethe fallibility of the human eye in assessingthe quantity and quality of tooth reduction.Some way of monitoring or measuring

110

Methods of Assessing Tooth Reduction

Fig 9-1 The interdental papillali es significantly coronal to thel abial margin.

Fig 9-2 Anterior crown with the gingiva showing inflammation as aresult of the subgingival margin placement.

Fig 9-3 Die of an anterior crownpreparation showing only oneplane of facial reduction.

111


Fig 9-4 Depth cuts are used to aid tooth reduction.

tooth reduction would surely be beneficial.Following are a number of recommenda-tions.

Depth CutsMany dentists have been taught to usedepth cuts on the functional and axialsurfaces of teeth prepared for crowns (Fig9-4). How many know the diameter of theburs used to make the depth cuts?Without this knowledge, the depth cut haslittle value. Moreover, depth cuts often aremade slightly shallower than needed.Once the tooth surface between the depthcuts has been reduced, the depth cutsthemselves have lost their reference point.I f they are not prepared initially at an ade-quate depth, further reduction assessmentbecomes important.

MatricesOne useful way of assessing the amountof reduction is by the use of a matrix madeof the tooth before preparation, sectionedeither along the incisal edges of the anteri-

Fig 9-5 Sectioned matrix is used to assess tooth re-duction.

or teeth or buccolingually (Fig 9-5). This isan extra step in the clinical procedure andtherefore is often not easily adopted bypractitioners. However, its use should beencouraged because it provides a definiteindication of the amount of tooth prepara-tion that has been carried out and specificinformation about the location and amountof reduction. It should be adopted by den-tists, not necessarily for routine use, but asa way of checking their overall perfor-mance in tooth preparation from time toti me. These matrices, formed from siliconeputty, can be made directly on the tooth be-fore preparation begins or on a diagnosticwaxup or study cast.

Provisional CrownAn excellent way of assessing the adequa-cy of the tooth preparation is by makinguse of the provisional crown. If the provi-sional crown is made and adjusted forboth form and function, its thickness canbe measured to ensure that the toothpreparation is adequate and appropriate(Fig 9-6). If it is found that reduction is

11 2

The Management of Worn Teeth

Fig 9-6 Measuring the thickness of a provisionalcrown.

Fig 9-7 Worn anterior teeth.

i nadequate, modifications can be made. Itgoes without saying that the use of thistechnique requires that the provisionalrestoration is made before the working im-pression.

The use of techniques that measure theamount of space that has been created forthe restoration is likely to result in moreadequate crown preparations. This reflec-tive practice is also likely to develop thepreparation skills of the dentist.

The Management ofWorn Teeth

The reduction in dental disease and thecontinued developments in restorativematerials have resulted in the provision offewer full-coverage restorations. The ap-propriate use of adhesive restorative tech-niques provides significant opportunitiesfor avoiding full-coverage ceramic andmetal-ceramic restorations. However, onearea where full-coverage restorations arefrequently required is in the managementof anterior teeth that have been extensive-

ly damaged through wear. It is also a clini-cal situation in which adequate prepara-tions of teeth for crowns can be difficult toachieve.

Changes Resultant from Wearof the Anterior TeethWear of the maxillary anterior teeth that isslowly progressive generally leads tol ittle change in the position of the incisaledges. This is caused by the continuederuption of the teeth. In adults whose teethdo not wear significantly, an increase in thetotal face height can be expected withi ncreasing age. 4

The continued eruption of the teeth asthey wear is accompanied by coronalmovement of the gingival soft tissues andthe underlying alveolar bone. This resultsin an increased display of the soft tissuesaround the teeth (Fig 9-7). Patients withslowly progressive wear of the teethgenerally do not suffer loss of occlusalvertical dimension. However, dentistscommonly diagnose individuals who haveworn teeth as having lost occlusal vertical

11 3


dimension. In such situations, it is morelikely that the dentist is observing short-ened teeth accompanied by the increaseddisplay of the gingival tissues.

Where the teeth are short and worn andrequire restoration, there can be difficultyi n achieving adequate retention andresistance form in the preparation whilecreating sufficient space incisally for anadequate thickness of restorative material.Crowning worn anterior teeth withoutmaking any attempt to increase theirlength will achieve little esthetic improve-ment. Furthermore, reducing worn teethstill further in height in order to accommo-date a crown is inappropriate.

Methods of Creating Spacefor the Restoration of WornAnterior Teeth

There are a number of ways to create or re-create space for the restoration of worn an-terior teeth. Classically these have beenbased on altering the occlusal relationshipbetween the mandible and the maxilla. Thefirst method involves adjustment of the oc-clusion in order to change the jaw relation-ship while maintaining the existing occlusalvertical dimension. The second method ofcreating space is by the traditionally some-what controversial method of increasingthe vertical dimension of occlusion.

Creating Space by OcclusalAdjustmentOcclusal adjustment for the purpose ofcreating space is only considered whenthe anterior teeth require restoration, thereis a lack of space, and the posterior denti-tion is reasonably intact. The patient must

exhibit a discrepancy between their retrud-ed axis (RAP) and their intercuspal posi-tions (ICP). Furthermore, the discrepancybetween these two positions must be as-sociated with a significant translation of thecondyles between the two jaw positions.These are individuals who are character-ized as having discrepancies between theRAP and the ICP that have a large hori-zontal component and a smaller verticalcomponent.

A new position of closure (intercuspalposition) is created by adjusting the oc-clusal surfaces of the posterior teeth suchthat all the teeth meet evenly in theRAP but at their original vertical dimensionof occlusion. When there is a significantamount of condylar translation betweenthe RAP and the ICP, elimination of the dis-crepancy by occlusal adjustment will leadto an increase in the overjet. This can, un-der suitable circumstances, create suffi-cient space, and restoration of the wornanterior teeth is facilitated.

The adjustment of the dentition is notalways straightforward or predictable.Before it is carried out, it should be re-hearsed on a set of study casts accuratelymounted in a semiadjustable articulator.The occlusal adjustment should create anew ICP that coincides with the RAP.However, the vertical dimension in thisnew position of closure must be the sameas in the old ICP. If this is not achieved, thepatient is unlikelyto adoptthe new ICP andwill continue to use their old one.

This can be a useful technique but ob-servation over a period of years indicatesthat the number of patients who possessthis type of discrepancy is relatively small.

11 4

Methods of Creating Space for the Restoration of Worn Anterior Teeth

Increasing the VerticalDimension of OcclusionAltering an individual's vertical dimensionof occlusion has always been a somewhatcontentious procedure.6 The reasons forthis are hard to discern but are likely tohave originated in complete dentureprosthodontics. Although there is still littleresearch validating increasing the occlusalvertical dimension for restorative purpos-es, observation and clinical experience in-dicate that where moderate changes aremade to the vertical dimension, coupledwith a stable posterior occlusion and rea-sonable anterior guidance, little adapta-tion is required on the part of the patient. 3

The process of increasing the occlusalvertical dimension has two primary func-tions in the restoration of worn anteriorteeth. First, it creates space for the resto-rations and, second, it provides an oppor-tunity for leveling a disturbed plane ofocclusion. One limiting factor with thisapproach is that all the teeth in one archand often the majority of the dentition re-quire restoration to provide occlusal con-tacts at the new vertical dimension of oc-clusion. The second limiting factor is thatas the vertical dimension is increased, themandible comes to lie in a more posteriorposition and the overjet is relatively in-creased. The relationship can becomesuch that it is impossible to maintain con-tacts on closure between the incisal edgesof the mandibularteeth and the palatal sur-faces of the maxillary anterior teeth. This isundesirable because it becomes impossi-ble to develop useful anterior guidance.Because of these factors, the amount ofspace that can be created by this means issometimes limited.

I f esthetic restoration is to be achieved,surgical crown lengthening is frequently

used adjunctively prior to restoration. Thisexposes more of the tooth to allow the de-velopment of good retention and resis-tance form in the preparations and also al-l ows the restoration to be longer gingivally.It is also helpful in reducing the amount ofsoft tissue that the patient tends to display.The increased display of soft tissues is theresult of the continued eruption of thewearing teeth.

However, there is an adverse cosmeticeffect of surgical crown lengthening.Apical repositioning of the soft tissuesmeans that the marginal tissues come tol ie on a relatively narrow portion of thetooth. This produces wider embrasurespaces that the crowns are unable to con-ceal without overcontouring. This can re-sult in "black triangles" between the teeth(Fig 9-8). It is one of the significant disad-vantages of traditional reconstruction in-volving crown lengthening. A further dis-advantage is the overall time involved forboth the patient and the dentist in makinga full reconstruction.

Relative Axial Tooth MovementAn alternative approach is to employ rela-tive axial tooth movement to reverse thepositional changes in the teeth and softtissues that have taken place as theteeth have worn. Dahl and his coworkersdescribed the technique nearly a quarterof a century ago. It is surprising that it hastaken so long for it to be accepted bythe dental profession.

In his original paper, Dahl describedthe treatment of elderly patients whosemaxillary anterior teeth were worn. 3 Hiswish was to restore these teeth withcrowns but there was inadequate space.The posterior dentitions in these patients

11 5


Fig 9-8 Widened embrasure spaces as a result ofcrown-lengthening surgery.

were considered to be stable and not inneed of restorative treatment. Anteriorbite planes made in chrome-cobalt wereconstructed. These were removable appli-ances that in function provided occlusionforthe mandibular anteriorteeth while sep-arating the posterior teeth. The patientswore these appliances on a full-time basisfor periods in excess of 3 months.Eventually the posterior teeth were foundto be in occlusion whilethe mandibularan-terior teeth still contacted the appliance.Consequently, when the appliance was re-moved, the posteriorteeth were still in con-tact but sufficient space had been createdanteriorly to facilitate restoration of themaxillary anteriorteeth. Dahl quantified thechanges that took place, indicating that inolder patients, creation of the space wasprimarily dependent on intrusion of theteeth in contact with the appliance. Inyounger patients, although intrusion of theteeth in contact with the appliance oc-curred, there was also some continuederuption of the teeth that were out of con-tact. 8, g A further advantage was that thegingival tissues accompanied the axialtooth movement. Consequently, the need

for surgical crown lengthening prior to therestorative procedures was significantly re-duced.

Over the years, Dahl's original principlehas been applied in a variety of clinicalsettings. Early on, it was found that patientcompliance, and therefore speed of treat-ment, could be improved by making appli-ances that were cemented to the teeth. 2These were constructed in cast-nickelchromium and cemented to the teeth us-ing a glass-ionomer cement.

More recently, the definitive prosthesishas been used to produce the relativeaxial tooth movement. Figure 9-9 showsan adhesive fixed partial denture, which,as a consequence of the thickness of theretainers, prevented contacts between themajority of the teeth. Full contact of all theteeth was reestablished within 7 weeks ofthe fixed partial denture being cemented.The patient remained comfortable duringthis time.

Composite resin is being used increas-ingly to restore worn teeth and inducerelative axial tooth movement to re-createappropriate space for the restored tooth.Figures 9-10 to 9-12 show two mandibularincisors worn by a combination of ceram-ic and parafunctional activity. The wornmandibular anterior teeth were restoredwith directly placed composite resinrestorations. The maxillary central incisorswere restored provisionally with metal-acrylic resin crowns. The mandibular in-cisors were restored to an appropriatelength and the dentition left to undergorelative axial tooth movement.

11 6

Conclusions

Fig 9-9 An adhesive fixed partial denture using rel-ative axial tooth movement to allow coverage of theocclusal surfaces of the abutments without priortooth preparation.

Fig 9-10 Mandibular incisors worn against ceram-i c surfaces on the maxillary central incisors.

Fig 9-11 The worn mandibular incisors restoredwith directly placed composite resin restorations.

Fig 9-12 The effect on closure into the ICP.

Conclusions

This chapter has reviewed the importanceof accurate tooth preparation. It has furtherreviewed the traditional methods of restor-ing extensively worn anterior teeth. It hasagain posed the question as to why the

relatively simple technique of deliberaterelative axial tooth movement has not beenmore widely embraced by the dentalprofession.' It is nearly 25 years since thistechnique was first described, and its effi-cacy has been documented repeatedly. 5

11 7


References 5. Ibbetson RJ. Tooth surface loss. 9. Treatmentplanning. Br Dent J 1999;186:552-558.

1. Dahl BL, Krogstad O. Long-term observations ofan increased occlusal face height obtained by acombined orthodontic/prosthetic approach. JOral Rehabil 1985;12:173-176.

2. Dahl BL, Krogstad O. The effect of a partial biteraising splint on the occlusal face height. An x-ray cephalometric study in human adults. ActaOdontol Scand 1982;40:17-24.

3. Dahl BL, Krogstad OK, Karlsen K. An alternativetreatment in cases with advanced localized at-trition. J Oral Rehabil 1975;2:209-214.

4. Gough MB, Setchell DJ. A retrospective study of50 treatments using an appliance to producel ocalised occlusal space by relative axial toothmovement. Br Dent J 1999;187:134-139.

6. Rivera-Morales WC, Mohl ND. Relationship ofocclusal vertical dimension to the health of the

masticatory system. J Prosthet Dent 1991;65:547-553.

7. Setchell DJ. Conventional crown and bridge-work. Br Dent J 1999;187:68-74.

8. Shillingburg HT, Hobo S, Whitsett LID, Jacobi R,Brackett SE. Principles of tooth preparations. In:Fundamentals of Fixed Prosthodontics, ed 3.Chicago: Quintessence, 1997:119-137.

9. Tallgren A, Solow B. Age differences in adultdentoalveolar heights. Eur J Orthod 1991;13:149-156.

11 8

Chapter 10

The Control and Maintenance of

Dentoperiodontal Relationships in Indirect

Anterior Restorations

Samuele Valerio

I ntroduction Biologic Width

The performance, clinical integration, andesthetic qualities of indirect restorationsare the result of effective multi-disciplinarycare and the meticulous execution of each

phase of treatment.

Patient Management

I nitial patient management is fundamentalto the success of all subsequent phases oftreatment. From the outset, the patientmust understand and consent to theaims and methods of the treatment and beencouraged to contribute to a successfuloutcome through close cooperation toachieve, in particular, appropriate plaquecontrol.

With periodontal health established, de-finitive restorative care can be plannedwith expectation of a successful outcome.Success, however, must be viewed interms of long-term stability and patient sat-i sfaction (Figs 10-1 to 10-3).

Fundamental to the preservation of den-toperiodontal relationships is the creationand maintenance of an appropriate biolog-i c width of attached gingivae.15,22,27,29,30Each phase of restorative therapy must re-i nforce rather than threaten the biologicwidth of the attachment apparatus throughthe appropriate management of the mar-

gins of both temporary and definitiverestorations. Such management extendsto location, precision of fit, the quality of thesurface finish, and the emergence pro-flle.23,26,30

Combined Periodontal andOrthodontic Treatment

I n completing preparations for indirectrestorations, the clinical protocol mustmake provision to optimize the architec-ture and thickness of the adjacent peri-odontal tissues. Combined periodontaland orthodontic procedures may form

part of the phases of treatment immedi-ately preceding the completion of thepreparations.

11 9

The Control and Maintenance of Dentoperiodontal Relationships in Indirect Anterior Restorations

Fig 10-1 Preoperative facial view illustrating thecondition and altered morphology of the anteriorteeth and associated periodontal tissues.

Fig 10-2 Postoperative view.

Fig 10-3 Ten-year follow-up illustrating the mainte-nance and improvements in the gingival architec-ture adjacent to the restorations.

The correction of gingival contours,through the orthodontic intrusion andextrusion of teeth, 1,13,16,20,24,40,41 greatlyfacilitates the reconstructive phase of treat-ment, irrespective of the type of restorationplanned forthe patient. With the correctionof the gingival contours, the final phase oftreatment may be undertaken with a de-gree of confidence and much greater easethan may have been otherwise possible( Figs 10-4 to 10-6).

The orthodontic extrusion of, for exam-ple, retained roots is particularly helpfulin the management of traumatized teeth.Extrusion procedures allow the recovery

of periodontal health with the biologicwidth of attached gingivae necessary toensure success of the reconstruction.Extrusion procedures may also preserveand, where necessary, correct the gingivalcc ntours.6.20,21,31-33,39 Orthodontic extru-sion is to be preferred over crown length-ening procedures that result in lessfavorable crown-root relationships anddisharmonies in the gingival architecture.Crown-lengthening techniques are, how-ever, indicated in situations where it is nec-essary to compensate for the effects ofpassive eruption and wear without loss ofvertical dimension. 3,4,8,9,10,14,18,38

1 20

Bonding or No Bonding?

Fig 10-4 Preoperative facial view. Fig 10-5 Appearance following orthodontic align-ment of the anterior teeth.

Fig 10-6 Following intrusion of the right central in-cisor and correction of the gingival contours, the dif-ficulty of the case is greatly reduced.

I n the anterior segments, the mostimportant requirement in the control andmaintenance of dentoperiodontal relation-ships in the provision of indirect restora-tions is the limitation of the extent of thepreparation. The extent of the preparationis dependent on the type of restorationbeing planned, the position and nature ofthe necessary finishing lines, and thespace required to achieve the desiredesthetic result. At the same time, great caremust be exercised to control the occlusalrelationships and the preservation of theremaining tooth tissues, with due regard totheir quality and configuration.

Bonding or No Bonding?

The decision as to whether to selectadhesive restorations is dependent onvarious factors, not least of which is thepossibility of isolating the preparationswith rubber dam to preclude moisture andother contamination at the time of luting.

Of the restorations that may be used inanterior segments and are not reliant onadhesive technology, the choice rangesfrom traditional metal-ceramic restorationsto certain forms of all-ceramic restorations,with restorations of ceramics applied toelectrodeposited metal substructures of-

121


fering a conservative alternative and theadded advantage of excellent marginaladaptation.

Case Presentation

Baseline and Initial TreatmentThe patient, a 53-year-old male, present-ed with advanced wear in the upperanterior segment, requiring rehabilitationby means of indirect restorations to restorefunction and esthetics (Fig 10-7).

Examination revealed that a number ofposterior teeth were missing (Fig 10-8) butthat periodontal health was well main-tained (Fig 10-9). It was concluded thatprevious forms of treatment had beeni nadequate and, as a consequence of pas-sive eruption, the patient had not lostvertical dimension with the wear of theanterior teeth. This was confirmed bysubsequent functional, phonetic, andcephalometric analyses.

Given the decision not to increase thevertical dimension and the height of theclinical crowns to be restored, it was con-sidered appropriate to undertake anteriorcrown lengthening by surgical means.This approach was viewed as necessaryto ensure the clinical performance of theplanned indirect restorations to includereconstruction of the posterior segmentsto correct and stabilize the occlusion.

As the patient presented with well-main-tained periodontal health, no presurgeryprovisional restorations were requiredprior to the crown lengthening (Fig 10-10).

The Reconstructive PhaseSix months after surgery, during whichti me the tissues stabilized, the reconstruc-

tive phase of treatment was planned,based on a diagnostic waxup (Fig 10-11).Such a waxup determines the desiredform and function of the definitive restora-tions. The decision as to which type ofrestoration should be employed was de-layed, pending the 6-month assessment ofthe dentoperiod ontal relationships and arisk analysis of occlusal function and sus-ceptibility to failure. The decision wasmade to restore the teeth with metal-ce-ramic restorations as part of the posteriorfixed partial denture, with the incisors be-i ng restored by means of single-unitrestorations.

Following preparation, which resulted inthe absence of enamel for adhesive bond-ing, and with due regard to the patient'sparafunctional habits, the decision wasmade to restore the incisors by means ofceramic crowns on electrodepositedmetallic substructures. Preparation wascontrolled using silicone indices, whichwere formed on the diagnostic waxup andsectioned axially (Figs 10-12 and 10-13).

During initial preparation, the finishingline was placed somewhat coronal tothe predetermined final position, given thatthe finishing line would eventually be posi-tioned in the gingival crevice for estheticreasons. In this way, the risk of trauma tothe marginal gingivae during initial prepa-ration was minimized (Figs 10-14 and 10-15).

Provisional restorations were then pro-duced, with great care taken to control theanatomic form, occlusal relationships, andcolor. Such restorations facilitate the cre-ation of optimal features in the final restora-tion (Fig 10-16).

122

Case Presentation

Fig 10-7 Preoperative facial view. Fig 10-8 Preoperative occlusal view illustrating theloss of posterior teeth and the wear of the anteriorteeth.

Fig 10-9 Preoperative radiographsshowing the preexisting periodon-tal condition.

Fig 10-10 The anterior segmentfollowing crown lengthening.

1 2 3


Fig 10-11 The diagnostic waxup.

Fig 10-12 The morphology ofthe waxup relative to the pre-operative condition.

Fig 10-13 The morphology ofthe waxup as a guide to thepreparation of the remainingtooth tissues.

1 24

Case Presentation

Fig 10-14 Juxtagingival preparation of the teeth.

Fig 10-16 Temporary restorations produced ac-cording to the waxup.

Fig 10-15 Preliminary preparation to the level ofthe gingival margin.

According to the clinical protocol, thetwo principal aims of the subsequentphase of treatment were:

1. To precisely place and finish the finishingl ines without traumatizing the adjacentgingival tissues and crevice. 5,17,25,35,36

Trauma to the gingival tissues at thisstage of treatment may lead to healingwith unwanted variations in position rel-ative to the finishing line.

2. To open the gingival crevice to allowthe penetration of impression materialbeyond the margin of the preparation,

and thereby obtain an accurate caston which to produce the crowns.Accuracy in the working cast is essen-tial forthe marginal fit of the restorationsbeing provided, and for the creation ofappropriate emergence angles to en-sure a favorable soft tissue response, to-gether with optimum contours for sub-sequent oral hygiene procedures.

Given that the finishing lines of thepreparations had been placed in a juxta-gingival position at the completion of initialpreparation, it was possible to exercise

1 25


Fig 10-17 Placement of the retraction cord at thebase of the gingival crevice.

precise visual control over the subsequentphase of preparation. The use of a No. 000retraction cord, placed delicately in thegingival crevice, provided some apicaldisplacement and dilation of the gingivalcrevice, exposing the margins of thepreparations for accurate impressionrecording (Figs 10-17 and 10-18).Following removal of the retraction cord,the gingival margin adopted its former po-sition, returning the margins of the prepa-rations to their intended subgingival loca-tion, The margin could be located in ajux-tagingival position or just apical to themargin of the conditioned tissue, preserv-ing the possibility of leaving a minimumthickness of nonprepared surface be-tween the margin and the No. 000 cord( Figs 10-19 to 10-21). This is of fundamen-tal importance given that the material used

126

Fig 10-18 The No. 000 cord causes apical dis-placement of the tissues with separation from thepreparation.

for the impression must record the full ex-tent of the necessary detail without push-i ng the cord more apically, thus invadingthe epithelial and connective tissue at-tachment zones. After the preparation hasbeen refined, a second retraction cord isused with the specific aim of dilating thecrevice and facilitating the insertion of thei mpression material. Normally a No. 0 orNo. 1 cord is used and only 50% of its di-ameter must rest in the crevice (ie, it mustfloat) (Figs 10-22 and 10-23). Such care insoft tissue management is essential if theepithelial attachment and subjacent con-nective tissues are to be preserved.

Case Presentation

Fig 10-19 Level of the final preparation.

Fig 10-20 Final preparation completed withouttrauma to the gingival tissues.

Fig 10-21

Final preparation of the entire arch.

Fig 10-22 Position of the second cord to complete

Fig 10-23 Successful completion of the soft tissuethe preparation of the tissues prior to recording the

management.i mpression.

12 7


Fig 10-25 Appearance of the impression illustrat-

i ng extent of the impression beyond the margins ofthe preparations.

Fig 10-24 The dentogingival relationship followingremoval of the second cord.

Figs 10-27 and 10-28 Once the gingival tissues have returned to their original position, the margins of the

preparations lie within the gingival crevice.

12 8

Fig 10-26 Features of the cast, including evidenceof the absence of trauma to the gingival tissues.

Case Presentation

Fig 10-29 Postoperative facial view. Fig 10-30 The cemented restorations with favor-able soft tissue relationships and intracrevicular po-sitioning of the margins.

If the retraction cord is forced apically,there will be two negative effects:

1. The gingival tissues will close in overtheretraction cord, obscuring the marginsof the preparations.

2. The

epithelial

attachment

will

bebreached, causing inflammation of thegingival tissues, which may result in lossof esthetic qualities in the completedcase.

The correct position of secondary No. 0or No. 1 retraction cords ensures dilationof the crevice, facilitating the impressionprocedures (Figs 10-24 and 10-25).

Examination of the cast reveals perfectreproduction of the margins of the prepa-rations, with maintenance of the structuralintegrity of the gingival tissues, includingthe interdental papillae. This is evidence ofsuccessful soft tissue management (Fig10-26). If required, the use of retractioncords may be supplemented with chemicalagents, including aluminium potassiumsulphate and ferric sulphate.2,7,11,12,28,37,42

However, if such agents are used, they

must be thoroughly washed away beforerecording impressions, as they may inter-fere with the polymerization of the impres-sion material and the reproduction of de-tail in the cast.

Assuming preoperative health of thegingival tissues, a prerequisite to successin indirect restorations in terms of dento-periodontal relationships, the gingival lev-els will return to their preoperative positionfollowing the impression procedures (Figs10-27 and 10-28). This allows visual con-firmation of the correct positioning of themargins of the preparations, providesopportunity to ensure masking of metallicmargins and any associated discol-orations, and guarantees the stability ofthe dentoperiodontal relationships. In thisway, a favorable esthetic result will be ob-tained, an outcome of particular impor-tance in the anterior segments of themouth (Figs 10-29 and 10-30).

I f the preoperative condition of the gin-gival tissues is less than ideal, particularlyif they are thin, it is unnecessarily invasiveand hazardous to attempt to use more thanone retraction cord. In such situations

129


Fig 10-31 Level of preliminary preparation and itsrelationship with thin gingival tissues.

Fig 10-33 To complete the management of thingingival tissues, a second retraction cord may beplaced interdentally and palatally.

Fig 10-32 The displacement of thin gingival tis-sues following placement of a single retraction cord

is greater than with normal tissues.

Fig 10-34 The ceramic restorations built on elec-trodeposited metal substructures.

Fig 10-35 Review of the case at 3 years.

13 0

Conclusion

the initial retraction cord tends to causemore apical displacement of the gingivaltissues than would be seen when dealingwith tissues of normal thickness (Figs 10-31 and 10-32). A large vestibular displace-ment makes it necessary to extend thepreparation apically from a juxtagingivalposition to ensure a subgingival locationonce the cord has been removed. If re-quired, a second retraction cord may beplaced interdentally and palatally (Fig10-33), allowing complete control of situa-tions complicated by the presence of thingingival tissues (Figs 10-34 and 10-35).

Conclusion

The success of indirect restorations isdependent on the long-term stability of thebiologic width and the clinical and estheticqualities of restorations. Maintenance inclinical service is dependent on three fac-tors: precision in provision, correct posi-tioning of margins, and quality in surfacefinish. These can only be achieved whenaccurate casts are obtained without trau-ma to the adjacent gingival tissues. This isparticularly demanding if the margins ofindirect restorations are to be placed sub-gingivally. In all cases a meticulous multi-disciplinary approach is required to suc-cessfully manage and ensure stability ofdentoperiodontal relationships in the pro-vision of indirect restorations.

1 31


References

1. Atherton JD. The gingival response to ortho-dontic tooth movement. Am J Orthod 1970;58:1 79-186.

2. Baily JH, Fisher DE. Procedural hemostasis andsulcular fluid control. A prerequisite in moderndentistry. Pract Periodontics Aesthet Dent

1995;7:65-75.

3. Becker W, Ochsenbein C, Becker BE. Crownlengthening: The periodontal-restorative con-nection. Compend Contin Educ Dent 1998;19:239-246.

4. Becker W, Ochsenbein C, Tibbetts L, BeckerBE. Alveolar bone anatomic profiles as mea-sured from dry skulls. Clinical ramifications. JClin Periodontol 1997;24:727-731.

5. Benson BW, Bomberg TJ, Hatch RA, HoffmanW Jr. Tissue displacement methods in fixedprosthodontics. J Prosthet Dent 1986;55:

1 75-181.

6. Berglundh T, Marinello CP, Lindhe J, ThilanderB, Liljenberg B. Periodontal tissue reactions toorthodontic extrusion. An experimental study inthe dog. J Clin Periodontol 1991;18:330-336.

7. Bowles WH, Tardy SJ, Vahadi A. Reevaluationof new gingival tetractin agents. J Dent Res1991;70:1447-1449.

8. Bragger U, Lauchenauer D, Lang NP. Surgicallengthening of the clinical crown. J ClinPeriodontol 1992;19:58-63.

9. Coslet JG, Vanarsdall R, Weisgold A. Diagnosisand classification of delayed passive eruption ofthe dentogingival junction in the adult. AlphaOmegan 1977;70:24-28.

10. Dawson

PW.

Evaluation,

Diagnosis

andTreatment of Occlusal Problems. St. Louis:Mosby, 1974.

11. de Camargo LM, Chee WW, Donovan TE.I nhibition of polymerization of polyvinyl silox-anes by medicaments used on gingival retrac-tion cords. J Prosthet Dent 1993;70:114-117.

12. Donowan TE, Gandara BK, Nemetz H. Re-view and survey of medicaments used with gin-gival retraction cords. J Prosthet Dent 1985;53:525-531.

1 32

13. Ericsson I, Thilander B, Lindhe J, Okmoto H.The effect of orthodontic tilting movements onthe periodontal tissues of infected and non-in-fected dentitions in dogs. J Clin Periodontol

1 977;4:278-293.

14. Gargiulo A, Krajewski J, Gargiulo M. Defining bi-ologic width in crown lengthening. CDS Rev1995;88:20-23.

15. Gargiulo AW, Wentz FM, Orban B. Dimensionsof the dentogingival junctions in humans. JPeriodontol 1961;32:261.

16. Gianelly A, Goldman HM. Biologic Basis ofOrthodontics. Philadelphia: Lea and Febiger,1 971:154-157.

17. Hagge MS, Rector TM. Review of periodontalconsiderations and surgical retraction techni-ques for operative dentistry. Oper Dent 1993;18:179-186.

1 8. Herrero F, Scott JB, Maropis PS, Yukna RA.Clinical comparison of desired versus actualamount of surgical crown lengthening. J Perio-dontol 1995;66:568-571.

19. Ingber JS. Forced eruption. Alterations of softtissue cosmetic deformities. Int J PeriodonticsRestorative Dent 1989;9:416-425.

20. Ingber JS. Forced eruption. Part l. A methodof treating isolated one and two wall infrabonyosseous defects-Rationale and case report. JPeriodontol 1974;45:199-206.

21. Ingber JS. Forced eruption. Part II. A methodof treating nonrestorable teeth-Periodontal andrestorative considerations. J. Periodontol 1976;47:203-216.

22. Ingber JS, Rose LF, Coslet JIG. The "biologicwidth"-A concept in periodontics and restora-tive dentistry. Alpha Omegan 1977;70:62-65.

23. Kay HB. Criteria for restorative contours inthe altered periodontal environment. Int JPeriodontics Restorative Dent 1985;5:42-63.

24. Kois J. Altering gingival levels: The restorativeconnection: Part I: Biologic variables. J EsthetDent 1994;6:3-9.

25. Malamed KA. Periodontics and prosthodontics:Goals, objectives and clinical reality. J ProsthetDent 1992;67:259-263.

References

26. Martignoni M, Schonenberger A. Precisionee Contorno nella Ricostruzione Protesica.Berlin: Quintessenz Verlag, 1987:49-66.

27. Maynard JG Jr, Wilson RD. Physiologicdimensions of the periodontium significant tothe restorative dentist. J Periodontol 1979;50:170-174.

28. Nemetz EH and Seilby W. The use of chemicalagents in gingival retraction. Gen Dent 1990;38:1 04-108.

35. Shavell HM. The periodontal-restorative inter-face in fixed prosthodontics: Tooth preparation,provisionalization and biologic final impres-sions. Part I. Pract Periodontics Aesthet Dent1 994;6:33-44.

36. Shavell HM. The periodontal-restorative inter-face in fixed prosthodontics: Tooth preparation,provisional ization and biologic final impres-sions. Part II. Pract Periodontics Aesthet Dent1994;6:49-60.

29. Nevins M, Skurow HM. The intracrevicularrestorative margin, the biologic width, and themaintenance of the gingival margin. Int JPeriodontics Restorative Dent 1984;4:30-49.

30. Parma Benefati S, Fugazzotto PA, Ruben MP.The effect of restorative margins on the post-surgical development and nature of the peri-odontium. Part I. Int J Periodontics RestorativeDent 1985;5:30-51.

31. Pontoriero R, Celenza F, Ricci G, Carnevale G.Rapid extrusion width fiber resection: A com-bined orthodontic-periodontic treatment modal-ity. Int J Periodontics Restorative Dent 1987;7:30-43.

37. Shaw DH, Krejci RF, Cohen DM. Retractioncords with aluminium chloride. Effect on the gin-giva. Oper Dent 1980;5:138-141.

38. Smukler H, Chaibi M. Periodontal and dentalconsiderations in clinical crown extensions: Arational basis for treatment. Int J PeriodonticsRestorative Dent 1997;17:464-477.

39. Valerio S, Crescini A, Pizzi S. Hard and soft tis-sue management for the restoration of trauma-tized anterior teeth. Pract Periodont AesthetDent 2000;12:143-105.

40. Valerio S, Turillazzi P, Coppiardi C. Rand-schluB and Formgebung bei Provisorien. Team

work 1,2/1999;34-40.

32. Reitan K. Some factors determining the evalu-ation of forces in orthodontics. Am J Orthod

1 957;43:32-45.

33. Reitan K. Tissue rearrangement during reten-tion of orthodontically rotated teeth. AngleOrthod 1959;29:105-113.

34. Sanavi F, Weisgold AS, Rose LF. Biologic widthand its relation to periodontal biotypes. J EsthetDent 1998;10:157-163.

41. Vanarsdall RL, Musich DR. Adult orthodontics:Diagnosis and treatment. In: Graber TM, SwainBF (eds). Orthodontics: Current Principles andTechniques. St. Louis: Mosby; 1985:791-885.

42. Weir DJ, Williams BH. Clinical effectiveness ofmechanical chemical tissue displacementmethods. J Prosthet Dent 1984;51:326-329.

133

Chapter 11

Advances in Bonded Ceramic Restorationsfor the Anterior Dentition

Pascal Magne

I ntroduction

The good overall clinical behavior of bond-ed porcelain laminate veneers in terms offracture rates, microleakage, debonding,and soft tissue response is generally wellrecognized and attested to by numerousclinical studies. Continuous developmentsin the field of adhesive restorative tech-niques have permitted significant broad-ening of the original, anticipated spectrumof indications for ceramic laminate ve-neers. New generations of conceptsemerging from biomimetics are now pro-viding the operator with the ability to re-store the biomechanical, structural, andesthetic integrity of compromised anteriordentition. These novel-design, bonded ce-ramic restorations are stress distributorsi nvolving the crown of the tooth as awhole in withstanding occlusal forces andmasticatory function. They can be used inthe treatment of crown-fractured incisorsand the rehabilitation of worn dentitions,thus contributing to two of the majorobjectives of conservative dentistry: maxi-mum preservation of sound tooth struc-ture and maintenance of the vitality of theteeth to be restored. Mastering the basicprinciples of tooth preparation is funda-mental to creating optimum conditions forthe dental ceramist in the construction of

ceramic restorations. The meticulous ap-plication and handling of modern com-posite resins, including latest generationdentin adhesives will, in turn, guaranteethe reliability and longevity of bonding. Therelated diagnostic procedures, sequentialtreatment planning, tooth preparation, andprovisional ization, as well as the final ad-hesive placement procedure, are dis-cussed.

Biomimetic Conceptsi n Restorative Dentistry:Stiffer and Stronger MightNot Be Better

The future of restorative dentistry may begreatly influenced by the emerging inter-disciplinary science of "biomimetics." 42This modern concept involves investiga-tion of both structures and physical func-tions of biologic "composites" and the de-sign of new and improved substitutes. Inrestorative dentistry, biomimetics startswith an understanding of the structure andarrangement of the dental tissues, and thegeometry and stress distribution within theintact tooth under loading. 27,35 Enameland dentin form a "composite" structurethat gives a tooth unique characteristics. 18

Hard enamel protects the soft underlying

1 35

Advances in Bonded Ceramic Restorations for the Anterior Dentition

dentin, while the crack-arresting effects ofdentin, together with the presence of thickcollagen fibers at the dentinoenamel junc-tion, compensate for the inherently brittlenature of enamel.20 This structural andphysical interrelationship between an ex-tremely hard tissue and a relatively pliable,softer tissue gives the natural tooth itsunique ability to withstand masticatoryloads and thermal stresses over a lifetimein clinical service. With improvements inadhesive procedures and the develop-ment of restorative materials, the behaviorof the enamel-dentin complex can be par-tially mimicked bythe combination of com-posite (compliant and adhesive compo-nent) and porcelain (hard shell). 25 Thishigh performance combination has al-ready proved its clinical reliability throughthe success of porcelain laminate veneers. 6,13,15,17,36,37,39 The first applicationwas proposed in the early 1990s, whenAndreasen2 demonstrated that bondedporcelain veneers have sufficient strengthto be used for the restoration of fractured-crown incisors. Examples of the dramaticconsequences of "biomechanical mis-match" (lack of biomimetics) betweentooth and restoration can be found in theprosthodontic literature. The simulated im-pact study by Stokes and Hood 44 showedthe problematic root fracture pattern asso-ciated with extremely stiff and strongrestorations (gold and metal ceramics)whereas teeth with traditional porcelain ve-neers performed similarly to intact teeth.This data calls into question whether newrestorative approaches should aim to cre-ate the strongest restoration or a restora-tion that is compatible with the mechanicaland biological properties of the underlyingdental tissues.

New Classification ofthe Indications for BondedCeramic Veneers

The considerable potential of porcelainveneers is not limited by scientific andobjective parameters related to biologicconsiderations, function, and mechanics.Ceramic laminates provide the clinicianwith a powerful modality with regard toesthetics. Even in those cases in which it isnot the primary objective, esthetics stillrequire special consideration. Modifica-tions of the form, position, and color ofanterior teeth generate significant effectsi n the smile which, in turn, contribute to thepersonality and social life of patients.

I nitially used to treat tooth discolorationof various causes, laminate veneers havebeen increasingly replaced by more con-servative therapeutic modalities such asbleaching, microabrasion and macroabra-sion. Such developments have not, how-ever, led to a decrease in indications forbonded ceramic veneers. In contrast, therange of applications continues to devel-op.

Three principal groups of indicationsmay be identified: tooth discolorationresistant to vital bleaching procedures(Type I), the need for major modificationsin the morphology of anterior teeth(Type II), and the extended rehabilitationof compromised anterior teeth (Type III).Many Type I and II indications correspondto traditional indications for ceramic lami-nate veneers.6-9 Some Type II and III in-dications are recent. 1,4,21,22,24,28,31,33,45,46

Figures 11-1 a to 11-1 h illustrate one end ofthe spectrum of applications for bondedceramic restorations, allowing optimalresults with minimum sacrifice of soundtooth substance. The clinical challenges of

136

New Classification of the Indications for Bonded Ceramic Veneers

Figs 11-1a to 11-1h Case presentation illustrating Type II indications for bonded ceramic restorations.

Fig 11-1a Preoperative view of smile showingtooth migration, multiple diastema, and vertical lossof soft tissue associated with rapidly progressive pe-ri odontitis.

Fig 11-1b Following completion of periodontaltherapy and the orthodontic redistribution of spaces,teeth 13 through 23 were prepared with the objec-tive of shortening the incisors and closing the inter-dental spaces. Specific tooth preparation for hori-zontal insertion of the veneers was carried out.

Figs 11-1c and 11-id Details of the porcelain veneers for teeth 1 1 through 21 characterized by a markedi nterdental extension of contour, creating a vertical proximal contact line.

1 3 7


Fig 11-1e Novel-design restorations improve both

Fig 11-if Note improved smile line with dramaticgingival and dental esthetics through the compen-

effect on patient's persona.sation of soft tissue loss by the use of more opaqueand saturated porcelain in the interdental zone.

Figs 11-19 and 11-1h Follow-up view showing the stability of the result after more than 4 years of clinicalservice. The position of the teeth has been maintained by a bonded palatal splint.

1 38

New Classification of the Indications for Bonded Ceramic Veneers

Figs 11-2a to 11-2d Case illustrating combined indications for bonded ceramic veneers in a patient seek-i ng improved incisal function and enhanced esthetics.

Figs 11-2a and 11-2b Preoperative appearance. Note the angulation of the central incisors.

Figs 11-2c and 11-2d Details of the existing restorations.

1 39


Figs 11-3a and 11-3b The treatment objective was defined using an additive waxup procedure. Thecorresponding sectioned silicone indices are placed intraorally. Note the repositioning of the midline(i nterincisive line) and the preexisting space for the proposed restorations.

the case illustrated in Figs 11-2a to 11-2d

ed coronal fractures (group IIIA; Fig 11-2)provide good examples of mixed indica-tions for bonded ceramic restorations. Thecase is presented in detail in all subse-quent figures in this chapter.

and malformations (group IIIB).

The Additive Waxup andAcrylic Mock-up: EssentialElements of the DiagnosticApproach

Type IType I indications (tooth discoloration re-sistant to vital bleaching procedures) in-clude teeth heavily discolored because oftetracycline therapy (degrees III and IV ac-cording to Jordan and Boksman,16 groupIA) and anterior teeth that present severelyworn incisal edges that subsequently leadto staining of exposed dentin (group IB).

Type IIType II indications (anteriorteeth in adult re-quiring major modifications in morpholo-gy) include peg shaped teeth (group IIA),diastema and interdental triangles to beclosed or reduced (group IIB; see Fig 11-1),and augmentation of incisive length and in-cisive prominence (group IIC; Fig 11-2).

Type IIIType III indications (rehabilitation of com-promised anterior teeth) include extend-

140

Tooth preparation should not be com-menced without having precisely deter-mined the final shape, position, and lengthof the teeth to be restored. Above all else,the diagnostic approach should allow thepatient to visualize, evaluate, and finally ap-prove the treatment objective. 21,32 The firststep always consists of redefining the de-sired morphology of the teeth to be re-stored on study casts (waxup). The secondstage comprises a clinical evaluation of thediagnostic waxup. In most cases, an addi-tive waxup is carried out because the toothvolume has to be redefined through aug-mentation (Figs 11-3a and 11-3b). This pro-vides opportunity to form an acrylic tem-plate directly in the patient's mouth usinga silicone matrix (Figs 11-4a to 11-4c). Thisremovable template can be readily as-

The Additive Waxup and Acrylic Mock-up: Essential Elements of the Diagnostic Approach

Figs 11-4a to 11-4e After tooth surface corrections, an acrylic mockup is used to assess the proposedoutcome.

Figs 11-4a and 11-4b The mockup is produced by placing a silicone matrix filled with uncured acrylicover the patient's teeth.

Fig 11-4c This thin removable mask s left with thepatient for a week. If necessary, the mockup can befixed using unfilled resin and enamel spot etching.

Figs 11-4d and 11-4e In the case in question significant improvements were obtained using this simpletechnique for the correction of tooth length and the smile line.

1 4 1


sessed by the patient (Figs 11 -4c to 11-4e).Any subsequent modifications are incor-porated into the original diagnostic wax-up, thereby allowing the production of anew template. Tooth preparations shouldnot be commenced until the patient hasapproved the diagnostic template.

Tooth Preparation andProvisional Restorations:Fundamental Principles

The adhesive properties and the physico-chemical characteristics of luting compos-i tes allow the tooth-restoration interfaceto withstand substantial stresses. Basedon such thinking, the geometric and me-chanical parameters of tooth preparationare of secondary importance. This facili-tates maximum preservation of sound min-eralized tissue during tooth preparationprocedures and, as a consequence, a veryconservative approach (Figs 11-5a to11-5c). A minimum amount of preparationgeometry is still required, however, to facil-itate the insertion and positioning of a ce-ramic restoration during placement.

Extensive loss of tooth structure (a largeClass IV defect) can be restored by meansof a laminate veneer alone (simplified ap-proach). The provision of a preprostheticcomposite buildup restoration will not con-tribute to the strength of the tooth restora-tion complex, but may be considered to bea contributory resilient component. In thisway, a preexisting Class IV restoration canfunction as a preprosthetic restoration.However, it is important to avoid a largemass of composite under a porcelain ve-neer restoration because there are still sig-nificant concerns regarding the cumula-tive effects of the curing contraction and

high thermal expansion of certain com-posite resins. The latter has been shown tohave a significant influence on the devel-opment of postbonding flaws when usedas a thick lute,3,30,34 and to suffer margin-al leakage when placed as a complete ve-neer. 19

Existing Class III restorations should becarefully examined for their quality andneed to be replaced. To avoid the unnec-essary sacrifice of mineralized tissue, prox-imal preparation margins may be locatedwithin the bulk of an interdental compositerestoration. When the effects of thermalstresses are considered, partial or totalwrap-around of preexisting compositerestorations is indicated. 23

I t is recommended that a cervical cham-fer be formed, without internal line angles,following the scalloped gingival contour.The insertion of a thin gingival retractioncord (Gingibraid Oa, VanR) facilitates thistask by highlighting the gingival margincontour. The preparation instrument iskept a constant distance away from thecord (approximately 0.5 mm), leading tothe formation of a juxtagingival margin.Systematic incisal/proximal wrap-aroundis recommended. The extent of this wrap-around is dependent on the presentingproblem and the prosthetic objective. Ifmajor modifications of form or the closureof diastema is planned, an extensive wrap-around is essential (see Fig 11-1). In a pho-to-elastic study, the authors underline theimportance of incisal and interdental over-l ap, which appears to provide superiorintrinsic resistance because of favorablestress distribution within the restoration. 14

This approach offers many advantages, fa-cilitating treatment and, in particular, theplacement of the final restorations (stabi-lization of the laminate veneers and easy

142

Tooth Preparation and Provisional Restorations: Fundamental Principles

Figs 11-5a to 11-5d Preparation of the teeth.

Fig 11-5a Preparation guided by the silicone in-

Fig 11-5b Preparation of the left maxillary centraldices to conserve intact tissues.

i ncisor (21) was relatively extensive given its buccalpositioning.

Fig 11-5c Preparation of the mandibular incisors.

Fig 11-5d

Round-ended, tapered burs (D6 No.235 and 237, Intensiv, Grancia, Switzerland) usedto complete the preparations.

143


access to all the margins during the bond-ing procedure). Additionally, incisal cover-age significantly enhances the opportuni-ties available to the dental ceramist with re-spect to the form and emergence profile ofthe future restoration, as well as improvedesthetic definition of the porcelain in themost crucial incisal zone.

There now exists scientific evidence re-garding the type of incisal finishing lineto be recommended as a function of thetype and amount of incisal overlap. 22

Because of the geometry and elastic mod-ulus of mineralized tooth structures, a con-centration of tensile stresses occurs in theregion of the palatal concavity of intactteeth. 35 Long chamfers extending into thepalatal concavity are contraindicated be-cause thin extensions of ceramic will beplaced in the area of maximum tensilestresses. Minichamfers or even butt mar-gins are generally recommended, notablyin the presence of moderate crown frac-tures or severe wear. 22

Most of all, it is essential to producepreparations without sharp angles. Thequality of the preparation (smooth con-tours and an absence of undercuts) and fi-nal impression significantly influences thework of the dental ceramist, leading to aminimal use of die spacer, thus signifi-cantly reducing the risk of postbondingcracks.3,30,34

The Importance of Waxups forEnamel PreservationNeural tissues and enamel are the mostspecialized tissues in the body. The factthat enamel is "etchable" makes it ex-ceedingly precious to the clinician. Thelong-term success of enamel-bonded por-celain veneers is evidence of the value of

enamel. However, tooth preparation tech-niques for laminates have not alwayspromoted the preservation of enamel.Reduction burs with calibrated diamondrings have been proposed to cut enamel tocontrolled depths relative to the preexist-i ng tooth surface. When enamel is initiallythin, reduction based on such depth cutsmay lead to substantial exposure of dentin.I n cases in which the enamel is thin, the ve-neershould aim to restore the original formof the tooth. Therefore, a diagnostic waxupreproducing the original form of the toothshould be used as a reference for tooth re-duction (ie, the use of silicone matricessectioned horizontally in the midsection ofthe tooth; Fig 11-5a). 21 This simple proce-dure will save a significant amount ofsound tissue, both enamel and the criticaldentinoenamel junction. To ensure accu-racy of the silicone guide and optimal in-traoral repositioning, the silicone materialshould be polymerized on the study castunder a pressure of 4 atm.

Three different diameters of burs arerecommended (Fig 11-5d), D6, 235, and237 (Intensiv) or 856L014, 856L016, and856L020 (Brasseler, Savannah, GA). Thethinnest bur is used first to prepare proxi-mal reduction grooves. The medium-sizedbur is then used to produce facial reduc-tion grooves. Gross axial reduction is bestachieved using a larger bur to preventrepenetration into the grooves. In this way,uneven, "wavy" surfaces can be avoided.A uniform space of at least 0.7 mm with aminimum of 1.5 mm incisal clearanceshould be produced using this method, al-lowing for the same thickness of ceramicalong the proximal and axial aspects of thepreparation.

1 44

Elaboration Techniques and Configuration of the Ceramic Workpiece

Preparations for Diastemaand the Management of"Black" Interdental TrianglesCases in which diastema or black inter-dental triangles are to be closed requireextended interproximal preparation to al-low the ceramist to produce a progressiveemergence of the interdental extension(see Fig 11-1). 4 Such situations necessitatecareful planning of the path of insertion ofthe future laminate veneer. It is thereforerecommended that diagnostic (trial)preparations on study casts be undertak-en. In cases in which there has been gin-gival recession, a horizontal path of inser-tion is required to preserve the coronaltooth structure, given the reduced diame-ter of the tooth in the cervical area. 4

I mmediate Dentinal BondingIf a substantial amount of dentin has beenexposed during preparation, the applica-tion of a dentinal bonding agent (DBA) isrecommended. Clinically, two methodsmay be used to ensure effective dentinaladhesion when placing indirect resin-bonded restorations. The first, convention-al approach consists of delaying the appli-cation of the DBA, le, acid etching followedby the application of the primer and bond-i ng resin luting immediately prior to place-ment of the veneer. To avoid incompleteseating of the restoration, it is usually rec-ommended to leave the adhesive resin un-cured when placing the veneer. However,loading of the luting composite during theseating of the veneer may cause the dem-ineralized collagen fibers to collapse andthereby adversely affect cohesion withinthe adhesive interface. 11,12,26 A second al-ternative approach has been proposed tooptimize the DBA application. 5.38 Given

that DBA appears to have more potentialfor adhesion when applied to freshly pre-pared dentin, its application should occurimmediately after the completion of toothpreparation and priorto recording the finalimpression. A substantial clinical advan-tage of this precautionary measure is thatthe pulp-dentin complex is protected andsensitivity and bacterial leakage are re-duced during the provisional phase. Theuse of a filled adhesive resin (Optibond FL,Kerr) may have particular advantages inthis approach.

Production of Provisionals andTemporary CementationThe provisionals are produced in the sameway as the diagnostic mockup, ie, using amold of acrylic resin and a silicone matrix.Because of the extreme fragility of provi-sional veneers, it is not recommended thatthey be mechanically polished. A light-cure glazing resin may be used instead(Palaseal, Kulzer). Esthetic and comfort-able provisionals can be obtained usinglayering techniques such as the intraoralapplication of the laboratory sandwichtechnique. 29,32 After spot etching of theenamel, temporary luting is achieved us-i ng unfilled adhesive resin that may be lightcured through the restorations. This tech-nique is not applicable in cases of imme-diate dentinal bonding.

Elaboration Techniques andConfiguration of the CeramicWorkpiece

I n most cases, ceramic laminate veneersare used to restore the enamel portion ofteeth. Log cally, ceramics are the materials

14 5


of choice because their physical charac-teristics are close to those of enamel. Thisis in contrast to composite resins withphysical properties that more closely re-semble those of dentin. Composite lami-nates do not appear to be able to eitherrestore the rigidity of the intact tooth 40 orto match the performance of ceramicsi n terms of marginal seal atthe dentin-com-posite interface. 19 Numerous systems ex-ist for the production of ceramic veneers.The correct use of a given system is morei mportant than the selection of the systemitself. The simple refractory die technique(eg, Ducera-Lay refractory die material,Duceram) is generally recommended be-cause it does not require expensive de-vices or materials and has been found toresult in satisfactory outcomes even in themost demanding of clinical situations. 33

Most traditional feldspathic ceramicsexhibit higher tensile strength than enam-el. The ultimate success of the techniquerelies on the adhesion obtained betweenthe luting composite and the ceramic sub-strate and between the luting compositeand the mineralized dental tissues. It is,therefore, of primary importance to selectceramics that can be effectively etched,such as the porcelain normally used inporcelain-fused-to-metal techniques (eg,Creation, Klema).

Delamination and chip fractures arethe most commonly reported reasons forthe failure of veneers. Delamination is stillpoorly understood and may even occuri n homogenous, well-fined porcelain . 43 I t istherefore most important to obtain the bestpossible surface characteristics in theceramic during glazing or mechanicalpolishing. It is also important to bear inmind that a sufficient and even thicknessof ceramic, together with a minimum thick-

ness of luting composite, will provide therestoration with the most favorable config-uration with respect to crack propensity(ie, a ceramic-composite ratio of thick-nesses > 3.0). During laboratory proce-dures, die spacer should be used sparing-ly to avoid unnecessary luting compositethickness. A minimum of 0.6 mm of ce-ramic is required for an average compos-ite thickness of 200 gm. This poseschallenges for the clinician during toothpreparation. Special steps and techniquesmust be used in cases in which theenamel has suffered wear. Since therestoration should aim to re-create the formof the tooth, worn surfaces may requirerelatively little preparation. As alreadymentioned, the use of a diagnostic waxupand subsequently silicone matrices duringtooth preparation (Fig 11-5a) is particularlyimportant in such cases to ensureappropriate thicknesses of composite andceramic. 21

Try-in and Placement ofBonded Ceramic Veneers

The placement of ceramic restorationscan be preceded by a try-in. When a re-fractory die technique is used, the restora-tion should be as complete as possiblebefore try-in because only low-fusing ce-ramics can be added once the refractorydie material has been sandblasted away.

As far as the success of the final bond-ing is concerned, it relies heavily on thepreparation and conditioning of the sur-faces involved. In most cases, the bondingprocedure can be carried out using al ight-cured composite because porcelainveneers rarely exceed a thickness of1 mm and are generally translucent. The

146

Try-in and Placement of Bonded Ceramic Veneers

physicochemical properties of dual-curedproducts cannot be considered optimalbecause there is a compromise betweenthe degree of conversion and color stabili-ty.10 I n veneering, the indications for thesematerials remain limited to ceramic ve-neers of an extreme facial thickness (> 2mm) and to situations where opaque ve-neers have been selected (eg, cases of se-vere discoloration). Traditional light-curedmaterials offer a considerable advantagebecause of their ease of manipulation (un-li mited working time and ideal consisten-cy). One should select a relatively neutralshade of composite to enhance translu-cency and permit even light distribution( Fig 11-6a). Such shades should also en-hance the inherent luminosity (fluores-cence) of the restoration. As with all adhe-sive techniques, the final insertion of therestorations has to be preceded by isola-tion of the area (Fig 11-6b) using rubberdam or at least a retraction cord if the ap-plication of rubber dam proves extremelydifficult. A last try-in of the laminate is car-ried out under rubber dam. The bondingprocedure is then performed, following theplacement of segments of transparent ma-trices and interdental wedges (Fig 11-6b).Wedges facilitate the insertion of the lami-nate veneer and prevent the accumulationof excess luting composite in the inter-proximal area. Final seating of the restora-tion, however, is achieved after removal ofthe matrices and wedges.

Conditioning of the CeramicSurfaces to be BondedFollowing activation of the silane solution,( generally performed by mixing two com-ponents) the surface of the ceramic veneerto be bonded is etched for 90 seconds

with 10% ammonium bifluoride gel(Biodent Retentionsgel, Dentsply/DeTrey).This procedure has to be performed usingstrictly controlled protective measures,comprising rubber gloves, face mask, pro-tection glasses, and specially designed in-strumentation (Fig 11-6c). After abundantrinsing (including 2 to 3 minutes in 95% al-cohol in an ultrasonic bath) and drying, theetched ceramic surface is covered with theactivated silane solution (eg, Silicon P,Kulzer). The laminate is then placed in afurnace to dry at 100°C for at least 1minute. This eliminates water and othercontaminants and enhances the conden-sation of the silane on the ceramic sur-face. 41 Thermal treatment also can be car-ried out using a hair dryer.

Preparation of theTooth Surface to be BondedThis comprises 30 seconds of etchingwith 37% phosphoric acid (Ultratech,Ultradent), assuming the prepared surfaceis largely enamel. However, if a consider-able area of dentin has been exposed dur-i ng tooth preparation, it is suggested that adentinal adhesive be applied, strictly in ac-cordance with the manufacturer's direc-tions for use. As already indicated, a rec-ommended approach comprises the ap-plication of the dentinal adhesive prior totaking the final impression (immediatesealing of the dentin). This precautionhelps protect the pulp-dentin complex andavoids any tooth sensitivity during the pro-visional phase. At the time of the finalbonding of the restoration, the adhesive-covered surface should be meticulouslycleaned with pumice. The bonding proce-dure is then limited to the conditioning ofthe prepared enamel.

14 7


Figs 11-6a to 11-6c Preparation for placement of ceramic veneer.

Fig 11-6a The preferred light-cured luting com-posite is translucent and slightly fluorescent( Herculite XVR Incisal LT).

Fig 11-6b The operative field atthe time of placing a veneer ontooth 23.

Fig 11-6c The restoration can be readily handledduring etching and silanization using specially de-signed instrumentation (Accu-Placer, Hu-Friedy) incombination with sticky wax.

Placement of the LaminateVeneerThe adhesive resin is applied to both theconditioned tooth surface and the etchedceramic surface to be bonded, followedby a gentle air blow, but without initiationof polymerization. From that moment on,the operating field should be free fromany intense light (eg, operating light). Ahomogeneous mass of light-cured com-posite is then applied to the inner ceramicsurface. Particular care should betaken to

avoid the incorporation of air bubbles be-tween composite and the veneer. Thiswould create areas of light absorption(gray spots) that would be visible followingcementation. The veneer is slowly seatedwith gentle finger pressure along thei nsertion axis. Gross excesses of compos-ite are then removed with the tip of anexplorer previously impregnated withunfilled adhesive resin. The instrument isguided in a cutting motion parallel to themargin to avoid the removal of composite

148

Conclusions

from the margin. Matrices and wedges areremoved at this stage. The veneer is thenreseated under finger pressure and theremoval of excess material repeated asoften as is necessary. The final seating ofthe laminate veneer occurs when fingerpressure no longer results in the extrusionof composite cement along the margin.A dry brush is then used to eliminateresidual excess resin. Photopolymeriz-ation is performed through a layer of glyc-erin gel (K-Y Jelly, Johnson & Johnson),beginning from the palatal aspect with a90-second exposure (regular curingmode). This is followed by a 90-second ex-posure from the buccal aspect with inter-mittent interproximal exposures. Any ex-cesses of cured adhesive resin are re-moved using hand instruments (scalpeland scaler). The use of rotary instrumentsis not recommended because such instru-ments may damage the margins of thelaminate. When multiple laminate veneersare to be placed, it is best to proceed in asystematic manner, applying the completesequence for bonding (conditioning of theceramic, preparation of the tooth surface,and insertion of the laminate veneer) onetooth at a time. It is not recommended toperform bonding procedures on severalteeth simultaneously.

Final Adjustments and Controlof OcclusionThe occlusion is adjusted, beginning withcentric occlusion (maximal intercuspa-tion). Under no circumstances should thisstep be carried out before the final bond-ing of ceramic veneers, given the high riskof fracture. The functional features of teethrestored with porcelain veneers are identi-cal to those of intact natural teeth.Particular emphasis must be placed onrestoring and maintaining functional ante-rior guidance during mandibular excur-sions (laterotrusion and protrusion) re-gardless of whether this guidance involvesthe newly placed veneer restorations.

Conclusions

The need for preprosthetic interventions(eg, root canal therapy and crown length-ening) and the placement of intraradicularposts can be significantly reduced by theuse of bonded ceramic restorations. Suchrestorations provide a reliable, noninvasiveand economical means of restoring exten-sive elements of the coronal tissues andl ength of teeth in the anterior dentition. Theoutcome of the case presented in this arti-cle is illustrated in Figs 11-7a to 11-7c, withthe appearance after 3 years of clinical ser-vice being shown in Figs 11-7d and 11-7e.

149


Figs 11-7a to 11-7e Postoperative views showing only slight modifications compared to the diagnosticmockup and corresponding situation after 3 years of clinical service.

Figs 11-7a and 11-7b Postoperative intraoral views.

Fig 11-7c Postoperative clinical view of smile.

Fig 11-7d After 3 years of clinical service.

Fig 11-7e After 3 years of clinical service. Note nat-ural effects through sophisticated incisal edge char-acterization (dentinal mamelons and transparentenamel).

150

References

References

1. Andreasen FM, Daugaard-Jensen J, Munks-gaard EC. Reinforcement of bonded crown frac-tured incisors with porcelain veneers. Endod

Dent Traumatol 1991;7:78-83.

2. Andreasen FM, Flugge E, Daugaard-Jensen J,Munksgaard EC. Treatment of crown fracturedi ncisors with laminate veneer restorations. Anexperimental study. Endod Dent Traumatol1992;8:30-35.

3. Barghi N, Berry TG. Post-bonding crack forma-tion in porcelain veneers. J Esthet Dent 1997;9:51-54.

4. Belser UC, Magne P, Magne M. Ceramic lami-nate veneers: Continuous evolution of indica-tions. J Esthet Dent 1997;9:197-207.

5. Bertschinger C, Paul SJ, Luthy H, Scharer P.Dual application of dentin bonding agents: Its ef-fect on the bond strength. Am J Dent 1996;9:115-119.

6. Calamia JR. Clinical evaluation of etched porce-l ain veneers. Am J Dent 1989;2:9-15.

7. Calamia JR. Etched porcelain facial veneers:A new treatment modality based on scientificand clinical evidence. N Y J Dent 1983:53:255-259.

8. Calamia JR. Etched porcelain veneers: the cur-rent state of the art. Quintessence Int 1985;16:5-12.

9. Calamia JR. The current status of etched por-celain veneer restorations. J Indiana Dent Assoc1993;72:10-15.

10. Darr AH, Jacobsen PH. Conversion of dualcure luting cements. J Oral Rehabil 1995;22:43-47.

11. Dietschi D, Herzfeld D. In-vitro evaluation ofmarginal and internal adaptation of class II resincomposite restorations after thermal and oc-clusal stressing. Eur J Oral Sci 1998;106:1033-1042.

12. Dietschi D, Magne P, HolzJ. Bonded to tooth ce-ramic restorations: In vitro evaluation of the effi-ciency and failure mode of two modern adhe-sives. Schweiz Monatsschr Zahroned 1995;105:299-305.

13. Fradeani M. Six-year follow-up with Empressveneers. Int J Periodontics Restorative Dent1998;18:216-225.

14. Highton R, Caputo AA, Matyas J. A photoelasticstudy of stress on porcelain laminate prepara-tions. J Prosthet Dent 1987;58:157-161.

15. Horn HR. Porcelain laminate veneers bonded toetched enamel. Dent Clin North Am 1983;27:671-684.

16. Jordan RE, Boksman L. Conservative vital

bleaching treatment of discolored dentition.Compend Contin Educ Dent 1984;5:803-808.

17. Kourkouta S, Walsh TT, Davis LG. The effect ofporcelain laminate veneers on gingival healthand bacterial plaque characteristics. J ClinPeriodontol 1994;21:638-640.

18. Kraus BS, Jordan RE, Abrams L. Histology ofthe teeth and their investing structures. In:Dental Anatomy and Occlusion. Baltimore:Williams and Wilkins, 1969:135.

19. Lacy AM, Wada C, Du W, Watanabe L. In vitromicroleakage atthe gingival margin of porcelainand resin veneers. J Prosthet Dent 1992;67:7-10.

20. Lin CP, Douglas WH. Structure-property rela-tions and crack resistance at the bovine dentin-enamel junction. J Dent Res 1994;73:1072-1078.

21. Magne P, Douglas WH. Additive contour ofporcelain veneers: A key-element in enamelpreservation, adhesion and esthetic for the ag-i ng dentition. J Adhes Dent 1999;1:81-92.

22. Magne P, Douglas WH. Design optimization andevolution of bonded ceramics for theanterior dentition: a finite element analysis.Quintessence Int 1999;30:661-672.

23. Magne P, Douglas WH. Interdental design ofporcelain veneers in the presence of compos-ites fillings: Finite element analysis of compositeshrinkage and thermal stress. Int J Prosthodont2000;13:117-124.

24. Magne P, Douglas WH. Optimisation des con-cepts mecanique en medecine dentaire esthe-tique. Inf Dent 1999;81:373-381.

151


25. Magne P, Douglas WH. Optimization of resili-ence and stress distribution in porcelain ve-neers for the treatment of crown-fractured in-cisors. Int J Periodontics Restorative Dent1999;19:543-553.

26. Magne P, Douglas WH. Porcelain veneers:Dentin bonding optimization and biomimetic re-covery of the crown. Int J Prosthodont 1999;12:111-121.

27. Magne P, Douglas WH. Rationalization of es-thetic restorative dentistry based on biomimet-ics. J Esthet Dent 1999;11:5-15.

28. Magne P, Holz J. Restoration of the anteriorteeth. The principles, indications and limits ofthe treatment techniques [in French]. SchweizMonatsschrZahroned 1994;104:1246-1258.

29. Magne P, Holz J. Stratification of compositerestorations: Systematic and durable replicationof natural aesthetics. Pract Periodont & AesthetDent 1996;8:61-68.

30. Magne P, Kwon KR, Belser U, Hodges JS,Douglas WH. Crack propensity of porcelain lam-i nate veneers: A simulated operatory evaluation.J Prosthet Dent 1999;81:327-334.

31. Magne P, Magne M, Belser U. Natural and

restorative oral esthetics. Part II: Esthetic treat-ment modalities. J Esthet Dent 1993;5:239-246.

32. Magne P, Magne M, Belser U. The diagnostictemplate: Key element of a comprehensive es-thetic treatment concept. Int J PeriodonticsRestorative Dent 1996;16:561-569.

33. Magne P, Perroud R, Hodges JS, Belser UC.Clinical performance of novel design porcelainveneers for the recovery of coronal volume andl ength. Int J Periodontics Restorative Dent2000;20:441-457.

34. Magne P, Versluis A, Douglas WH. Effect of lut-i ng composite shrinkage and thermal loads onthe stress distribution in porcelain laminate ve-neers. J Prosthet Dent 1999;81:335-344.

35. Magne P, Versluis A, Douglas WH. Ratio-nalization of incisor shape: Experimental-nu-merical analysis. J Prosthet Dent 1999;81:345-355.

36. Meijering AC, Roeters FJ, Mulder J, CreugersNH. Patients' satisfaction with different types ofveneer restorations. J Dent 1997;25:493-497.

37. Nordbo H, Rygh-Thoresen N, Henaug T. Clinicalperformances of porcelain laminate veneerswithout incisal overlapping: 3 -year results. JDent 1994;22:342-345.

38. Paul SJ, Scharer P. The dual bonding tech-nique: a modified method to improve adhesiveluting procedures. Int J Periodontics RestorativeDent 1997;17:536-545.

39. Peumans M, Van Meerbeek B, Lambrechts P,Vuylsteke-Wauters M, Vanherle G. Five-year clin-ical performance of porcelain veneers.Quintessence Int 1998;29:211-221.

40. Reeh ES, Ross GK. Tooth stiffness with com-posite veneers: A strain gauge and finite ele-ment evaluation. Dent Mater 1994;10:247-252.

41. Roulet JF, Soderholm KJ, Longmate J. Effectsof treatment and storage conditions on cer-aramic/composite bond strength. J Dent Res1995;74:381-387.

42. Slavkin HC. Biomimetics: Replacing body partsis no longer science fiction. J Am Dent Assoc1 996;127:1254-1257.

43. Smith TB, Kelly JR, Tesk JA. In vitro fracturebehavior of ceramic and metal-ceramic restora-tions. J Prosthodont 1994;3:138-144.

44. Stokes A, Hood JAA. Impact fracture character-istics of intact and crowned human central in-cisors. J Oral Rehabil 1993;20:89-95.

45. Walls AW. The use of adhesively retained all-porcelain veneers during the management offractured and worn anterior teeth: Part 1.Clinical technique. Br Dent J 1995;178:333-336.

46. Walls AW. The use of adhesively retained all-porcelain veneers during the management offractured and worn anterior teeth: Part 2.Clinical results after 5 years of follow-up. Br DentJ 1995;178:337-340.

152

Chapter 12

Computer Veneers with the Cerec 3

Andreas Bindl, Wibke Apholt, and Werner H. Mormann

Introduction

The Cerec 3 CAD/CAM system (Sirona,Bensheim, Germany) was presented to thedental community in February 2000 as anadvanced version of the Cerec 2 full-ce-ramic restoration production system (Fig12-1). The Cerec software is now WindowsNT-formatted and runs on personal com-puters. 3 A modified, powerful PC has beeni ntegrated intothe CAD unit, providing veryshort computing times for the optical im-pression, restoration design, matching oftwo optical impressions to include func-tional occlusal information, and saving thedata for documentation. 6 The separateCAM unit is equipped with one cylindricaland one conical diamond-coated bur (Fig12-2). This new grinding system allows theshaping of complex restoration forms, withhigh precision adaptation to any kind oftooth preparation 3 ( Fig 12-3). Communica-tion between the CAD and the CAM unit iswireless via radio. Simple buccal coverageCAD/CAM veneers have been producedusing the Cerec 1 system since 1986. Theextended machining mode of Cerec 2 hasextended the system to include the buccal,l ateral, and incisal aspects of anteriorteeth. 4 Cerec 3 has even greater versatility

Fig 12-1 3D-acquisition-Computer Aided Design(CAD) operating unit (right) and Computer AidedMachining (CAM) form-grinding unit (left).

i n the production of veneers even on com-plex preparations, giving natural morphol-ogy and high accuracy of fit. To illustratethe manufacture of a Cerec 3 CAD/CAMveneer, a case is presented showing all theclinical and technical steps.

1 53


Fig 12-2 Machining of a ceramicl aminate veneer with cylindricaland conical diamond-coated burscutting simultaneously.

Fig 12-3 The range of Cerec 3restorations. From top left, full ce-ramic inlay, onlay, veneer, anteri-or, and posterior crowns.

Clinical Case

An 18-year-old female patient presentedwith caries-free teeth, including a partiallyerupted left maxillary canine in infraocclu-sion as a result of early extraction of theprimary canine. This extraction created op-portunityforthe premolarsto move mesial-l y, thus reducing the space forthe eruptingcanine (Figs 12-4 and 12-5). The patientwas unhappy with the resulting esthetics

but refused orthodontic treatment be-cause she was seeking an immediate so-lution to the problem. A proposal wasmade to manage the situation with a mini-mally invasive Cerec 3 veneer, which thepatient accepted. To make provision for es-thetic add-on layers of veneering ceramic,it was decided to produce the veneer indi-rectly with the optical impression beingtaken from a plaster cast.

154

Clinical Case

Fig 12-4 Lateral aspect of the partially eruptedleft maxillary canine standing in infraocclusion.

Fig 12-5 Incisal view of the left maxillary canineill ustrated in Fig 12-4.

Shade SelectionMark II ceramic' (Vita, Sackingen,Germany) was chosen for this case. TheCerec 3D-Master shade guide (Vita) wasused to select the basic color of the ce-ramic block. The monochromatic CerecVitabloc shade 2M2C was found to offerthe best match. Individual shade charac-teristics including higly colored areas atthe neck of the tooth and areas of hightranslucency incisally were planned.Vitadur Alpha (Vita) ceramic was used asan add-on veneering material to createtranslucent incisal effects.

Preparation, Impression, andPlaster CastMinimal reduction of the labial enamel, notexceeding 0.4 mm in the cervical area,was sufficient for the construction of theveneer. The cervical margin was placedepigingivally and finished as a chamfer(Fig 12-6). All margins were within enamel.To preserve hard tissue, the incisal marginof the preparation was located along theincisal edge of the tooth rather than being

extended palatally with incisal coverage( Fig 12-7). The proximal margins of thepreparation were placed midproximallyby reducing the proximal contact area byless than 50%. Gingival displacement wasaccomplished using a thin retraction cordinserted into the gingival crevice. The im-pression was recorded using polyetheri mpression material (Permadyne, Espe,Seefeld, Germany).

Provisional RestorationHeliobond (Vivadent, Schaan, Liechten-stein) was applied to the unconditionedsurface of the preparation, followed by alayer of composite restorative material(Tetric-Ceram, Vivadent). The material wasl ight-cured and the surface trimmed andfinished with flexible discs (Sof-Lex, 3M, St.Paul, MN) and an abrasive bristle-brush(Occlubrush, Hawe Neos, Switzerland). Asthe enamel had not been etched, the tem-porary restoration could be readily re-moved with a scaler.

1 55


Fig 12-6 Veneer preparation of the left maxillarycanine as seen in the cast powdered (Cerec pow-der, Vita) for the optical impression.

Computer Aided Design ofVeneerCerec Liquid (Vita) was applied to thepreparation and the neighboring teeth inthe cast obtained from the impression. Athin opaque layer of Cerec-powder (Vita)was sprayed on the treated surfaces topermit high-contrast 3D scanning to ob-tain the so-called "optical impression , 5

(Fig 12-7). Following start-up of the Cerec3 CAD unit, the veneer design mode wasselected,$ the morphological databasewas activated, and the tooth to be ve-neered was entered. The optical impres-sion was recorded using the Cerec 3Dmeasuring camera with the preparationcentered in the middle of the screen, theteeth aligned vertically, and all parts of thepreparation being well focused (Fig 12-7).The mesial and distal reference "equator"l ines were then identified on the adjacentteeth, allowing the proximal positions ofthe neighboring teeth to be entered. The"bottom line" marking of the 3D course ofthe preparation margins was then com-pleted (Fig 12-8). The system then auto-matically proposed the "contact line," rep-

1 56

Fig 12-7 Recording the optical impression of theveneer preparation using the Cerec 3D measuringcamera.

resenting the maximum circumference ofthe veneer, and established the proximalcontacts with the adjacent teeth (Fig 12-9).

The proposed veneer was extendedbeyond the incisal limit of the preparationto form a new incisal edge to the canine.This editing involved drawing the contactl ine according to the envisaged profile ofthe incisal edge of the canine (Fig 12-9).The system then proposed two lines run-ning mesiodistally from the labial surfacesof the adjacent teeth across the veneerpreparation, the upper cross line definingthe upper part of the labial surface of theveneer and the lower cross line definingthe lower part. Both lines were edited tothe particular morphological requirementsof the case (Fig 12-10). The resultant ve-neer design was refined on the screenusing the surface tool. This tool allows theexamination of cross sections of the ve-neer in any direction. The incisal-cervicalcross section line is shown in Fig 12-11.Figure 12-12 illustrates the correspondingcross section through the veneer con-struction. A horizontally orientated mesio-distal cross section line is reproduced in

Clinical Case

Fig 12-8 Bottom line (blue)marking the 3D course of thepreparation margins.

Fig 12-9 Contact line (automa-tically proposed by the CAD sys-tem), representing the maximumcircumference of the veneer.

Fig 12-10 Incisal (yellow) andcervical (blue) cross lines defin-i ng the labial surface of the ve-neer.

Fig 12-11 Vertical incisal-cervi-cal cross section line (white).

Fig 12-12 Incisal-cervical crosssection through the veneer con-struction as marked in Fig 12-11.

157


Fig 12-13 Horizontal mesiodistal

Fig 12-14 Cross section through the veneer construction in thecross section line (white).

mesiodistal direction as marked in Fig 12-13.

Fig 12-15 Machined ceramic lam-i nate veneer ready to be cut off themachining stub.

158

Clinical Case

Fig 12-16 Try-on of the laminate veneer on theplaster cast.

Fig 12-17 Defining the incisal area to be reducedfor the individual buildup.

Fig 12-13 with the corresponding crosssection of the veneer being shown in Fig12-14. When the machining icon is activat-ed, the construction is automatically savedon the hard disc and the user is requestedto insert a ceramic block of adequate size.The system computes the shape of the ve-neer from the data obtained from the opti-cal impression and the selected construc-tion lines.8 During the machining processthe two diamond-coated burs, one cylin-drical and the other cone-shaped, operatesimultaneously. After 10 minutes of formgrinding, the ceramic veneer is presentedready to be cut off the machining stub (Fig12-15).

Esthetic BuildupThe veneer was tried on the plaster castand found to have excellent fit (Fig 12-16).To define the buildup of the veneer, an areacomprising the mesioproximal and the up-per incisal third of the buccal surface wasi dentified with a red pencil (Fig 12-17). Themachined thickness of this portion of theveneer is shown in Fig 12-18. The marked

labial area was then reduced in thicknessby approximately 50% (Fig 12-19) using adiamond bur. Vitadur Alpha veneering ce-ramic (Vita) was used for the buildup (Fig12-20). The incisal portion was formedwith "transparent blue," "opalescent," and"clear" ceramic together with enamel ce-ramic (Figs 12-21 and 12-22). Dentinal ce-ramic, a shade darker than the shade ofthe body of the veneer, was applied to thegingival third (Fig 12-23). After 5 minutes ofdrying, the veneer was fired in a Vacumat40 furnace (Vita) at 950°C (Fig 12-24). Thefired veneer (Fig 12-25) was smoothed andcontoured (Fig 12-26) using a flame-shaped diamond bur. To perfect the es-thetics of the veneer, ceramic paint-onshades (Fig 12-20; Akzent, Vita) were ap-plied to further individualize the surface( Fig 12-27). After a second firing at 850°Cto fix the ceramic shade, a thin layer of ce-ramic glaze was applied to achieve a nat-ural luster (Fig 12-28).Theveneerwasfiredagain at 940°C in the Vacumat 40furnace and tried on the model (Figs 12-29and 12-30). Finally, the internal surface ofthe restoration was sandblasted with

159


Fig 12-18 Machined thickness of the incisal aspectof the veneer.

Fig 12 -20 Vitadur Alpha veneering ceramic (left)was used forthe buildup and Vita Akzent stains andglaze (right) was used for external characterizationof the laminate.

Fig 12-22 The form of the incisal edge was estab-l ished.

1 60

Fig 12-19 Incisal edge manually reduced in thick-ness by approximately 50%.

Fig 12-21 The iricisal portion of the veneer wasformed using transparent, opalescent, and clearveneering ceramic.

Fig 12-23 Dentinal ceramic was applied to thegingival third of the laminate.

Clinical Case

Fig 12-24 The veneer was fired in a Vacumat 40furnace at 950°C.

Fig 12-25T he fired laminate on the cast.

Fig 12-26 The veneer was smoothed and con-toured with diamond burs.

Fig 12-27 Ceramic paint-on stains were applied to

Fig 12-28 After a firing to fix the ceramic stains,further individualize the surface.

a thin layer of ceramic glaze was applied.

161


Fig 12-29 The fired laminate veneer on thecast.

Fig 12-30 The same veneer, inan anterolateral view.

50 Um aluminum oxide to remove any ex-cess glazing ceramic.

Adhesive placementThe provisional veneering composite wasremoved with a scaler and the preparationsurface cleaned with pumice and a rotat-ing brush. After try-in, the internal surfaceof the veneer was etched with 4.9% hy-drofluoric acid (Ceramics Etch, Vita) for 60seconds, silanized for 60 seconds usingMonobond S (Vivadent) and covered inbond (Heliobond, Vivadent). For seatingthe veneer, retraction cord was used to ex-pose the gingival margin, and the mesialand distal interdental spaces were protect-ed with acrylic strips firmly secured withwooden wedges. The enamel was etchedfor 30 seconds with 37% phosphoric acidgel (Ultradent), rinsed off (20 seconds) andthen dried using an air syringe. After ap-plication, allowing 20 seconds of penetra-

tion time, the bonding was blown out to athin layer and light cured for 60 seconds(Heliolux DLX, Vivadent). The veneer wasthen placed using the light reactive basepaste of Variolink Ultra (Vivadent). Lightcuring was achieved by 60-second expo-sures on the buccal and palatal aspects ofthe tooth. 2,7 Excess luting material was re-moved along the proximal marginsusing diamond-coated oscillating files(Proxoshape, Intensiv, Grancia, Switzer-l and) and diamond-coated strips (GC). Themargins were then polished with flexiblediscs (Sof-Lex).

Figures 12-31 and 12-32 show the pleas-ing esthetics of the individualized Cerecveneer relative to the adjacent naturalteeth. The incisal view demonstrates thenew harmonious contour of the buccal sur-face and the altered alignment of the ca-nine (Fig 12-33). The satisfied patient hadgood reason for smiling (Fig 12-34).

162

Clinical Case

Fig 1231 Situation before the veneering of theleft maxillary canine.

Fig 12-32 Cerec laminate veneer providing excel-lent esthetics.

Fig 1233 The incisal aspect after bonding of the

Fig 12-34 Clinical view of smile.veneer.

163


References

1. Datzmann G. Cerec Vitablocs Mark 11Machinable Ceramic. In: Mormann WH (ed).CAD/CIM in Aesthetic Dentistry: Cerec 10 YearAnniversary Symposium. Chicago: Quintes-sence, 1996:205-216.

2. Lutz F, Krejci I. Neue Adhasivsysteme: Schrittezum "Total Bonding." Phillip J 1992;10:445-449.

3. Mormann WH, Bindl A. CEREC 3-A quantumleap for computer-aided restorations: Initial clin-ical results. Quintessence Int 2000;31:699-712.

4. Mormann WH, Bindl A. The new creativity inceramic restorations: Dental CAD-CIM. Quintes-sence Int 1997;27:821-828.

5. Mormann WH, Brandestini M. Die CERECComputer Reconstruction-Inlays, Onlays andVeneers. Berlin: Quintessenz, 1989.

6. Muller H. Correlation and function in Cerec 3.I nt J Comput Dent 2000;3:49-56.

7. Von Meerbeek B, Perdigao J, Lambrechts P,Vanherle G. The clinical performance of adhe-sives. J Dent 1998;26:1-20.

8. Wiedhahn K. The new Cerec 3 veneer program.I nt J Comput Dent 2000;3:57-60.

164

Chapter 13

Esthetic Posterior Indirect Restorations

Jean-Frangois Roulet and Roberto Spreafico

Adhesion-The Basic Principles

With few exceptions, bonding in dentistrymeans micromechanical retention, basedon the following principles:• The larger the surface to be bonded

the better.•

The surface energy of the bonding sub-strate must be much higherthan that ofthe adhesive in order to be able to com-pletely wet the substrate with the adhe-sive (intimate contact)

• The less the bonded interface isstressed (eg, by polymerization shrink-age or mechanical stress) the better itis for the bond.

Bonding to Tooth SubstratesFor enamel etching, hydrophosphoric acidis the etchant of choice. If the surface isdried perfectly, the hydrophobic acrylatesare able to wet it completely and create amicromechanical bond. Modern self-etch-ing primers for dentin may also create suf-ficient structural changes in enamel forbonding (Hannig M, et al, oral communi-cation, 2000).

I n dentin, the situation is more difficult.There are two things which must beaccomplished. First, one must be willing to

etch dentin with acids, in order to exposethe collagen network. Second, hydrophilicmonomers (primers) must be used to wetthe hydrophilic dentin and to prepare theway for the penetration of the more hy-drophobic bonding resins. This approachdemands a meticulous application of themethodological sequence, because onlythen is it possible to achieve the goal ofcomplete penetration. This technique isvery user sensitive because it is easy tomake errors, eg, the dryness or wetness ofdentin are crucial parameters that cannotbe standardized clinically. Today, multipur-pose or universal bonding agents arepromising because there is relatively limit-ed opportunity for error (Blunck U andRoulet JF, oral communication, 2000 ).21

Bonding to RestorativeMaterialsBonding to glass-based ceramics (felds-pathic and glass ceramics) follows thesame principles as does bonding to enam-el because etching with hydrofluoric aciddissolves the glass phase, thus exposingthe crystals and creating a microretentivesurface.' Silanization renders the etchedsurface hydrophobic, thus enabling the di-acrylates to wet it perfectly.23

165


Ceramics that do not contain a glassphase, eg, Al2O3- or zirconium oxide-basedceramics, may not be etched with hydro-fluoric acid. Surfaces of these ceramicsare roughened by sandblasting. Betterwettability may be achieved by applyingsilane, but only after the surface hasbeen silicatized by depositing an extreme-ly thin layer of silica on the surface bymeans of either a pyrolytic (Silicoater,Kulzer, Weilheim, Germany) ortri-bochem-ical (Rocatec, Espe, Seefeld, Germany)process. However, there are some indica-tions that bonds obtained by these meth-ods are not stable over longer periods,probably because of hydrolytic degrada-tion.12

The third alternative for bonding to ce-ramics is to use active monomers with theability to bond to surface metal oxides pre-sent in ceramics. A good example isPanavia-7 (Kuraray, Osaka, Japan), a resin-based luting agent containing 4 META.With this type of resin, excellent long-termtensile strength data have been reportedwith zirconium-based ceramics. 38

Bonding to composites is quite complexand still challenging. Modern compositesare highly filled materials that have fewdouble bonds for copolymerization, in par-ticular when they are used for indirectrestorations cured to a high degree of con-version. Assume that a resin is filled to 60%volume. This means that in a cross sectiononly 40% of the surface is left for copoly-merization. In this 40% of the surface, onecan assume that at least 60% of the dou-ble bonds are consumed. There-fore,chemical copolymerization is not very suc-cessful. An approach to increase the com-posite-composite bond is to roughen thesubstrate surface by sandblasting andthen increase the wettability by silanating

the silica-containing filler. With this tech-nology, 90 MPa fracture strength is ob-tainable, in contrast to the 170 MPastrength that is obtainable for unbondedbeams. 14 Another reliable technique is tosandblast the composite surface with a sil-ica-coated AI2O3 powder (Rocatec or Coe-Jet, Espe) prior to silanization.

Rationale for the IndirectApproachComposites shrink by approximately 3%(volume) upon polymerization, thus chal-lenging the adhesive bond. The forces de-veloped at the bonding interface dependon the configuration of the cavity and thespeed of the polymerization reaction 7 andmay exceed the adhesive forces, thus cre-ating debonding. The indirect approach isone solution to counter the polymerizationshrinkage of composites. With the bulk ofthe restoration being manufactured out-side the oral cavity, the absolute value ofthe polymerization shrinkage of the lutingcomposite only is very low and has only aminor effect on the interface. It is thereforepossible to place inlays with finishing linescervically in dentin, where the adhesion ofcomposites is inferior to that obtained inenamel.3

Composite Inlays and Onlays

Composite inlays and onlays can be con-structed using different techniques, in-cluding semidirect techniques (intraoraland extraoral) and indirect techniques.

The semidirecttechniques allow inlaytobe constructed at the chairside and lutedat the same appointment. Indirect tech-

1 66


niques involve laboratory collaborationand at least two clinical sessions.

The cavity is prepared according to thesame principles and using the same in-strumentation as that employed for ce-ramic inlays and onlays. The luting phaseis the same except for the management ofthe bonding surface.

Technique SelectionFour main clinical parameters have beendefined to facilitate the selection of themost appropriate restorative option3 :

•

Number of restorations•

Size of restorations•

Cavity geometry•

Location and anatomy of the teeth

Semidirect Intraoral Technique(Direct Composite Inlay)This technique is indicated for the restora-tion of one or a maximum of two teeth atany one time.

The inlay is formed by placing a fewcomposite increments into a tapered cavi-ty previously insulated with two coats of ani nsulating glycerin gel medium (Separator,Coltene, Altstatten, Switzerland). A base ofa conventional glass-ionomer cement isplaced to eliminate undercuts. It is recom-mended that using any resin-based mater-ial, such as resin-modified glass-ionomercement (RMGIC), compomer, or compos-ite, be avoided because, despite appropri-ate cavity insulation, the composite inlaymay adhere to the base, impeding removalof the inlay.

After in-mouth polymerization, the inlayis removed and the proximal anatomy, ifnecessary, is corrected and refined. Lastly,

following the heat and light treatment in aspecial oven (DI 500, Coltene), the restora-tion can be luted with composite resin ce-ment. The intraoral composite inlay is per-haps the most economical way of produc-ing luted restorations and undoubtedlypermits the provision of inlays of optimalaccuracy.22

The principal disadvantage of this pro-cedure is the difficulty encountered inremoving the inlayfrom the cavityfollowingl i ght curing. This necessitates careful caseselection. Intracoronal cavities of one ortwo surfaces with a regular, simple designare best indicated for this purpose.Cavities with three surfaces or with severalwalls are not ideal because the compositeresin tends to lock against the walls duringpolymerization, thereby hindering removal.Cuspal coverage should be avoided withthis technique because of the lack of theantagonist reference. Furthermore, cavitywalls must be free of undercuts, smooth,and characterized by a divergence of morethan 18°.36 This invariably requires a sacri-fice of sound occlusal tooth tissue.

The principal advantage of this tech-nique is the chairside production of a lutedrestoration without the need to take ani mpression.

Extraoral Composite Inlays(Indirect Chairside Inlays)Composite inlays and onlays can be pro-duced chairside with the involvement ofextraoral steps. This method is best suitedto the restoration of large intracoronal cav-i ties (Class I and II).

This technique relies on preparing thecomposite restoration on a silicon cast ob-tained from an impression. In contrast tothe intraoral technique, the walls of the

167


Fig 13-2 The first premolar is restored by means ofa direct composite filling. Following restoration re-moval, the second premolar and the molar are linedwith a flowable composite to complete cavity prepa-ration for chairside composite inlays.

Fig 13-1 Preoperative view of a maxillary quadrant.The restorations in the premolars and molar mustbe replaced because of recurrent caries and poormarginal adaptation. The first premolar will berestored by means of a direct composite restoration;the second premolar and the molar, because of theextent of the previous restorations, will be restoredusing a semidirect composite resin technique.

Fig 13-3 A silicon cast is prepared and the dyesare separated with a scalpel.

preparation should have a divergence ofonly 10°, allowing a more conservative ap-proach during cavity preparation (Figs13-1 and 13-2). The impression can berecorded using alginate, but a more accu-rate impression using silicon is preferable.A specially formulated, fast-setting vinylpolysiloxane (Mach-2 Die Silicone, Parkell,Farmingdale, NY) is injected into the im-pression following insulation with an insu-l ating spray (New Break Agent, ADM SRL,Muggio, Italy). In this way a working cast isobtained within a few minutes. Dyes canbe separated with a scalpel to obtain opti-

mal adaptation and contour of the restora-tions in the cervical region, together withappropriate proximal contacts (Fig 13-3).Small internal undercuts can be toleratedgiven the flexibility of the silicon cast.However, such undercuts must be re-moved from the fitting surface of therestoration prior to luting.

The restoration is completed with smallincrements of opaque and translucentcomposite (Figs 13-4 to 13-6) and luted inthe same appointment (Figs 13-7 to 13-9).I n the case of intracoronal restorations, theocclusal anatomy can be readily created.

1 68


Fig 13-4 A dentinal composite is applied to the

Fig 13-5 An increment of enamel composite isfloor of the preparation. An enamel composite is

placed occlusally.used to build up the proximal wall.

Fig 13-6 The two inlays after finishing and polish-

Fig 13-7 During the same appointment, the inlaysi ng.

are seated in the cavities for the try- in.

Fig 13-8 The restorations after luting,

Fig 13-9 The same quadrant 1 month later.

16 9


Fig 13-10 Preoperative view of a mandibular quad-rant. The two molars include extensive caries.

Fig 13-11 The cavities are prepared to receive acomposite base. Given the reduced thickness of theli ngual walls, these cusps should be reduced duringthe final stages of cavity preparation.

However, with this technique, the oppos-ing reference tooth is not available andcomplex restorations may only be built upwith reference of the adjacent teeth, result-i ng occasionally in the unavoidable needfor occlusal adjustment following luting.

I ndirect Inlays (Lab-MadeComposite Inlays)Abutting Class II cavities involving partialor full coverage cannot be properly re-stored using the above techniques.Attempts to use semidirect techniqueswould require a segmental procedure,leading to extended chairside time andsenseless clinical effort.

Therefore, indirect composite tech-niques are best suited for such cases, al-though they involve at least two clinicalsessions with provisional ization and thel aboratory construction of the restorations.The main advantage of the indirect tech-nique is the provision of restorations withoptimal occlusal anatomy, the restorationhaving been formed with reference to theopposing arch.

I ndirect composite inlays and onlayscan be constructed using conventionall ight-cured, small-particle hybrid materialsnormally used for direct restorations. Figs13-10 to 13-28 illustrate a case managedusing this technique.

Some new materials specifically devel-oped for crown and bridge work are alsoindicated for indirect restorations (eg,Belle-Glass, Kerr; Sculpture FibreKor,Jeneric/Pentron; Targis-Vectris, Ivoclar).These systems require special, expensivedevices for cure and postcure procedures.However, the manufacturers claim optimalmechanical and physical properties, to-gether with excellent surface stability.Different clinicians have demonstrated thatexcellent esthetic results can be achievedwith such materials2,6,17,26; however, todate little scientific data are available con-cerning the clinical behavior and longevityof restorations formed using these systems.

170


Fig 13-12 The completed preparations for twocomposite onlays. In such situations, only the indi-rect technique creates opportunity to achieve idealocclusal anatomy.

Fig 13-13 A conventional plaster cast is obtained

Fig 13-14 An initial layer of dentin-colored comfrom a silicon impression. The first step involves

posite is applied.placing wax as a spacer.

Fig 13-15

The lingual walls are built up with

Fig 13-16 The finished restorations.translucent composite.

1 7 1


Fig 13-17 The composite onlays after polishing.

Fig 13-18 The use of rubber dam is essential in ad-hesive procedures.

Fig 13-19 The composite onlays at the time of try-

Fig 13-20 The restorations should be luted sepa-in. rately using Teflon plumbing tape to protect the re-

stored tooth.

Fig 13-21 The luting cement is applied to the cav-

Fig 13-22 An ultrasonic tip is applied tothe restora-ity and the onlay is inserted and seated manually.

tion to ensure complete seating.

172


Fig 13-23 Cement excesses must be carefully re-

Fig 13-24 The flat exposed surfaces are finishedmoved before polymerization using a probe and

with abrasive disks.dentotape interproximally.

Fig 13-25 The cervical margin is finished using an

Fig 13-26

The final luster is obtained using pol-oscillating finishing tip.

ishing brushes.

Fig 13-27 The restorations after finishing and pol-

Fig 13-28 The same quadrant 1 week later.i shing.

17 3


Indirect CeramicRestorations-Step By Step

Prior to cavity preparation, a silicon im-pression of the quadrant to be restored istaken and set aside to be used in the man-ufacture of the temporary restoration. Thecavity preparation is similar to that of acomposite inlay. The general rule is theless complex the cavity shape the better.The preferred burs are the Cerinlay dia-monds (Intensiv, Grancia, Switzerland). Asshown in the case presented in Figs 13-29to 13-81, tooth buildup, if required, must becompleted prior to final preparation (Figs13-29 and 13-30). This can be achievedwith either a glass- ionomer cement (Fig13-31) or with composite and adhesivetechniques (Fig 13-32). During final cavitypreparation the clinician must allow for theminimal thickness of the restorative mater-ial (1.5 mm). If not done prior to cavitypreparation, undercuts (from caries or for-mer cavities) are filled with glass-ionomercement, resin-modified glass-ionomer, oradhesively placed composite. Bevels arenot prepared because the ceramic cannotbe cast or sintered into knife edges. Thinproximal enamel portions (Fig 13-33) areeliminated with either axial wall trimmers( LM 161/162 and LM 165/166, HU Friedy,Chicago, IL) (Fig 13-34) or very fine dia-monds (Comet No. 8889 314 010 andNo. 889EF 314 010, Brasseler, Lemgo,Germany) (Fig 13-35). Internal featuresshould be rounded to avoid stress con-centrations (Fig 13-36).

Before recording the working impres-sion it is important to expose the cervicalmargin, if it is located subgingivally, eitherby placing a retraction cord (Fig 13-37) orby undertaking a small papillectomy withan electrotome. The impression materials

of choice are the polyvinyl siloxanes, how-ever, it is important to know the limitationsof these materials. It is also important to beable to dry the cavity before taking the im-pression. Furthermore, it is to be remem-bered that these materials reach their fullyelastic properties only after 10 minutes. Ifthe correct procedure is followed, the den-tal technician may get a perfect, distortion-free impression (Fig 13-38), which may bemade into an accurate cast. A bite regis-tration is obtained using a stiff silicone, eg,Silagum AV-Quick-Bite (DMG, Hamburg,Germany).

For temporization, the silicon impres-sion obtained prior to the preparation ofthe teeth is trimmed back to the center ofthe adjacent teeth (Fig 13-39). It is thenfilled with a composite for provisionalrestorations, eg, Luxatemp Automix (DMG),and repositioned in the mouth (Fig 13-40).It is important to verify the repositioning ofthe impression to avoid provisionals thatare too high. The provisional inlay is re-moved during the elastic phase of thematerial (Fig 13-41) and subsequentlytrimmed with a scalpel blade, and if nec-essary with tungsten carbide burs. Theprovisional inlay is then cemented with aprovisional cement and adjusted occlusal-ly as necessary (Fig 13-42).

I t is beyond the scope of this publicationto explain in detail the laboratory proce-dures for the manufacture of ceramici nlays. Readers are referred to other publi-cations for the description of this technol-

ogy.3,30 However, some points of detail are

of particular importance. It is an advantageto provide the dental technician with asimple face-bow registration to ensurethat the casts are articulated accurately.Furthermore, the technician should obtaintwo casts from the impression. One is

174

I ndirect Ceramic Restorations-Step By Step

Fig 13-29 Amalgam restorations in teeth 14 and

Fig 13-30 The restorations are removed and the15 to be replaced given recurrent caries.

caries is excavated.

Fig 13-31 Reconstruction of tooth 15 using glass-

Fig 13-32 Tooth 14 is reconstructed using a com-i onomer cement.

posite core.

Fig 13-33 Appearance following cavity prepara-

Fig 13-34 The shape of the distolingual wall intion. Note the inappropriate configuration distobuc-

tooth 15 is adjusted using an axial wall trimmer.cally in tooth 15.

175


Fig 13-35 The enamel finishing line is given a butt-

Fig 13-36 The completed cavity preparations.j oint configuration using a fine diamond tip.

Fig 13-37

Retraction cord is placed to expose

Fig 13-38 The polyvinyl siloxane impression. Notethe cervical margins.

that the margins of the preparations are accuratelyrecorded.

Fig 13-39 The initial silicon impression is trimmedto facilitate reseating in the mouth.

176

Fig 13-40 The filled impression (Luxatemp) is repo-sitioned. Notethe opportunityto ensure accurate re-seating.


sectioned and used as a working cast. Theother is left unsectioned and used as afixed (control) cast. Delivery of the finishedrestorations should be on the unsectionedcontrol cast (Figs 13-43 to 13-45). At thecementing appointment, the provisionali nlay is removed (Fig 13-46) and rubberdam is applied. The cavity is thoroughlycleaned (Fig 13-47). An airborne particleabrasion instrument, using soluble phos-phates as an abrasive, is convenient forthis purpose. The inlay is then tried in andtested for fit and proximal contacts (Fig 13-48). Only then is the inner surface of the in-l ay conditioned for bonding. First, the inlayis degreased with an organic solvent (eg,acetone) (Fig 13-49). For the subsequentsteps it is a good practice to put the inlayon a support of boxing wax (Fig 13-50).The inner surface of the inlay is etched withhydrofluoric acid (eg, Cerec Etch, Vita,Sackingen Germany) (Fig 13-51) for 90seconds and thoroughly rinsed (Fig 13-52). To improve wettability with resins andsubsequently the bond strength, theetched surface is coated with a silane. 23,31

An alcohol-based MPS solution (5%),freshly activated with an alcoholic acetatesolution (5%) is preferred. The solvent canbe evaporated efficiently with a blast of hotair (hair dryer) for 30 seconds. This signifi-cantly increases the bond strength. 31

After protecting the adjacent teeth withmatrix bands, the enamel is etched for 30seconds (Fig 13-53) and the dentin (totaletch) for 15 seconds (Fig 13-54) using aphosphoric acid gel. This step is followedby careful rinsing (Fig 13-55). With thistechnique it is important not to excessive-ly desiccate the dentin; it should remainglossy (Fig 13-56). The bonding system isthen applied (Figs 13-57 and 13-58) but notcured. An alternative to this procedure is

the use of a universal bonding agent, ca-pable of etching enamel and dentin, prim-ing, and bonding. However, this technolo-gy is not yet fully investigated . For luting, adual-cure, high-viscosity luting composite(Sonocem, Espe) (Fig 13-59) is used inconjunction with ultrasonic energy (Fig 13-60).5,19,29 If it is decided not to use the ul-trasonic technique, then a low-viscosity,dual-cured luting composite should beused. Once the inlay has been fully seated( Fig 13-61), all excess composite materialmust be removed (Fig 13-62). Before anycomposite excess is removed proximallywith dental floss, the inlay must be held inits final position with a spatula or a ball-point explorer (Fig 13-63). Finally the mar-ginal area is covered with a glycerin gel(Airblock, Dentsply, Konstanz, Germany)( Fig 13-64) and the composite is carefullycured from all aspects (Figs 13-65 and 13-66). Occlusal adjustment is completedvery carefully with fine finishing/polishingdiamonds (Figs 13-67 to 13-71). Trimming,finishing, and polishing is commencedwith scalpel blades or scalers (Figs 13-72and 13-73) and then with ultrafine dia-monds (Comet No. 889EF 314 010,Brasseler) (Fig 13-74). Final polishing iscompleted using aluminum oxide-coatedfinishing/polishing disks (eg, Soflex, 3M,St. Paul, MN) (Figs 13-75 to 13-77) andstrips (eg, Epitex Composite FinishingStrips, GC Dental Products Corp, Kasugai,Aichi, Japan; SoflexStrips, 3M) (Figs 13-78to 13-79). Final surface gloss is obtainedwith silicanitrite-impregnated nylon brush-es (Occlubrush, Hawe Neos, Switzerland)( Fig 13-80). Because it is unavoidable to re-move some enamel during the polishingprocedures, the field is finally fluoridatedwith a fluoride gel (Fig 13-81).

177


Fig 13-41

The provisional inlays immediately fol-

Fig 13-42 Try-in of the provisional inlays.lowing removal. The excesses can easily betri mmed with a scalpel blade.

Fig 13-43 The ceramic inlays on the control

Fig 13-44 The ceramic inlays on the controlcast (occlusal view).

cast (palatal view).

Fig 13-45 The ceramic inlays.

Fig 13-46 The preparations following the removalof the provisional inlays.

1 78


Fig 13-47 After rubber dam placement, the cavi-

Fig 13-48 The inlays are tried in. Fit and proximalties are thoroughly cleaned.

contacts are checked.

Fig 13-49 The inlays are degreased with acetone.

Fig 13-50 The inlays are fixed on sticky wax.

Fig 13-51 The fitting surface is etched with hydro-

Fig 13-52 Careful rinsing.fluoric acid.

1 79


Fig 13-53 Etching of the enamel for 30 seconds.

Fig 13-54 Total etching.

Note the protection of the adjacent teeth with matrixbands.

Fig 13-55 Careful rinsing.

Fig 13-56 Gentle drying. The dentin must remainmoist (glistening).

Fig 13-57 Primer is applied.

Fig 13-58 Adhesive is applied.

180


Fig 13-59 The highly viscous luting composite is

Fig 13-60 The inlay is positioned with ultrasonici ntroduced into the cavity.

energy.

Fig 13-61 Complete seating is verified with an ex-

Fig 13-62 Excess composite material is removed.plorer.

Fig 13-63 The inlays are held in position with small

Fig 13-64 The margins are covered with glycerinballpoint instruments during proximal flossing.

gel.

1 81


Fig 13-65 Light curing from proximal aspect.

Fig 13-66 Light curing from occlusal aspect.

Fig 13-67 Occlusal adjustment. The inlays are in

Fig 13-68 Removal of occlusal interferences withhyperocclusion.

a fine diamond bur.

Fig 13-69 Correction of residual occlusal interfer-ence using an ultrafine diamond bur.

182

Indirect Ceramic Restorations-Step By Step

Fig 13-70 Centric occlusal contacts after correc-

Fig 13-71 Occlusal contacts in function (workingtion.

side).

Fig 13-72 Removal of excess composite fins with

Fig 13-73 Removal of excess composite fins withscaler.

scalpel blade.

Fig 13-74 Removal of excess composite fins withultrafine diamond tip.

1 83


Fig 13-75 Polishing of proximal

Fig 13-76

Polishing of occlusal surface withsurface with Soflex disk.

Soflex disk.

Fig 13-77

Polishing of proximal surface with

Fig 13-78 Soflex finishing stripsSoflex disk.

have an uncoated central sectionthat enables the dentist to insertthem through the contact pointwithout damaging the approximat-i ng surfaces.

1 84

Longevity of Indirect Posterior Restorations

Fig 13-79 Polishing the proximal-cervical area witha finishing strip.

Fig 13-80 High gloss is obtained with an Occlu-brush.

Fig 13-81

Fluoridation of the area with a gel.

Longevity of Indirect PosteriorRestorations

Esthetic posterior indirect restorations havebeen available for more than 15 years. Theyhave proven their clinical reliability in manycontrolled studies. The longevity of com-posite inlays is documented in the studiessummarized in Table 13-1. The low numberof reports exceeding 5 years of observationti me may be explained by the rate ofdevelopment of new composite materials.

Ceramic inlays are better documented.Studies with observation times of up to 10years are listed in Table 13-2. Annual failurerates for ceramic inlays range from 0% to4%. The mean annual failure rate for the re-ported studies (observation times between5 and 10 years) is 1.2%. However, the widedifferences in clinical success and failurerates indicate that the procedures are tech-nique sensitive. Good results seem to re-quire extremely careful and skilled com-pletion of the restorations.

1 85


Table 13-1 Longevity of composite inlays and onlays

Table 13-2 Longevity of ceramic inlays in studies with observation times > 5 years

'Two inlays were fractured in this study.

1 86

Conclusions

Conclusions

Esthetic indirect restorations have proven tobe a good solution if large cavities are to berestored or if there is more than one restora-tion required per quadrant. Under such cir-cumstances the indirect approach is less

ti me consuming and more controllable thanalternative techniques. However, to providei nlays and onlays it is generally necessarytosacrifice more sound tooth tissue than isnecessary with direct techniques to createthe necessary path of insertion.

1 87


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28. RouletJ-F. Longevity of glass ceramic inlays andamalgam-Results up to 6 years. Clin OralI nvestig 1997;1:40-46.

29. Roulet J-F, Eidenbenz S, Zollner W, Gasser O,Ellrich K. The use of composite restoration ma-terials for the luting of inlays, onlays, veneersand similar restorations by means of high fre-quency vibration, i n accordance withPublication No. DE 40 32 505/A1. Germanpatent EP/0480472/B1. 12 Oct 1990.

32. Sjogren G, Molin M, Van Dijken JWV. A 5-yearclinical evaluation of ceramic inlays (Cerec) ce-mented with a dual cured or chemically curedresin composite luting agent. Acta OdontolScand 1998;56:263-267.

33. van Dijken JW. 5-6 year evaluation of direct com-posite inlays [abstract 1801 ]. J Dent Res 1994;73:327.

34. van Dijken JW, Hoglund-Aberg C, Olofsson AL.Fired ceramic inlays: A 6-year follow up. J Dent1998;26:219-225.

35. Walther W, Reiss B, Toutenburg H. Longi-tudinale Ereignisanalyse von Cerec-Einlageful-lungen. Dtsch Zahnarztl Z 1994;49:914-917.

36. Wassell RW, Walls AW, McCabe JF. Cavityconvergence angles for direct composite inlays.J Dent 1992;20:294-297.

37. Wassell RW, Walls AW, Van Vogt-Crothers AJR,McCabe JF. Direct composite inlays versus con-ventional composite restorations: Five year follow-up [abstract 2254]. J Dent Res 1998;77:913.

38. Wegner SM, Kern M. Long-term resin bondstrength to Zirconia ceramic. J Adhes Dent2000;2:139-147.

30. Roulet J-F, Herder S. Bonded Ceramic Inlays.Chicago: Quintessence, 1991.

31. Roulet J-F, Sdderholm KJ, Longmate J. Effectsof treatment and storage conditions on ceram-i c-composite bond strength. J Dent Res 1995;74:381-387.

39. Wiedmer CS, Krejci I, Lutz F. Klinische, rontge-nologische and rasterelektronenoptische Unter-suchung von Kompositinlays nach funfjahrigerFunktionszeit. Acta Med Dent Helv 1997;2:301-307.

189

Chapter 14

Bonded Partial Restorations forEndodontically Treated Teeth

Jean-Jacques Lasfargues, Frederic Bukiet, Gil Tirlet, andFrank Decup

I ntroduction

The endodontically treated tooth has beenthe subject of numerous publications,both in the field of biomechanics and mostcommonly in relation to prosthetic den-tistry. In a clinical research project con-ducted over a period of 25 years and in-volving a sample of 1200 endodonticallytreated teeth, Sorensen and Martinoff 35demonstrated the reliability of full crownsfor the restoration of pulpless teeth.Notwithstanding their findings, Sorensenand Martinoff concluded that the preser-vation of dental structures was the key-stone forsuccessful restorations. 34 I ndeed,the loss of dental tissue is presently con-sidered to be the most significant factor in-fluencing problems in the reconstructionof endodontically treated teeth. 4,15

A high prevalence of caries, togetherwith interventive iatrogenictreatment, havehad a global effect on the unnecessaryloss of tooth tissues. This has made therecourse to post and cores and full cover-age crowns an everyday event in clinicalpractice (Figs 14-1 a to 14-1 c). Trends to-ward less invasive forms of restorative den-

tistry, 6,16,17,38 together with ongoing prog-ress in adhesive dentistry, 12,41 have crea-ted new opportunities forthe restoration ofendodontically treated teeth.

The volume of tissue loss due to caries,trauma, erosion, abrasion, attrition, oriatrogenic operative intervention remainsthe determining factor in planning therestoration of endodontically treated teeth.However, the location and configuration ofthe endodontic access has been consid-ered to be as important as the volume ofthe lost tissue.25,31-33,42 Compared withother clinical factors such as existingrestorations and previous treatment, tissueloss and the nature and form of the en-dodontic access will tend to determinetreatment, whether prosthetic or other-wise.

This chapter deals with the advantagesand indications of bonded partial restora-tions (BPRs) in the restoration of en-dodontically treated teeth. BPRs includerestorations requiring limited removal oftooth structure, relative to that requiredfor a crown or post and core approach,and those that gain resin retention frombeing bonded.

1 91

Bonded Partial Restorations for Endodontically Treated Teeth

Figs 14-1a to 14-1c Posts do not reinforce endodontically treated teeth , but are indicated when toothstructure is insufficient to retain a core and crown.

Fig 14-1a Postoperative view of an endodontic re-treatment with cast post and core.

Fig 14-1b Clinical view of a cast, semiprecious al-l oy core luted with glass-ionomer cement (GC FujiPlus).

Fig 14-1c Full-coverage metal-ceramic crown.

Fig 14-2 A root fracture of an endodontically treat-ed tooth induced by iatrogenic restorative interven-tion. The maxillary premolar was restored with a castpost and core prior to being used as a fixed partialdenture abutment.

1 9 2

General Advantages of Bonded Partial Restorations

Problems with EndodonticallyTreated Teeth

I n many papers dealing with endodonti-cally treated teeth, post and core restora-tions are the recommended treatmentoption20,29,30 based on the view that allendodontically treated teeth should becrowned. As reported by Sabek,28 i t there-fore is not surprising that the majority ofpractitioners consider most endodontical-ly treated teeth to require a post and coreand crown. Concurrently the endodonti-cally treated tooth is generally consideredto be fragile and at risk of fracture.I rrespective of the fragility of the remainingtooth tissue, it is suggested that BPRs of-fer advantages over posts and cores andcrowns, including the preservation of den-tal tissues and the strengthening of thetooth through bonding. BPRs should,however, be considered as an alternativerather than as a substitute for post andcrown restorations.

General Advantages of BondedPartial Restorations

When considering the reconstitution of anendodontically treated tooth, it is wise tothink both in terms of restoration resis-tance and the durability and function of therestored tooth unit. The key issue is to de-termine the method of restoration that willoffer the best opportunity to preserve thetooth in the dental arch during the patient'sl ifetime with the safest and leastdestructive form of intervention.

Dental tissues do not regenerate.Choosing the most conservative solutionis therefore essential to stop the "dentalapoptosis cycle." 16 The inevitable demise

of this cycle, ie, the loss of the tooth, shouldbe avoided. Therefore alternatives tocrowns that do not involve the placementof a post should always be favored. 14

Prefabricated metallic screw and castposts are often associated with radicularfractures. 4 They cause unnecessary fail-uresthat in most cases are untreatable (Fig14-2). Once considered as a means of re-i nforcing roots, a post is now considered tohave a major weakening effect on theremaining tooth tissue. 10,29,40 I n posteriorteeth, posts are dangerous at certain rootlevels; moreover, they are contraindicatedfor many short, curved, and ribbon-shapedroot canals (Figs 14-3a to 14-3e).

There are important differences be-tween the volumes of coronal and radicu-lar dentin in anterior as opposed toposteriorteeth. 29 I n anterior teeth the coro-nal dentin is relatively thin and of lowvolume compared to the relatively thick,high volume of the radicular dentin. In pos-terior teeth this relationship is reversed,making the use of posts in posterior teethall the more hazardous.

Because posteriorteeth function mainlyi n compression, the benefit of a post is lim-ited. When using a BPR that involves anadhesive interface over a large surfacearea, the placement of a post for retentionis unnecessary, especially if the residualtissues are maximally exploited for bond-ing. This situation is increasingly commonin clinical practice.

I n anteriorteeth and bicuspids, the needfor a post and core is more often the rule.However, in such situations a much-debat-ed alternative is the use of a bonded non-metallic post and core. Examples of suchsystems are based on zircon or carbonfiber posts. 36

193


Figs 14-3a to 14-3e An endodontically treated molar requiring a full-coverage crown. A post is not indi-cated if a moderate amount of coronal tissue remains. In contrast, a direct partial-bonded core is recom-mended.

Fig 14-3b Rubber dam isolation and access to

Fig 14-3c After dentinal conditioning with polythe pulpal chamber.

acrylic acid (GC Dentin Conditioner), resin-modifiedglass ionomer (GC Fuji IILC) is injected into the pul-pal chamber.

Fig 14-3d The completed core restoration (Tetric,

Fig 14-3e The all-ceramic crown (In-ceram).Vivadent) following bonding and microhybrid com-posite layering.

1 94

Fig 14-3a Immediate postendodontic view of thefirst mandibular molar.

Biomechanic Advantages of Bonded Partial Restorations

New root canal preparation techniques 5and means to assess the prognosis ofendodontic treatments 26 are of additionalassistance in treatment planning. Sealingof the root filling prior to restoration of thecrown is a critical determinant in ensuringa favorable prognosis. 3° Recent data indi-cate that failures classified as endodonticfailures are, in manycases,aconsequenceof bacterial microleakage due to a failureto seal the root canal filling prior to pros-thetic treatment.24 Leakage of a temporarycrown and exposure to saliva duringpreparation of the post space and at thetime of impressions, notwithstanding sub-sequent leakage at the margins of the finalcrown, are well-known causes of failure.Consequently, it is preferable, wheneverpossible, to avoid the placement of a postthat requires the partial removal of the rootfilling. For the same reason, it is necessaryto effectively restore a tooth immediatelyfollowing endodontic treatment, even incases with preexisting apical periodontitis( Figs 14-4a to 14-4e). If the permanentprosthetic solution must be delayed, atransitional BPR will provide a better sealthan a temporary crown.

I n the event of recurrent infection, re-treatment may be carried out more easilywhen a provisional rather than a per-manent restoration has been placed. Suchrestorations facilitate the placement of rub-ber dam and provide a four-walled accesscavity that helps contain root canal irriga-tion solutions. In contrast, the presence ofa post and core crown greatly complicatesretreatment with the added risks of weak-ening, perforation, and fracture. 19

I n the case of immature teeth, BPRs arenecessary during apexification treatmentand in the management of the sequellae oftrauma. After gutta-percha obturation, a

BPR helps compensate for the weakeningof the residual radicular walls, and therebyhelps overcome some of the problemsassociated with the interruption of thedevelopment of the root.

The choice of a partial rather than afull-coverage restoration promotes peri-odontal health by leaving cervical emer-gence axial profiles unchanged andplacing the restoration margins supragin-givally. 14 Furthermore, in situations wherethe gingivae are thin or lack adequatewidth of attachment, the provision of par-tial rather than full-coverage crowns maypreclude the need for preprostheticmucogingival surgery. 1 °

A further advantage of partial crownrestorations is their cost relative to that offull-coverage crowns.

Biomechanic Advantagesof Bonded Partial Restorations

Data on the fracture resistance of vital andnonvital teeth are confusing, given thatthe results and conclusions of the availablestudies vary according to the methodsused.

In numerous studies the mechanicalproperties of dentin in vital and nonvitalteeth have been found to be similar. 13,25,31

However, nonvital teeth tend to be regard-ed bythe majority of practitioners as weak-ened relative to vital teeth. The most im-portant factor on which authors agreeis the weakening effect of the loss of toothstructure. 25,31-33,42 The clinician should,therefore, take account of various aspectsof remaining dental structures, namely:

• The number and thickness of the re-maining walls.

195


Figs 14-4a to 14-4e To prevent coronal leakage, a bonded restoration should be placed immediately fol-lowing successful completion of root canal treatment.

Fig 14-4a Upon completing the root filling, rubberdam is left in place. The pulpal chamber is cleanedof excess endodontic materials and the dentinalwalls of the access cavity are etched with phos-ohoric acid.

Fig 14-4b Sealing is performed using an appro-priate adhesive system (Optibond Solo, Kerr).

Fig 14-4c The pulpal floor is covered with a flow-able composite (Revolution, Kerr).

Fig 14-4d The first increment of posterior com-posite (Prodigy Condensable, Kerr) is placed usinga layering technique.

Fig 14-4e The final restoration.

196

I ndications for Bonded Partial Restorations

The nature of tooth tissue loss, with theloss of marginal ridges being an unfa-vorable factor.The morphology of the defect. Internalangles generate corner effects andmay be difficult to eliminate.

All operative procedures generate asignificant amount of stress in remainingtooth tissues. Procedures including en-dodontic treatment and cavity preparationmay induce cracks in the hard dental tis-sues. Such cracks may remain unnoticedbut may subsequently lead to fractures.To prevent cracks and cracked toothsyndrome, it is necessary to select a ther-apeutic solution that favors the reinforce-ment of the remaining dental structuresand allows the absorption of mechanicalstresses. Bonded restorations meet theserequirements.

Many studies have focused on the issueof the reinforcing effect of bonding, butresults differ from one author to another,mostly in relation to the type of restoration:

Ceramic inlays?Resin composite inlays 18Bonded metallic inlays 9Direct composite fillings1,2Bonded amalgams 23

It is important to note that all of thesestudies were laboratory based, typicallyusing intact premolars extracted for ortho-dontic reasons. The possibilities to rein-force structures clinically may, however, bel i mited because problems in vivo tend tofocus on endodontically treated teeth.However, data obtained by Ausiello et al 1,2

in two studies on endodontically treatedteeth give promising results.

The purpose of the first study2 wasto determine the fracture resistance of en-dodontically treated premolars, restoredwith bonded MOD restorations.The resultsshowed that the restored teeth had similarresistance to fracture as did intact controlteeth. In contrast, the resistance to fractureof teeth restored with either bonded amal-gam or a sandwich restoration, including a2- to 3-mm thick dentinal substitute (aglass-ionomer cement-composite sand-wich or a polyacid modified resin-com-posite sandwich), was inferior to that ofi ntact teeth, but greater than that ofendodontically treated teeth with an unre-stored mesio-occlusodistal cavity.

I n their second study, also involvingendodontically treated teeth, Ausiello et allshowed that under loading, bonded amal-gam and sandwich restorations sufferedsignificantly more degradation than didcomposite restorations through separa-tion of the interfaces.

However, no clinical study is known tohave confirmed these laboratory data. Thelong-term clinical benefits of bonding en-dodontically treated teeth must remainspeculative, in the absence of furtherscientific evidence. Prospective clinicalstudies are required to test the clinical per-formance of BPRs, relative to traditionalrestorations requiring substantially moretissue loss.

I ndications for Bonded PartialRestorations

The decision to select a conservativesolution to a problem, which would nor-mally be an indication for a crown, must bebased on considerations arising from clin-ical and radiographic examinations.

197


Besides the loss of tooth structure,which is the most significant local factor,general factors must also be considered.These include the patient's age, the prog-nosis of the endodonticallytreated tooth, 22and occlusal function (Table 14-1).

To simplify the quantitative and qualita-tive assessment of the loss of tooth struc-ture, reference will be made to the classifi-cation proposed by Mount and Hume 21and subsequently modified by Lasfargues

198

et al. 17 Although this classification, theSISTA concept, is based solely on the lossof dental structures without any referenceto pulpal vitality, it allows the loss of toothstructure in endodontically treated teeth tobe categorized according to the location ofthe lesion (site) and the extent (stage) ofthe lesion (Table 14-2). In this way, an oc-clusoproximal loss of tooth structure maybe qualified in the following ways.

Operative Procedures

•

SISTA 2.2: a lesion involving only oneproximal surface

•

SISTA 2.3 or 2.4: a mesio-occlusodistallesion in which one or morecusps have been lost

Stages 0 and 1 do not relate to en-dodonticallytreated teeth. Stage 2 is most-ly found in traumatized anterior teeth inwhich the loss of tooth structure is causedprincipally by the access cavity to theroot canal system. The most frequentlyencountered situations are the loss of hardtissues found in stages 3 and 4 associatedwith sites 1 and 2. In these situations, theextent of tissue loss must be considered interms of buccolingual width and depth. Al arge, thick residual enamel margin is a fa-vorable criterion for a BPR.8 I n other cas-es, a composite/metallic onlay with a met-al finishing line should be considered asan alternative. 39

Direct BPRs may be considered an op-tion for endodontically treated anteriorteeth classified as stage 3. BPRs are most-ly indicated when both marginal ridges arei ntact and the buccal wall is reasonablythick (SISTA 1.2 and SISTA 1.3).

I n stage 4 cases, a full-coverage crownwill generally be found to be the mostsuitable option. However, extension of thepreparation lingually for ceramic or com-posite veneers may be considered in themanagement of a fractured incisal edgein incisor teeth. The endodontic accesscavity may be filled using a direct tech-nique or incorporated in the design of thepreparation to increase retention and thestability of the veneer.

Posterior TeethA direct restoration of a heavily filled mi-crohybrid composite may be considered inposterior teeth in the following situations.


Different procedures may be considered,depending on the type of tooth and theextent of the loss of tooth tissue.

Defect (up to stage 3) present in site 1with the occlusion allowing retention bymeans of the weakened walls.Defect (up to stage 2) present in site 2with the loss of tooth structure involvingonly one of the two marginal ridges.

Anterior TeethI n general, BPRs are an option for the treat-ment of traumatized anteriorteeth; more in-vasive solutions are a last resort. Accordingto many authors, 14,20,27,32,33 a direct com-posite restoration is the preferred option forthe management of endodontically treatedanterior teeth with moderate loss of toothtissue, including an endodontic accesscavity (Figs 14-5a to 14-5h). In such situa-tions, it remains to be shown that the use ofa ceramic post is a valid option. 36

For a mesio-occlusodistal defect, indi-rect restorations are necessary.

I n order to facilitate endodontic retreat-ment, the canal orifices and pulpal cham-ber should be filled with a resin-modifiedlight-cured glass-ionomer cement. Theplacement of a flowable composite 3 as adentinal substitute may also be consid-ered to contribute to the distribution ofocclusal loads transmitted by the overlyingcomposite restoration and to limit the con-sequences of polymerization shrinkage. 37

199


Figs 14-5a to 14-5h Esthetic bonded partial restoration of an anterior tooth combining bleaching and adirect adhesive technique in a young patient.

Fig 145a Preoperative view. Despite successfulapexification, post core and crown restoration of thistraumatized incisor is contraindicated.

Fig 145c The esthetic improvement followingexternal home bleaching (Opalescence, Ultradent,South Jordan, UT).

Fig 145b The unsightly facial aspect of the dis-colored incisor, including an incisal composite.

Fig 145d With the composite restoration re-moved, the opening to the root canal is sealed witha light-cured glass-ionomer cement. The increasedoverjet with no intercuspation position contact is afavorable situation for a direct restoration.

200


Fig 14-5e In profile, the unfavorable buccal posi-tioning of the incisor is apparent. The contraindica-

tions for veneer or crown placement may be appar-ent.

Fig 14-5f Rubber dam placement, etching, andthe placement of matrix strips to protect the adja-cent teeth.

Fig 14-5g Incremental layering using saturateddentinal shades and translucent incisor enamelcomposite (Silux Plus, 3M, St. Paul, MN).

Fig 14-5h The final esthetic result.

201


Figs 14-6a to 14-6f Restoration of a first maxillary molar using an adhesive semidirect technique.

Fig 14-6a The restoration is built up directly inthe cavity following the application of a separator(Coltene, Altstatten, Switzerland).

Fig 14-6b Following polymerization, the onlay canbe removed. A tapered cavity preparation, free ofundercuts and finished with fine diamond burs, isnecessary to avoid locking in of the restoration.

Fig 14-6c Adjustment of the proximal contact, oc-clusal relationships, and morphological features.

Fig 14-6d The finished onlay is postcured by pho-tothermal treatment to improve hardness and wearresistance.

20 2


Fig 14-6e Rubber dam is placed prior to cemen-tation. The occlusal view shows the flat pulpal floorof glass ionomer and the tapered cavity design.

Fig 146f The restoration is cemented adhesively.

However, the use of materials of different

composition and construction may dimin-

i sh internal cohesion within the restoration

and thereby compromise the mechanical

resistance of the restored tooth unit.

I n case of extensive tooth tissue loss, a

semidirect or indirect restoration is the

preferable option. Such restorations are

strongly recommended for SISTA 2.3 situ-

ations and are considered essential for

SISTA 2.4 cases (Figs 14-6 to 14-8).

Partial and full cuspal coverage restora-

tions may be indicated for mechanical

resistance and for occlusal and esthetic

reasons.11 Many authors agree on the

need for cuspal coverage in such clinical

situations. 27,33 This solution can restore

the strength of the restored tooth unit.

Wiskott42 suggests that a mesio-occluso-

distal cavity in an endodontically treated

posterior tooth is sufficient indication for

the placement of a full crown. For this au-

thor, mechanical considerations prevail

over biological constraints. This is in con-

flict with the results of the study by Ausiello

et al . 2 I n the future, clinical studies should

focus on questions that influence treat-

ment decisions. In the meantime, evalua-

tions of clinical parameters will continue to

dictate the placement of either a BPR or a

crown.

203


Figs 14-7a to 14-7f Restoration of a first maxillary molar with a partial coverage bonded onlay using thei ndirect adhesive technique.

Fig 14-7a Preoperative appearance following re-moval of the intracoronal amalgam and endodonticretreatment.

Fig 14-7b The loss of tooth substance is classifiedSISTA 2.4. Rubber dam isolation is essential to pre-vent root canal contamination.

Fig 14-7c Tapered intracoronal design, enamelcoverage, butt joint finishing along the cervical mar-gin, and a flat pulpal floor (restored with flowablecomposite) are the main features of preparations forbonded composite onlays.

Fig 14-7d The laboratory-made onlay (Tetric lab-oratory composite and variolink adhesive system,Vivadent, Schaan, Liechtenstein) immediately afterbonding.

204


Fig 147e The clinical result afterthe replacementof the lingual amalgam with a direct composite.

Fig 14-7f Postoperative view illustrating the con-cept of the endododontic continuum, including theroot filling and the coronal restoration aimed at pre-venting root canal treatment failures.

Figs 148a to 14-8f Bonded partial restoration of a second maxillary molar using a metal-composite inlay.

Fig 148a Preoperative occlusal view. The loss oftooth substance is classified SISTA 2.3 with threeremaining walls (buccal, lingual, and distal). A met-al-composite mesio-occlusal inlay is indicated.

Fig 14-8b After endodontic retreatment.

205


Fig 14-8c After preparation. Full crown preparationis not indicated because the remaining tooth struc-ture extends beyond the buccal plane of the dentalarch.

Fig 14-8e The composite-metallic inlay on thel aboratory model. In cases in which cervical enam-el has been lost, a cervical metal finishing line helpsprevent recurrent caries.

Fig 14-8d As seen in the laboratory model, resis-tance form is afforded by the remaining wall beingreinforced by bonded composite (as a dentinalsubstitute) and the short cervical bevel.

Fig 14-8f After cementation with a glass-ionomerl uting cement (Ketac conditioner and Ketac Cem,Espe, Seefeld, Germany). The functional and es-thetic integration of the onlay is apparent.

206

Conclusion

Conclusion

Existing literature indicates that the lossof tooth structure rather than the lossof the pulp causes weakening of devital-ized teeth. Therefore, it appears desirableto favor more conservative solutions toproblems necessitating the strengtheningof damaged teeth. BPRs are an interestingoption in such situations. However, in lightof current knowledge, the use of BPRs

cannot be recommended for the restora-tion of all endodontically treated teeth. Inplanning the restoration of endodonticallytreated teeth, the advantages and limita-tions of the treatment options must beconsidered when formulating a manage-ment strategy. The fixed view that all en-dodontically treated teeth must be re-stored with a full crown has no scientificbase and should therefore be reviewed.

207


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37. Tassery H, Dejou J, Koubi G, Brouillet JL. Lesrestaurations composites posterieures directes.Choix du substitut dentinaire. Inf Dent 1998;6:365-370.

38. Tirlet G. Les bridges colles en composite fibre:applications au secteur posterieur. Real Clin1999;2:285-304.

39. Touati B, Pissis P. The compo metal inlay-onlay:unit restoration and methods of anchoringbridges. Actual Odontostomatol 1986;40:453-484.

31. Sedgley CM, Messer HH. Are endodonticallytreated teeth more brittle? J Endod 1992;18:332-335.

40. Valentin

C,

Levy G. The

radicular post.Specifications [in French]. Real Clin 1990;1:197-208.

32. Sivers JE, Johnson WT. Restoration of en-dodontically treated teeth. Dent Clin North Am1992;36:631-650.

41. Van Meerbeek B. Facteurs cliniques influen-gant la reussite de I'adhesion a I' email et a ladentine. Real Clin 1999;2:175-195.

33. Smith CT, Schuman N. Restoration of en-dodontically treated teeth: A guide for therestorative dentist. Quintessence Int 1997;28:457-462.

42. Wiskott HWA. Elements de biomecanique. CahProthese 1996;96:14-23.

34. Sorensen JA. Preservation of tooth structure:The key to the successful restoration. J ClinDent 1989;1: 39-40.

209

Chapter 15

The Oral and Dental Effects of Aging

Angus W.G. Walls and Michael Noack

I ntroduction

What do we mean by the term old? Peoplerarely accept that they are old, preferringto think that there is always someone whois a bit more frail, with a few more grey hairs(or fewer hairs) than they have. A reason-able estimate from most people is that theelderly are about 15 to 20 years older thanthe person you ask. The stereotype of anolder person as one with limited mobility,l imited access to care and consequentlyhigh levels of dependence is false. Thevast majority of older people live freelywithin their communities and have highlevels of motivation and self-esteem. Eventhose who are relatively frail make greatefforts to try to maintain as much inde-pendence as they can. Indeed, the loss ofindependence is one of the key variablesleading to social decline in an older popu-lation. For this reason, little things such ashaving a lock on your door so that you canshut people out and having your ownspace are important, particularly if you livein a nursing home or with your children.

Older people are an important popula-tion group because in virtually all westerncountries there is a greater percentage ofthe population surviving into old age. For

example, it is estimated that at the presenttime 8.44 million people in the UK areaged 65 and above (15.1 % of the popula-tion). This is projected to increase to 9.78million bythe year 2020 (17.4% of the pop-ulation).68 I n some countries, the impact ofthis increased longevity are compoundedby a falling birth rate so that there are rela-tively few young people developing to as-sist with and support their aging relatives.Good examples of this problem are foundin China and Italy. These factors combineto result in a change in the structure of ourpopulation, which at one time was broad-ly pyramidal with large numbers of youngpeople and a smaller elderly group. Thestructure is now more rectangular, withsi milar numbers of people in age groupsup to the age of about 65 years old.Thereafter, the size of the groups begins todecline as the most common causes ofmortality, which are associated with in-creasing age, begin to have an effect.These include cardiovascular disease,stroke, and cancer (Fig 15-1). 63

The oral health of older people is alsochanging contemporaneously. Edentu-l ism was a common feature of old age30 to 40 years ago. This is no longer thecase as increasing numbers of elderly

211


Fig 15-1 Population projections for the developed world. The solid bars represent the size of their respec-tive age groups in 1998. The line is the outline of the structure in 2050. 63

Fig 15-2 Proportion of the population of the UK that is edentulous by age group. 23

21 2

Aging

Fig 15-3 Projections for the fall in edentulousness over the next 50 years in the UK . 2 3

people retain some or all of their naturalteeth. This change is also occurring allover Europe, but has probably been bestdocumented in the UK as a result of thedecennial program of assessments ofadult oral health (Fig 15-2). Populationprojections based on these data for theUK continue to show a decline in rates ofedentulousness to levels of 8% for 65- to74-year-olds in 2028 compared with 74%50 years previously. The comparable fig-ures for those older than 75 years are 18%compared with 87%. This reduction inedentulousness will have a profound im-pact on the oral health care needs and dis-ease susceptibility of this age group, withan associated change in the patterns of oralhealth care that they require (Fig 15-3). 23

Aging

I ncreasing age has an inevitable, intrinsic,and irreversible effect on all tissues of thebody that are also evident in changesto the oral and facial tissues.

Oral Soft Tissues andSalivary GlandsAging effects in these areas includechanges in the submucosa, such as alter-ation in collagen structure and turnover, re-duced elasticity of elastin, reduction inmasticatory muscle bulk 40,41 and pro-found reductions in the numbers of secre-tory units in salivary glands. 48 Despite themarked histological changes in salivarygland structure seen in elderly people,there is little effect on salivary flow ratesfrom the major salivary glands in thispopulation group (Fig 15-4). 4,5,36 This isthought to be caused by a combination ofadaptive capacity on the part of the glandand increased vagal neurological tone,which increases secretory activity and isoften found in elderly people. Neverthe-less, the salivary secretory reserve is per-ceived to be lower i n elderly people.Hence, any challenges to salivary compe-tence, including gland destruction by dis-ease, radiotherapy, or the side effects ofdrugs55,64 will be more likely to producexerostomia in this age group. There are

21 3


Fig 15-4 Schematic diagram illustrating the changes in salivary secretory capacity compared with theneed for saliva to maintain health. The reserve (the difference between capacity and need) is much reducedin elderly people . 4

Fig 15-5 Projections for the proportion of the UK population with 20 or more natural teeth . 23

Oral Health Status of Elderly People

also some suggestions in the literature thatminor salivary gland function is diminishedwith age. 12,53

There is an impression that the oralmucosa becomes thinned and more frag-ile with increasing age, but there are fewdata to support this. One report concern-ing the lateral borderofthetongueshowedreduced epithelial thickness and a reduc-tion in the complexity of the rete pegapparatus. 51 These alterations mirror theprofound changes seen in skin with the ep-ithelial atrophy, increase in carbohydratecontent, and keratinization that occur withage.51,52 Oral manifestations may also re-sult from systemic age-related diseases,eg, atherosclerosis, which is more com-mon in elderly people than in other agegroups and may produce oral changes bya diminution in the blood supply leading tomucosal atrophy. 5o

TasteThere is an ongoing debate concerningthe effects of age on taste perception,particularly because change in taste per-ception may be associated with variationsin nutrient intake. 8 The changes in olfac-tory senses associated with aging are welldocumented,8 as are the associations be-tween smell and taste. The reported rela-tionships between aging and taste vary inboth the taste qualities (sweet, salt, sour,and bitter) involved and whether thei ntensity of the taste is heightened or less-ened.65 Nevertheless, there are associa-tions between increasing age and an in-crease in the threshold for detection ofsweet34 and salt. 3,15.60 I n addition, there issome evidence for greater confusion be-tween salt and sour in older subjects. 59

The quantity and quality of saliva affecttaste. While there are no reported alter-ations in salivary flow levels associatedwith age, there are changes in both the ion-ic and mucin composition of saliva. It maybe that these alterations influence the per-ceived flavor of food.

Oral Health Status ofElderly People

The DentateAmong the dentate, there is a reductionin the number of teeth present and in thenumber of functional pairs of opposingteeth, both anterior and posterior, associ-ated with increasing age. One measure ofa functional dentition that has been sug-gested is the proportion of people whohave 20 or more natural teeth. This is oneof the World Health Organization's oralhealth targets. 66 Currently, the averagedentate person older than 65 years in theUK has about 15 teeth, while about 29%have 21 or more teeth. In people olderthan85 years, these figures fall to an average of10 teeth per person, with only 5% having21 or more teeth. However, the proportionof people with 21 or more teeth is also like-ly to rise over the next 20 years in associa-tion with the projected improvements inoral health status (Fig 15-5).

Nevertheless, elderly people will stillhave fewerteeth than the young and will bemore likely to be reliant on a prosthesisof some sort for function. About 26% ofdentate subjects older than 65 years haveno teeth in one dental arch, ie, a completedenture in one jaw is opposed by naturalteeth in the other. This pattern of dentalhealth can be particularly limiting becausethe relatively high functional forces that

21 5


can be applied to the complete denture bythe opposing teeth often impair the stabil-ity of the denture.57

CariesRecent data have confirmed that cariesis the most important reason for toothloss in an aging population. 42 Also, thereis more untreated decay in elderly peopleon a population basis. 43,57 This is particu-larly apparent with trends in root caries,which increases with age and is moreprevalent in men, in people from lower so-cioeconomic groups, and in those who arehabitual nonattenders. 11 The crowns ofteeth are susceptible to decay throughoutthe life of the tooth. Conversely, the roots ofteeth become exposed with increasing fre-quency in elderly patients because of gin-gival recession caused by periodontal dis-ease. This results in new surfaces beingexposed and therefore becoming suscep-tible to decay in elderly patients.

The current group of dentate elderlypeople belong to a generation that has hadvarying extents of restorative dental care inyouth. The legacy of this is a large numberof retained heavily filled teeth. Conse-quently, it is difficult to assess caries activi-ty in the crowns of teeth because it tends totake the form of recurrent and secondarycaries in relation to existing restorations.The limited data available on caries incrowns of teeth in elderly subjects sug-gests an increasing frequency of carieswith increasing age. 2,19,57,67 This apparentincrease in caries activity may be due toincreasing disease activity or to reduceddental attendance resulting in more cariessurfaces being apparent during epidemio-logical studies of oral health for this agegroup.

Conversely, root caries has been moreextensively studied because it is of in-creased relevance in elderly people. Prev-alence rates between 60% and 90% havebeen demonstrated for aging populationgroups.11 The susceptible sites (the rootsurfaces of teeth) are exposed almost uni-versally with increased age and hencethere is greater risk of caries activity.Recent data have also confirmed the as-sociation between root caries activity andfrequency of dietary sugar intake, as wellas quality of oral hygiene and the wearingof partial dentures. 11,57 Men tend to havemore frequent sugar intakes. The frequen-cy of such intakes was also much greateri n a sample drawn from people living inl ong-stay care institutions.

Active root caries is a condition con-centrated within a small proportion of thepopulation (80% of root caries lesions arepresent in about 20% of the population 60).

Again, the older the subject, the more like-ly he or she is to have experienced rootcaries and to have current untreated rootcaries.

Periodontal DiseaseThe effects of periodontal destruction aremore severe in elderly people. 32,43,62 I nsome patients, this includes marked gin-gival recession in the absence of overtdisease. 50 The pattern of periodontal de-struction seen in elderly people appears tobe different from that of the young. Shallowperiodontal pockets are less likely toprogress than deep pockets in an elderlypatient. This is probably a consequence oftwo factors. First, there is a survivor effectin that those people who have teeth whenthey are 65 years of age are not likely to beamong the groups most susceptible to

21 6

Oral Health Status of Elderly People

periodontal breakdown. Second, there arealterations in the immune response withage that modify the pattern of disease ac-tivity. 13,14,20

Oral Health BehaviorsOral health behaviors are influenced bydental status. Relatively few edentuloussubjects attend the dentist for routine in-spection when compared with the dentate(13% to 15% compared with 55% to 65%).Even among the dentate, the rates of ser-vice utilization fall with increasing age, de-spite reported satisfaction with oral healthdecreasing and complaints about oralhealth and dentures increasing. 56,58 Thisdichotomy is likely to be a manifestation ofa general stoicism often found among theelderly: Things go wrong as people getolder and not everything can be fixed. Inaddition, a person with serious healthproblems may regard minor oral healthconcerns as relatively trivial and becomehabituated to them.

There is also a decline in dental atten-dance among the dentate with increasingage. This decline is manifest more in men,which is of some concern because mentend to have more caries in retained teeththan do women. 43,62 MacEntee et al havetried to identify the reasons for this alteredattitude toward oral health. 33 Two quota-tions from their paper illustrate these points.

"I don't think 1 need to go to a dentist be-cause my mouth is free of pain and chew-ing fairly well." "If your general health isgood, you've got enough on the ball to lookafter your teeth. If your general health isn'tgood, maybe you haven't got enough en-ergy to go out to the dentist."

There are a number of variables that in-fluence oral health behaviors.

There are very real financial constraintson the uptake of care in some parts ofthe world.46,54,58,61,62

Fear remains a factor, even in elderlypeople. The frequency of reported anx-iety is lower in elderly patients com-pared with the young; nevertheless,25% to 35% of elderly patients expresshigh levels of anxiety in relation to oralhealth care. 17

The habits of youth are perpetuated intoold age.

I f attendance at the dentist as a socialactivity is not a routine while people areyoung, it does not become so as they agewithout a significant effort in terms ofbehavioral modification. In orderto modifyan individual's behavior, one must first ed-ucate the person about the condition sothat he or she recognizes that an undesir-able change has taken place, rather thansimply ignoring it. Individuals then have tobe taught the appropriate priority for thechange they have identified in terms ofseverity, novelty, or meaning before theyare then equipped to respond in an ap-propriate manner to a sign or symp-tom.25-27,47,48

Some oral health behaviors are aroutine part of life, for example, personaloral hygiene: "The first thing you do in themorning is to brush your teeth and if you'rea floss person you use dental floss. Youdon't want to go around breathing on peo-ple and knocking them over. Oh, disgust-ing thought."

Other behaviors such as dental atten-dance are a consequence of problem solv-i ng on behalf of the individual. The need toattend is triggered by a physical or socialstimulus; unfortunately, the significance ofsuch stimuli reduce with increasing age.

217


We have already noted that personaloral hygiene is part of a social regimen andthe majority of the older population reportfrequent oral hygiene practices (52% ofthe population older than 85 years reportbrushing their teeth twice daily or more) . 5 7

Sadly, this personal oral hygiene is ineffec-tive in the majority of people. In the samesurvey, many people had large quantitiesof plaque in many sites. Again, the prob-lem is one of routine; the routine that wasestablished when an individual was youngis no longer satisfactory in older age. Theoral architecture changes with gingival re-cession. People become less dexterousand less able to manipulate some oral hy-giene aids. Consequently, there is a needfor retraining among elderly people that ispoorly recognised and for which the up-take is poor. Strategies that are associatedwith success in oral hygiene interventionsfor elderly subjects include involving the in-dividuals in the education process. A sim-ple strategy of telling people what to do isi neffective. 21,26,31,47 Furthermore, trainingthe participants in techniques for self orpeer monitoring of oral hygiene has a pos-i tive effect on the outcome of the interven-tion. One program that has delivered im-provement in personal oral health care isPRECEDE (predisposing, reinforcing, andenabling courses in educational diagnosisand evaluation ).29 This program resultedi n improved oral health status and agreater sense of control on behalf of theparticipants. The negative aspect of thisprogram was its cost and that the samplewas self-selected and hence may have hadmore motivation to succeed. Nevertheless,this intensive intervention gives some inter-esting directions for future developments.

Masticatory FunctionAs a broad generalization, chewing abilitydeclines with a reduction in the numberof functional pairs of natural teeth. Thei mpact of this reduction is limited whenthere - are 21 or more teeth remaining,corresponding to the shortened dentalarch. 1,6,7,16,22,30,45 However, where thereare fewer than 21 teeth present, there isa need to rely increasingly on a partialdenture as an adjunct to function, 56 andobjectively measured masticatory efficien-cy is reduced with or without the use ofpartial dentures. 16

Masticatory efficiency with dentures ispoorer than that with natural teeth. Theleast effective combination, from a masti-catory standpoint, appears to be a naturaldentition in one jaw opposed by a com-plete denture in the opposing jaw.

Oral Health and Nutrition

A logical extension of the previous discus-sion on masticatory efficiency would bethat reduced chewing ability would influ-ence nutritional status. This area of workhas been somewhat neglected; however,there is some data available, most recent-ly from the National Diet and NutritionSurvey (NDNS) for people 65 years andolder in the UK. 57 A comparable study hasbeen conducted in the USA58 ; unfortu-nately, as yet no analysis of the relation-ships between oral health and nutritionalstatus have been conducted on thesedata. Farrell established some time agothat chewing was not necessarily requiredfor digestion of a modern diet. 9,10 How-ever, inefficient masticatory ability influ-ences food choice, which in turn has an ef-fect on both intake and nutritional status in

21 8

Oral Health and Nutrition

elderly subjects. People with reducedmasticatory efficiency are less able to eatfoods that require rigorous mastication, forexample, apples, raw carrots, nuts, toast,tomatoes, crisps, and oranges. This rela-tionship is valid for both those with re-duced numbers of teeth in the natural den-tition and those who are edentate. 6,57

These variations in ability to eat foodare also reflected in variations in nutrientintake in relation to intrinsic and milk sug-ars and nonstarch polysaccharide in den-tate subjects. The greater the number ofpairs of anterior and posterior occludingteeth present in older people, the moreintrinsic and milk sugars and nonstarchpolysaccharides they consume. 44,57 Pro-tein, intrinsic and milk sugars, calcium,nonheme iron, niacin, and vitamin C intakeare also reduced in the edentate com-pared with the dentate.18.35,57

Finally, hematologic and biochemicalmeasures of nutritional status are also in-

fluenced by oral health status. Plasmaascorbate (vitamin C) is reduced in eden-tate subjects and in those with fewer pairsof opposing teeth. Plasma retinol (vitaminA) and (a-tocopherol (vitamin E) levelswere also reduced in edentate subjectscompared with the dentate. 57

The impact of these nutritional deficien-cies is unclear. It is worthy of note that inaddition to the above data, some of thesubgroups within the NDNS survey hadparticularly poor nutritional status forspecific micronutrients. For example, themedian plasma ascorbate level for eden-tate subjects living in an institution was11.4 umol I -1 , which is at the extreme low-er range of normal. By definition, 50% ofthis sample would have plasma ascorbatelevels lower than this value. This is of par-ticular concern when the associations be-tween vitamin C and respiratory function,stroke, and cardiovascular disease are taken into cons ideration. 910,18,24,28,35,37-39,44

21 9


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22 2

Chapter 16

Operative Treatment for Elderly People

Michael J. Noack, Michael Wicht, and Angus W.G. Walls

Root Caries

Both root caries and coronary caries resultfrom the multifactorial interaction ofbacterial plaque, dietary carbohydrates,and susceptible tooth surfaces. However,there are differences between crown androot caries. Acidogenic bacteria such asmutans streptococci and lactobacilli areassociated strongly with active root carieslesions and coronal disease. However,the role of other pathogens, especiallyActinomyces species, is not fully under-stood. Table 16-1 summarizes the evi-dence of bacterial pathogenes implicatedi n root caries . 2o

I n initial empirical discussions, darkbrown lesions were described as inactive,whereas soft yellowish lesions were ac-tive. 15 The same authors demonstratedthe transition from active to inactive lesionsin a follow-up study where meticuloustoothbrushing using a fluoride-containingtoothpaste facilitated the transition of ac-tive lesions into inactive ones. The transi-tion was characterized by a change fromyellow, soft friable surfaces to leathery orhard dark surfaces. 14 However, recent evi-dence suggests that changes in color arean oversimplification of various stages ofpathogenesis of root caries and that nocorrelation between bacterial contamina-

Table 16-1 Evidence implicating bacterial species in root surface caries 20

223


tion and color has been shown. 1 2

Therefore, clinical diagnosis must rely onthe texture of the surface of the lesion andi ts location, as well as the extent of the de-fect.

I t is advantageous to determine theamount of mutans streptococci in plaquecovering root caries lesions to assist withclinical treatment decisions. 13 However,within i nfected dentin Actinomycesspecies bacteria, especially A naeslundii,play a significant role. 3 The pathogen-esis is not entirely understood becauseActinomyces species bacteria do notcause relevant collagen degradation. 5

The decision on the most appropriatetreatment modality (restoration or che-motherapeutic control) needs to be basedon an assessment of caries risk and thel i kelihood of lesion progression. Invasiverestorative procedures are not always nec-essary unless major cavitation is clinicallyapparent.

224

Noninvasive Therapy andPrevention

Although fluorides inhibit mineral loss dur-ing acid demineralization and enhanceremineralization,7 the therapeutic effect offluorides in high-risk situations is limited.11Besides a preventive program focusing onoral hygiene measures and decreasing thefrequency of sugar intake, 16 two optionsare discussed for arresting initial lesionsand preventing progression:

1. Reduction or elimination of pathogenesby means of antibacterial varnishes orgels

2. Increasing host resistance against acidattack by means of sealing root surfaceswith adhesive

An overview of antimicrobial varnishesi s given in Table 16-2. The varnish Cervitechas a low concentration of chlorhexidinewith 1 % thymol (to improve its substantivi-ty). It showed promising results in labora-tory and clinical assessments.10 However,

Noninvasive Therapy and Prevention

Fig 16-1 After scaling and seal-i ng of the root caries lesion, fur-ther demineralization (laser fluo-rescence, Diagnodent) was pre-

vented over 6 months, despiteplaque accumulation.

clinical studies have failed to demonstratea clinically relevant therapeutic effect. 6 I ncontrast, the highly concentrated chlor-hexidine varnish EC 40 was found to ef-fectively prevent root caries of abutmentteeth.11 Even a 20% chlorhexidine varnishsuppressed mutans streptococci over aperiod of months when covered with al ight-cured nonfunctional bonding resin.$I nterestingly, treatment with resin alonewas statistically less effective, but differ-ences between the results were small.

As an alternative to an antimicrobialagent, attempts have been made to protectroot surfaces by sealing with dentinal ad-hesives. In simulating caries demineraliza-tion in vitro, the preventive effect of sealingdentinal surfaces was demonstrated. 9,18A new attempt was made to use a triclosanreleasing resin as protection against rootcaries as well as cervical abrasion.Preliminary results showed that deminer-alization could be prevented by means ofsealing root surfaces. 19 However, a reduc-tion in pathogenes was not observed. Insome cases demineralization was prevent-

ed despite plaque accumulation on sur-faces at risk, as shown in Fig 16-1.

Figure 16-2 summarizes the recom-mendations for the treatment of root carieslesions. In general, it can be recommend-ed to remove superficial carious layers andto smooth root surfaces with a curettebefore the application of a sealant or an-tibacterial varnish, as shown in Fig 16-3. 1,2

Although there are some indications thatsealing is more effective than chlorhexi-dine therapy, conclusive clinical studiesare not yet available. In the event that rootcaries lesions are subgingival, access is of-ten only possible by means of periodontalsurgery.

I f cavitation necessitates restoration ofthe defect, there is no need to extendpreparation into sound dentin. Restoringand sealing can be combined, thereby lim-iting cavity preparation to the central cariesdefect, followed by sealing of the sur-rounding initial defect. Quite often this isthe only way to manage circumferentialroot caries.

225


Fig 16-2 Treatment decisions for various stages of root caries.

226

Noninvasive Therapy and Prevention

Fig 16-3 Extensive restoration ofi nitial root caries lesions is notrequired. Superficially infectedand softened dentin can besmoothed and then sealed with adentinal adhesive.

There are few data available to help theclinician choose the most appropriaterestorative material. Composites and, inparticular, flowable resins, compomers,and glass-ionomer cements, as well asresin-modified ionomers and amalgam,may be used . 4 Because tooth-colored ma-terials can be combined with sealing tech-niques, they are probably more advanta-geous. However, in clinical situations theskill of the operator is more important tothe survival of the restoration than the ma-terials selected.

I n addition, possible techniques to ar-rest root caries lesions by applying an-tibacterial varnishes and sealing dentinalsurfaces have advantages in the preven-tive treatment of high-risk patients.Notwithstanding systemic factors and thepatient's previous experience with coronaland root caries, prosthodontic treatmentmust be considered to be an independentrisk factor. 11,17

22 7


References

1. Banting DW, Ellen RP. Carious lesions on theroots of teeth: A review for the general practi-tioner. J Can Dent Assoc 1976;42:496-504.

2. Billings RJ, Brown LR, Kaster AG. Contemp-orary treatment strategies for root surface den-tal caries. Gerodontics 1985;1:20-27.

3. Bowden GH, Nolette N, Ryding H, CleghornBM. The diversity and distribution of the pre-dominant ribotypes of Actinomyces naeslundiigenospecies 1 and 2 in samples from enameland from healthy and carious root surfaces ofteeth. J Dent Res 1999;78:1800-1809.

4. Burgess JO. Mental materials forthe restorationof root surface caries. Am J Dent 1995;8:342-351.

5. Dung TZ, Liu AH. Molecular pathogenesis ofroot dentin caries. Oral Dis 1999;5:92-99.

6. Ekenback S, Linder L, Lonnies H. Effect of fourdental varnishes on the colonization of cario-genic bacteria on exposed sound root surfaces.Caries Res 2000;34:70-74.

7. Featherstone JD. Fluoride, remineralization androot caries. Am J Dent 1994;7:271-274.

8. Fure S, Emilson CG. Effect of chlorhexidinegel treatment supplemented with chlorhexidinevarnish and resin on mutans streptococci andActinomyces on root surfaces. Caries Res1990;24:242-247.

9. Grogono AL, Mayo JA. Prevention of root carieswith dentin adhesives. Am J Dent 1994;7:89-90.

1 0. Huizinga ED, Ruben J, Arends J. Effect of ananti microbial-containing varnish on root dem-i neralisation in situ. Caries Res 1990;24:130-132.

11. Keltjens HM, Schaeken MJ, van der Hoeven JS,Hendriks JC. Caries control in overdenture pa-tients:18-month evaluation on fluoride andchlorhexidine therapies. Caries Res 1990;24:371-375.

12. Lynch E, Beighton D. A comparison of primaryroot caries lesions classified according tocolour. Caries Res 1994;28:233-239.

13. Lynch E, Beighton D. Relationships betweenmutans streptococci and perceived treatmentneed of primary root-caries lesions. Gerodont-ology 1993;10:98-104.

14. Nyvad B, Fejerskov 0. Active root surface cariesconverted into inactive caries as a response tooral hygiene. Scand J Dent Res 1986;94:281-284.

1 5. Nyvad B, Fejerskov 0. Root surface caries:Clinical, histopathological and microbiologicalfeatures and clinical implications. Int Dent J1 982;32:311-326.

16. Papas AS, Joshi A, Belanger AJ, Kent RL Jr,Palmer CA, DePaola PF. Dietary models for rootcaries. Am J Clin Nutr 1995;61:417-422.

17. SteeleJG, Walls AW, Murray JJ. Partial denturesas an independent indicator of root caries risk ina group of older adults. Gerodontology1997;14: 67-74.

18. Swift EJ, Hammel SA, Perdigao J, Wefel JS.Prevention of root surface caries using a dentaladhesive. J Am Dent Assoc 1994;125:571-576.

19. Wicht M, Haak R, Lummert D, Noack MJ. Non-restorative treatment of root caries lesion withchlorhexidine containing varnishes and dentinesealants. Am J Dent (in press).

20. Zambon JJ, Kasprzak SA. The microbiologyand histopathology of human root caries. Am JDent 1995;8:323-328.

228

Chapter 17

Adhesive Techniques for the Management ofFractured and Worn Teeth in Elderly Patients

Angus W.G. Walls

I ntroduction

The advent of effective adhesive resinsprovides the opportunity to attach a varietyof restorative materials in a predictable wayto both enamel and dentin. There are, how-ever, age-associated changes in the struc-ture of both enamel and dentin that affectthe ability to bond to these surfaces. Thischapter reviews these changes and de-scribes strategies for the use of adhesivesduring the management of fractured andworn teeth in elderly patients.

Age Changes in Dental Tissues

Age Changes in EnamelThe chemical structure of enamel chan-ges little with age. However, there arechanges to the surface layers of enamelthat make orally exposed enamel resistantto demineralization. These changes arebeneficial in helping to prevent caries butneed to be taken into account when etch-ing the enamel surface prior to bonding.The changes affect the surface enamelalone and do not affect freshly preparedenamel.

Whenever acid is present in the mouth,be it in the form of food, beverages, orregurgitated stomach acid, the surface ofthe enamel of the teeth will start to dis-solve. Once the acid has been neutralizedby the buffering and washing effects ofsaliva and to an extent through the disso-lution of surface enamel, the opportunityi s available for remineralization of thedemineralized enamel surface. This rem-ineralization takes place from saliva inthe presence of calcium, hydroxyl, andphosphate ions. However, there are otherionic species present in saliva includingfluoride, zinc, and manganese. Remineral-i zation in such a mineral soup is not simplya matter of regeneration of hydroxyapatite.I onic substitutions occur within the crystallattice, including fluoride for hydroxyl andmanganese and zinc for calcium. Thephysical chemistry of this process resultsin a crystal structure that is more stablethan classical apatite. The surface is also,however, amorphous, without the charac-teristic organization of the enamel rods.

Reliance is placed upon the organiza-tion and orientation of the enamel rods toproduce the irregular porous pattern asso-ciated with etched enamel. The more sta-ble amorphous crystal structure found onthe surface is less susceptible to etching

229

Adhesive Techniques for the Management of Fractured and Worn Teeth in Elderly Patients

Fig 17-1 Scanning electron micrograph illustratingvariations in etching patterns seen on unpreparedenamel.

and is likely to be responsible for the widevariation in etch patterns seen on unpre-pared enamel surfaces (Fig 17-1).Attachment to such a surface is lesspredictable. The etching time should bei ncreased orthe surface of the enamel pre-pared to remove this layer. This is of signif-icance when bonding structures to apreviously orally exposed surface ratherthan a newly prepared surface.

Age Changes in DentinDentin undergoes age-associated chan-ge in two ways. When the dentin is ex-posed in the mouth, alterations similar tothose that occur in enamel are evident inthe dentinal surface. Consequently, previ-ously orally exposed surfaces of dentin willhave an altered surface structure whencompared with a surface that has not beenexposed to saliva. This may influence thequality of the attachment that can beachieved to noncarious cervical lesions,for example.

Dentin also undergoes alterations in itsinternal structure as a consequence of ag-ing. The changes are more profound inareas where the surface of the dentin hasbeen exposed in the mouth or wherecaries has extended to involve the dentin.The changes result in deposition of miner-alized tissue within the dentinal tubules(peritubular dentin), causing a diminutionof the diameter of the dentinal tubules. Theextent of deposition of peritubular dentin isgreater toward the periphery of thetubules.

The effect of this change varies with theproximity of the dentin to the pulp. Thetubule density within dentin changes asthe tubules radiate outward from the pulptoward the tooth surface. The diametervaries as described above. The combina-tion of these effects results in marked vari-ation in the proportion of tubules to miner-alized tissue with the depth of the dentinrelative to the pulp.

Penetration of resin into the dentinaltubules is responsible for between 25%and 40% of the attachment strengthbetween composite resin and tooth.Obviously, the magnitude of this benefitdepends on both the tubule densityand, to an extent, the tubule diameter.Complete occlusion of the tubules, form-i ng sclerotic dentin, does occur andresults in a marked reduction in bondstrength to levels at which there is sub-stantial risk of failure of the bond undertheforces of polymerization contraction. Thisphenomenon has been used to explainthe relatively poor performance of certainadhesive resins when repairing noncari-ous cervical defects.1

230

Surface Treatments

CommentThe benefit of an adhesive is the abilityto bond materials or structures to toothtissue. This can be used both to enhanceretention in tooth preparations of limitedheight and to limit the extent of toothreduction necessary for the mechanicalretention of restorations. The extent towhich these benefits can be relied on inaged teeth will be influenced by the extentof the age-related changes in the surfacesselected for bonding. The design of anyrestoration needs to take into account thepotential for reduction in bond strength.

Fractured teethCuspal fracture is a problem associatedwith function of the teeth. It is more com-mon in elderly people and in teeth thathave been previously restored, particularlywith intracoronal restorations of amalgamor gold (Fig 17-2a). The fractured cusp hastraditionally been replaced using someform of mechanical accessory retention,commonly self-threading pins. Pins causecrazing within the dentin and weaken theamalgam restoration. Some would sug-gest that a tooth restored with a large pin-retained restoration subsequently shouldbe crowned. This results in further lossof sound tooth tissue. The option of anadhesively retained restoration reducesthe extent of tooth preparation required.The material used needs to be able to with-stand the functional loads to which it maybe subjected. There are concerns aboutthe ability of composite resin to replacecusps because they tend to undergo sig-nificant levels of wear. The options wouldbe a cast metal, porcelain-fused-to-metal(Figs 17-2b and 17-2c), or an all-porcelainrestoration (Fig 17-3).

The fitting surface of these restorationsneeds to be treated to ensure an adequatel evel of bond strength to the adhesivebeing used. The nature of the surface treat-ment is also influenced to an extent by theadhesive that is to be used and its mecha-nisms of attachment to the metal orceramic surface.

Surface Treatments

Cast Precious MetalsSome adhesives will bond effectively to aroughened gold surface. The surface ofthe restoration should be sandblasted with40 mm of silica and then steam cleaned.The surface of gold restorations that con-tain more than 8% copper can also be heattreated to produce a stable copper oxidel ayer on the surface of the restoration. Therestoration should be finished to a highshine on the functional surface. It shouldthen be heated to about 400°C for 10 min-utes in air. The surface of the casting willbecome black as a result of oxidation andshould be returned to the clinician in thiscondition. Any attempt to polish the non-fitting surface of the tooth is likely to resulti n contamination of the oxidized goldfitting surface, which would reduce the at-tachment strength of the adhesive lute.

Cast Nonprecious MetalNonprecious metals remain corrosion-freeas a consequence of a stable oxide layerl i miting the surface of the alloy. Adhesivel uting agents can be bonded to such oxidelayers. The surface treatment shouldoptimize the production of the oxide layer

231

Adhesive Techniques for the Management of Gractured and Worn Teeth in Elderly Patients

Fig 17-2a Fractured buccal cusp on a max-i ll ary first premolar.

Fig 17-2b Porcelain fused to precious metal(PFM) addition made to replace the missingtooth structure.

Fig 17-2c The PFM addition bonded in placeusing C&B Metabond. This restoration hasfunctioned satisfactorily for 9 years.

Fig 17-3 Buccal cusp replacement using anall-porcelain bonded addition. The restorationwas bonded in place with a dentine-bondingagent (All-Bond) and a porcelain laminateveneer luting system.

232

Composite Resin

by sandblasting the metal surface thensteam cleaning.

Porcelain SurfacesConventional dental porcelains can beetched with hydrofluoric acid to produce amicroporous surface analogous to etchedenamel. This surface should then be coat-ed with a silane-coupling agent to maxi-mize the attachment strength to the resin(Figs 17-4a to 17-4c).

Unfortunately, some of the recently de-veloped high-strength materials cannot beetched in this way (eg, In-Ceram); conse-quently, they are not suitable for use whenthe adhesive is to be a major source of re-tention for the restoration.

Tooth Wear

Tooth wear is a problem of increasing con-cern to the profession. Wear is normally re-l ated to oral function; however, in some pa-tients wear occurs at an abnormal rate.Both normal and abnormal wear cancause esthetic and possibly functionalproblems in elderly dentate patients.

Adhesively retained restorations offerbenefits in terms of increasing the attach-ment strength of restorations to teeth withshort or convergent crown preparationsand allow the clinician to add structuresdirectly to worn tooth surfaces withoutpreparation of the teeth, thus preservingsound tooth tissue.

A thorough assessment of the etiologyof a wear problem is an essential precur-sor to its management. Whenever possi-ble, the etiology should be identified and,i f practical, controlled prior to commenc-i ng complex restorative care. This is of par-

ticular importance in erosive wear whenongoing erosive damage can threaten thelongevity of restorations (Fig 17-5) and inattritive pattern wearwhen the final restora-tion is likely to be subjected to high func-tional loads if the patient continues toclench or grind his or her teeth (Fig 17-6).

Composite Resin

Composite resin has relatively poor wearresistance. Consequently, it is not suitableas a long-term restorative material for thereconstruction of the functional surfacesof multiple teeth. However, it can be veryuseful as a durable, transitional restorativematerial during the management of a worndentition, particularly when an increase inthe occlusal vertical dimension is planned(Figs 17-7a to 17-7c). Also, it has been sug-gested that composite resin is an appro-priate material for use in the medium-termmanagement of patients with erosive toothwear. The rationale for this approach isthat composite resin can be added to orrepaired. Hence, if there is any continua-tion of erosion that would result in loss oftooth structure around the margins of therestoration, further material can be addedto reduce the possibility of caries occur-ring at the margins of the restoration.

233


Fig 17-4a

Maxillary second premolar with

Fig 17-4b All-porcelain restoration to replacefractured buccal and palatal cusps.

both cusps. The restoration was bonded inplace with a dentin-bonding agent (GLUMA)and a porcelain laminate veneer luting system.

Fig 17-4c Restoration after 10 years of clini-cal services, showing some marginal staining.

234

Composite Resin

Fig 17-5 Ongoing erosive pattern tooth weararound the margins of adhesively retained additionsto 25 and 26 in apatient with uncontrolled gastricreflux associated with a hiatus hernia.

Fig 17-6 Fracture of porcelain from the occlusalsurface of a porcelain-used-to-metal restoration in apatient with a bruxing and grinding habit. There wasi nadequate space within the occulsion for an ade-quately retentive preparation of both porcelain andmetal in this case.

Fig 17-7a Mixed erosive and functional wear onthe surfaces of 45 and 46 in a patient for whom therestorative process included an increase in the oc-clusal vertical dimension.

Fig 17-7b Laboratory-made composite resin on-lays for 45 and 46 to restore occlusal form and func-tion with ease of control of the occlusal morphology.

Fig 17-7c The restorations shown in Fig 17-7b lut-ed in place using an adhesive technique onto theteeth shown in Fig 17-7a. Mirror occlusal adjust-ment only was required at this stage.

235


Fig 17-8a Worn occlusal surface in a molartooth.

Fig 17-8b Oxidized precious metal castingprior to bonding to the tooth surface.

Fig 17-8c Occlusal spacer bonded in placeusing Panavia 21.

Fig 17-8d Metal spacer in place afterocclusaladjustment and polishing.

Laboratory-Made Restorations

Adhesive luting agents can be used toattach metal (Figs 17-8a to 17-8d), porce-l ain-fused-to-metal (Figs 17-9a to 17-9d), orporcelain additions to tooth structure (Figs17-10a to 17-10d). The design of suchrestorations needs to be undertaken withthe same level of care as is used for con-

ventional restorations, particularly when areorganized occlusal scheme is planned.Mounted study casts and a diagnosticwaxup are useful in guiding the clinicianand the technician in the design of suchrestorations, particularly with regard to thepattern of dynamic tooth contacts that willbe developed on the new restorations.

236

Laboratory-Made Restorations

Figs 17-9a to 17-9d Reconstruction.

Fig 17-9a Extensive functional wear of themandibular anterior teeth in a patient with a clench-i ng/grinding habit.

Fig 17-9b Following reconstruction in the maxillaryarch using porcelain-fused-to-metal crown andbridge work and adhesive porcelain additions in themandibular arch.

Fig 17-9c Ten years postrestoration. There hasbeen considerable functional wear of the adhesiveadditions. The buccal extensions all fractured with-i n 12 months of placement.

Fig 17-9d Functional wear on the palatal surfaceof the porcelain-fused-to-metal crowns in the op-posing arch.

23 7


Fig 17-10a to 17-10d Anterior tooth wear.

Fig 17-10a Worn buccal and incisal surfaces inmandibular anterior teeth.

Fig 17-10b Porcelain additions to teeth 43, 31, 32,and 33 (41 is missing).

Fig 17-10c Porcelain addition to 43 eleven yearsafter placement. There has been some wear or asmall fracture at its mesial marginal edge, butotherwise the restoration continues to function.Note the change in color of the teeth compared withFig 17-10b as a consequence of aging.

Fig 17-10d Porcelain restorations 11 years later,showing some marginal staining. These restora-tions were functioning against porcelain surfaces inthe maxillary arch.

238

Reference

Conclusions

Reference

The bond strength of resin to dentin and

1. Yoshiyama M, Sano H, Ebisu S, et al. Regional

enamel

may

be

affected

adversely

i n

strengths of bonding agents to cervical sclerot-

elderly people as a consequence of age-

i s root dentin. J Dent Res 1996;75: 1404-1413.

associated change in the dental tissues.This can reduce the effectiveness of ad-hesive restorative materials in elderly peo-ple and needs to be taken into accountwhen both planning treatment and de-signing restorations.

The use of adhesive resins offers theclinician a range of options when planningcare for fractured and worn teeth. Thesetechniques offer the opportunity to mini-mize preparation of otherwise sound resid-ual tooth tissue. They may also make arestorative option practical on teeth withshort clinical crowns.

239

Chapter 18

Conservative Dentistry:Educational Patterns in Europe

Alphons J.M. Plasschaert and Sandro Rengo

Introduction

I n discussing educational patterns ofconservative dentistry in Europe, the termconservative dentistry has to be defined.Conservative dentistry has to do with theconservation of teeth, damaged by variousforms of multietiologic disease, includingdental caries, erosion, abrasion, attrition,wear, and trauma. It comprises the etiolo-gy, pathology, and applied prevention ofthese diseases as well as restorative thera-py. In Anglo-American literature a more re-stricted definition of operative dentistry isused: "Operative dentistry is the art andscience that relates to the diagnosis, treat-ment, and prognosis of those defects ofteeth which do not require full coverage forcorrection; to the restoration of propertooth form, function, and esthetics; and tothe maintenance of the physiological in-tegrity of the teeth ."4 For the sake of clarityand by way of introduction to the subjectmatter of this chapter, the term conserva-tive dentistry will be used in its most re-stricted sense, namely: "The theory andpractice of diagnosing and restoring de-fects in teeth with direct restorative materi-als (mainly amalgam and direct tooth-col-ored restoratives)."

If we want to know where we are todayconcerning educational patterns in the

field of conservative dentistry, it is helpfulto analyze the developments in the last 20to 30 years according to:

1. Content2. Education3. Europe

This analysis provides the platform forcontributions from various dental schoolsin Europe and for further discussion.

Content of ConservativeDentistry

It is amazing to realize what enormousdevelopments and progressive steps havebeen made in conservative dentistry inthe last century. Concerning diagnosis, im-provements have been made in the fieldof caries diagnosis using radiography, no-tably in relation to film speed and radiationprotection. More interesting and promis-ing, however, is the introduction of digitalradiography and the use of computers fori mage enhancement, storage, and transfer.

Although solutions to disclose dentalplaque have been in use for severaldecades, it was Fusayama3 who first advo-cated the use of acid red as a disclosingsolution for decayed dentin. This approach

241

Conservative Dentistry: Educational Patterns in Europe

has been introduced in several dentalschools. A new concept developed inSweden is Carisolv (Medi Team AB,Savedalen, Sweden), whereby caries isdissolved away with the aid of hand instru-ments rather than mechanically removedwith a bur.

I n the area of liners and bases a dra-matic shift has occurred in the last decade.Until the 1990s zinc oxide-eugenol, calci-um hydroxide, and zinc phosphate ce-ments together with some varnishes (eg,Copalite) were the materials of choice.Then polycarboxylate and glass-ionomercements became more dominant. Latelythe need for any of these materials hasbeen questioned, on the assumption thatthe most important protection when usingcomposite filling materials is the sealing ofthe dentinal tubules to keep out any bac-teria or other irritants. Thermal isolation isless important with the use of compositeswhen compared with the use of metallicamalgam. It is of interest to share the opin-ions and policies of dental schools inEurope in this respect.

Undoubtedly, the most important de-velopment in recent times has been thei ntroduction of adhesive techniques incombination with, in particular, compositefilling materials. After the introduction ofhigh-speed cavity preparation with dia-mond and tungsten carbide burs, adhe-sive technology and procedures werethe most important evolutionary develop-ments in conservative dentistry of the lastcentury. We are now able to teach newgenerations of dentists to save tooth struc-ture by removing decayed enamel anddentin only and reinforcing the weakenedremaining hard tissues through the adhe-sive bonding of strong, wear-resistant,tooth-colored materials. The major prob-

lems of these materials in the 1980s werewear resistance and polymerizationshrinkage. However, progress in the devel-opment of improved products has madeavailable materials in which these twoproblems have been reduced to a clinical-l y acceptable level.

We are in the process of making thechange from Black's principles for cavitypreparation for amalgam (Figs 18-1 a to 18-1d) to tooth-saving, adhesive restorativeprocedures using bonding agents andtooth-colored filling materials (Figs 18-2ato18-2d). The extent to which this change isreflected in the programs of dental schoolsi n Europe remains largely unknown.Recently, Wilson and Mjor5 published theresults of a descriptive study on the teach-i ng of Class I and Class II direct compositerestorations in European dental schools.Data from 104 dental schools out of a totalof 185 schools were included in the study.All but 4 of the 104 participating schoolswere found to teach the use of compositesin Class I and Class II, two-surface situa-tions, at least in premolar teeth. The num-ber of participating schools that consid-ered premolar and permanent molar teethsuitable for restoration by means of ClassI and two- and three-surface Class II com-posites is represented in Fig 18-3. Therewas almost full agreement with respect tothe suitability of premolar teeth for restora-tion by means of posterior composites andi n relation to permanent molars for restora-tion by means of Class I posterior com-posites. In contrast, less agreement wasfound in relation to the suitability ofpermanent molars to receive two- and es-pecially three-surface composites. Thesuitability of premolars for three-surfacecomposites was found to be similar to thesuitability of permanent molars for two-

242

Content of Conservative Dentistry

Figs 18-1a to 18-1d An amalgam restoration in a Class II cavity preparation according to G.V. Black'sclassification.

Fig 18-1a Occlusal cavity preparation. Fig 18-1b Cavity preparation with matrix andwedges.

Fig 18-1c Carved amalgam restoration. Fig 18-1d Final polished amalgam restorations.

surface composites. Similar findings wereobtained for the four geographic regionsof Northern and Central Europe, Scandi-navia, Southern Europe, and EasternEurope (Table 18-1). As to the occlusalwidth of the preparation for Class I andClass II composite restorations, mostschools considered < 1/3 of the occlusalwidth as acceptable in both premolar andpermanent molar teeth (Fig 18-4).Limitations in relation to the use of com-posites in posterior teeth were most

common in respect of the gingival marginbeing apical to the cementoenamel junc-tion. In contrast, relatively few schoolsi ndicated any limitation in terms of the buc-colingual width and axial depth of proximalboxes (Fig 18-5). It should be noted thatamong European dental schools, therewas almost full agreement on an anitcipat-ed increase in the proportion of the dentalcurriculum in operative/conservative den-tistry to be devoted to the use of resin-based materials in posterior teeth.

243


Figs 18-2a to 18-2d A modern hard tissue-saving cavity preparation restored with composite filling ma-terial using an acid-etch adhesive technique (courtesy of Dr. J. Roeters).

Fig 18-2a Decayed first molar.

Fig 18-2b Initial tooth-saving cavity preparation.

Fig 18-2c Disclosing solution applied.

Fig 18-2d Final composite restoration.

Table 18-1 Teaching of Class I and Class II composites according to geographic regions

244

Content of Conservative Dentistry

Fig 18-3 Number of schools( N=100) that considered premo-lar and permanent molar teethsuitable for restoration by means

of Class I and two- and three-sur-face Class II composites . 5

Fig 18-4 Number of schools( N=100) indicating limitations fordirect composites in premolarand permanent molar teeth interms of the extent of the occlusalwidth of the preparation 5

Fig 18-5 Number of schools( N--100) indicating limitations onthe size of the proximal box inClass II preparations to be re-stored with a composite, 5

245


Education in ConservativeDentistry

The combination of two major develop-ments, one in learning in general and theother in the teaching of conservative den-tistry will have a definite impact. Thesedevelopments are the introduction of prob-lem-based learning by educational psy-chologists, and the explosion in the avail-ability of information computer technology.Problem-based learning does not empha-size the reproduction of facts and figures,but is more directed toward having stu-dents solve dental problems in patients bysearching for what is known about theproblem through evidence-based den-tistry. All information available in the scien-tific literature on a specific subject isaccessable in a structured way throughpractice guidelines in which both practicalclinical evidence and scientific evidence iscombined and adjusted to the specificproblem to be solved. Secondly, the ex-plosion in information computer technolo-gy is leading to a new era in teaching andlearning. Large amounts of information inthe form of text and images are alreadyavailable through the Internet at any timeand any place where dental students haveaccess to an Internet-linked computer.

I n both the theoretical and practicaltraining of conservative dentistry, thesei nnovations are already becoming increas-i ngly visible. Digital lectures and databas-es of educational materials are being puton the Internet at a rapidly growing rate(Fig 18-6). Computer-based learning pro-grams have been developed whereby stu-dents receive feedback on their progressin learning. It is assumed that in the com-i ng years it will be normal for every studentto have access to an Internet-linked com-

puter and to use it in combination with CD-ROM packages. In this way all theoreticalinformation will be accessible to all stu-dents at any place where study is conve-nient (Fig 18-7). For teachers this requiresa shift in activities from presenting infor-mation through lectures to formulatinglearning objectives, selecting learning ma-terials (books, Internet, etc), guiding stu-dents, giving seminars, and developingfeedback and examination tests. The roleof the teacher should therefore be to stim-ulate students in scientific and creativethinking in order to develop a questioningand searching mind.

Teaching and learning of practical psy-chomotor skills in conservative dentistryis complex and demanding of curriculumti me if it is done to an advanced level. Newtechniques do not always replace olderones; therefore, the number of treatmentoptions is always increasing. This meansthat in many programs both amalgam andcomposite restoration procedures are be-ing taught, together with indirect restora-tive techniques (eg, gold and ceramic in-l ays for the restoration of posterior teeth).

I t is interesting to observe the develop-ments in the teaching of skills in laborato-ry facilities. A good example is the DentSimdental unit, also described as the virtual re-ality dental training simulator (Fig 18-8).The functions of this system are to provideindividual interactive training in cavitypreparation skills on a phantom head, re-lated theory and examples, and manage-ment information for the course director.The system's integral computer stores anon-line textbook, patient history data, diag-nostic data, and principles of preparationand criteria for optimal per-formance. It in-cludes three-dimensional tooth modelsand provides hyperlinks to a professional

246

Education in Conservative Dentistry

Fig 16-6 Students are increasingly learningmorethrough digital lectures and databases ofeducational material available on the Internetrather than through the reading of textbooks.

Fig 18-7 Dental schools are making availablecomputer facilities to students for learning andcommunication through e-mail, the Internet,and local learning programs.

Fig 18-8 The DentSim dental unit, describedas a virtual reality dental training simulator, pro-vides individual interactive training in cavitypreparation skills on a phantom head, com-bined with related theory and examples andmanagement information for a course director

24 7


terminal. A number of advantages are be-i ng claimed. Round-the-clock, unlimitedpractice is possible. The clinical environ-ment is simulated and evaluation of skills

i s standardized, objective, and immediate.Training data are stored and can be usedto communicate with a teacher. DentSimclaims to be highly effective in self-learn-i ng, to provide high-quality training, and tobe instrumental in improving communica-tion within and between dental schools.With such technology, the role of the clini-cal instructor may shift from giving livedemonstrations and feedback to the de-velopment of programs and monitoringthe progress of students. Time will showhow important these developments will bei n shaping education in conservative den-tistry in Europe.

To gain sufficient clinical experiencethat will enable the new dental graduatesto practice effectively in general dentalpractice, many schools now commencepreclinical "phantom head" courses in thefirst or second year of their program. Thefirst patients tend to be seen in the secondor third year of a five-year course. Preven-tion, diagnosis, and treatment planningreceive increasing attention as integral el-ements of practical training.

European Developments inConservative Dentistry

The training of dentists in Europe still re-flects the two traditional methods-thesouthern and the northern approaches.The southern approach comprises med-ical training in the first years of dentaleducation, followed by a dental program of1 to 2 years only. In contrast, the northernEuropean countries use the Anglo-Amer-

i can model in which students enter univer-sity from high school to join an i ntegratedcourse of dentistry and medicine from theoutset. To harmonize European dentaleducation programs, the EuropeanEconomic Community ( EEC) i n 1978 iden-tified the profile of the dentist and listed the

subjects to be studied as minimum re-quirements in European dental schools. 1

I n November 1995 the EuropeanCommission of the European Unionadopted the report and recommendationconcerning clinical proficiencies required

for the practice of dentistry i n the

European Union.2 As to the clinical profi-ciencies required in the field of conserva-tive dentistry, the following item can befound in the report (Item 4.10): "Therestoration to function of teeth utilising thefull range of currently acceptable andavailable restorative materials with dueconsideration to the concept of oralhealth." As to the educational process, thereport states: "The acquisition of clinicalproficiency may be achieved through adiversity of educational and training pro-grammes. These may be assessed andexamined in different ways throughout theEuropean Union. Nevertheless it is possi-ble to agree on certain basic clinical profi-ciences common to all member states ofthe EU." Such reference documentation al-l ows dental schools to bring their pro-grams into harmony within the Europeanframework.

At the European level several inititativeshave resulted in a strengthening of cohe-sion in dental education, principallythrough cooperative schemes betweendental schools. These initiatives included:

1. The Association for Dental Education inEurope, founded in 1975 and now sup-

248

European Developments in Conservative Dentistry

ported by the European Journal ofDental Education, which was launchedi n 1997.

2. The European Activity Scheme for theMobility of University Students (ERAS-MUS), now expanded to include easternEurope and renamed "Socrates." Thisprogram has stimulated exchange ofteachers and students between a num-ber of dental schools in Europe. One ofthe positive effects of this program is abetter understanding and increasedrate of change in dental education pro-grams. Education and training in thearea of conservative dentistry is consid-ered to have gained considerably fromthese exchange programs.

3. The DentEd Consortium is a network ofEuropean dental schools established tobuild a system for quality assesment bysite visitation throughout Europe. ThisEuropean network has arranged an im-pressive number of site visits to help fur-ther harmonize dental education inEurope.

The objectives of the network are asfollows:

To establish a network of European in-stitutions involved in dental education,with emphasis on undergraduate edu-cationTo provide a database of informationon dental educational institutions formutual exploitation of available intellec-tual, technical, and clinical resourcesfor the common good of European den-tistryTo promote an understanding of theeducational systems in operationthroughout Europe and provide an ex-planation of the logical and scientific

basis on which they have been devel-opedTo promote the development of aprocess of quality development throughself-assessment combined with peerdiscussion in the dental schools ofEuropeTo encourage the application of evi-dence-based competences in clinicaldentistry in order to promote an objec-tive self-assessment of the scientific evi-dence on which appropriate clinical pro-cedures are taught to studentsTo exchange teams of multinational vis-itors between institutions in order to re-view the different methods of educationand training in the EU in the context ofoutcome, competences, and innovations

Presently, about 75 schools are involvedin the network and the curricula of ap-proximately 20 schools have been as-sessed in the past 18 months (Tables 18-2and 18-3).

I n the field of conservative dentistrythere has been a recent initiative to createa European platform for university teach-ers and general practitioners. This plat-form-the Academy of Operative Dentistry,European Section (AODES)-was estab-lished in Riva del Garda, Italy, in 1998.Subsequently, annual meetings have beenheld in Munich, Germany (1999), andBologna, Italy (2000). The objective of theAODES is to promote excellence in opera-tive dentistry by exerting an influence onthe clinical practice of dental health pro-fessionals, education in dental sciences,research, and in any other realm pertinentto conservative dentistry. It is hoped thatmany more European dentists will supportand contribute to this new organization.

249


Table 18-2 Dental Schools in the European Union participating in DentEd (N=53)

250

Table 18-3

Dental schools outside of the European Union participating in DentEd (N=20)

Conservative Dentistry Training in Europe

Conservative DentistryTraining in Europe

Following are some details of programs inconservative dentistry in a number of den-tal schools in Europe. An attempt has beenmade to represent southern, northern,western, and eastern approaches to train-i ng in the field.

University of MadridProf. Javier Garcia Barbero, Spain

The teaching of conservative dentistry inSpain includes: dental pathology anddental therapeutics relevant to operativedentistry and endodontics, together withthe study of all relevant dental materialsscience.

The general objectives are (1) to studyall diseases affecting teeth with regard toetiology, pathogeneses, clinical manifesta-tions, diagnosis, and prognosis, and (2) toaccurately perform operative dentistry andendodontic treatments to the following lev-els: knowledge and handling of the nec-essary instruments, cavity preparation foramalgam and composite resins accordingto Black classification, cavity restorationwith amalgam and composite resin, es-thetic restorations, and the endodontictreatment of single- and multirooted teeth.

Minimum requirements are (1) preclini-cal-16 amalgam and 12 composite resinposterior restorations and 16 anterior com-posite resin restorations, and (2) clinical-12 amalgam and 25 composite resinrestorations. Treatment distribution in clin-ical studies is variable depending on eachpatient's needs. Patients are allocated tostudents by a central, computerized re-ception service.

Curriculum time requirements are (1)preclinical-70 hours on typodont and ex-tracted teeth, comprising 40 hours for op-erative dentistry and 30 hours for en-dodontics, and (2) clinical-100 hours,comprising 70 hours for operative den-tistry and 30 hours for endodontics.

The student-to-professor ratio is 1:12 inpreclinics and 1:6 in clinics. Following suc-cessful completion of this training, stu-dents enter integrated clinics in whichrestorations and endodontics are per-formed on patients as part of integratedcare. Inlay/onlay treatments, porcelainveneers, post and core buildups, and com-plex endodontics, including endodonticsurgery, are taught in the pregraduationpractical course.

UK Dental SchoolsProf. Nairn H. F. Wilson, Manchester

Traditionally, the teaching of conservativedentistry in the UK has included the teach-ing of operative dentistry, endodontology,and fixed prosthodontics. Subsequent tothe regulatory recognition of dental spe-cialties, including endodontics and fixedand removable prosthodontics in 1998, anumber of dental schools have instituted,or at least planned, internal reconfigura-tions to give endodontology a separateacademic identity and to integrate theteaching of fixed and removable prostho-dontics. Long-established departments ofconservative dentistry have, as a conse-quence, been fragmented and downsizedto departments or academic units ofoperative dentistry, with a number ofschools having given consideration to sub-suming the residual elements of former

251


departments of conservative dentistry intodepartments of, for example, comprehen-sive patient care. Notwithstanding circum-stances in which conservative dentistrycontinues to maintain separate curriculumprovision, typically linked to the core teach-ing of dental biomaterials science, thefuture academic provision for operative, letalone conservative, dentistry as a separatediscipline is increasingly unclear in certainUK schools.

I rrespective of recent and possible fu-ture changes in the provision for theteaching of conservative dentistry in UKdental schools, the teaching of the "drilland fill" philosophy is now being replacedwith preservative approaches to patientcare. As indicated bythe findings of recentsurveys of the teaching of different materi-als and techniques, students in UK dentalschools may be taught the use of mostmodern materials and restorative tech-niques. Traditional forms of teaching,learning, and assessment in conservativedentistry in the UK may increasingly befound to be replaced by competence- andproblem-based approaches to studentprogression. Initiatives in student pairing;skill-mix, involving, in particular, dentalnurses and hygienists; and outreach lon-gitudinal, comprehensive patient care pro-grams are opening up new possibilities forthe efficient, effective delivery of programsof education in conservative dentistry.

Centre for Oral HealthSciences, MalmoDr. Katarina Wretlind, Sweden

At the Centre for Oral Health Sciences inMalmo, cariology for the undergraduatesis taught using the problem-based learn-

ing concept. This begins in the first se-mester and continues throughout thewhole curriculum, including the last (10th)semester. Learning in context, early patientcontact, and a commitment by the stu-dents to take responsibility for their ownlearning are central concepts.

According to the principles of problem-based learning, students acquire knowl-edge of the caries process and how to treatthe disease by solving the problems of thestudy cases presented using specificguidelines. For example, during the thirdsemester, students will be given a case, asfollows: "One of your patients is worriedabout his front teeth. During the last yearbrownish stains, close to the margin of thegingiva, have appeared, and he thinks theyhave a negative impact on his appear-ance." After working with this case the stu-dents should be able to:

Describe how the balance in the oralecosystem can be disturbed and whatthis means for the surface of the toothDescribe the reaction of the tooth ona caries attack and on operative den-tistryUnderstand how caries and its symp-toms can be treated

During the third and fourth semesters,several other cases pertain to cariologyand operative dentistry. Parallel to thetheoretical studies, the students attend thelaboratory during the third semester, thenattend the clinic, treating their ownpatients, during the fourth and fifth se-mesters. Students face clinical tests in di-agnostics and in performing differenttypes of restorations. After the fifth semes-ter, the basic course in cariology is com-pleted, and the students continue to treat

25 2

Conservative Dentistry Training in Europe

patients presenting with caries at theComprehensive Oral Health Care Clinic foradult patients and also later in the clinic forchildren and adolescents.

Munich UniversityProf. Dr. Reinhard Hickel, Germany

lectures on conservative dentistry, includ-ing endodontics and prevention (3 to 4hours), pedodontics (1 hour), and peri-odontics (1 to 2 hours). In the third year(phantom course), the students have spe-cial weekly lectures (2 hours) and seminarsin all aspects of conservative dentistry, in-cluding dental restorative materials.

There are three different levels of regula-tions for dental education in Germany:(1) the federal regulations, (2) universityregulations, and (3) the rules set by thechairmen of the department. This results,i n some cases, in large differences acrossthe 30 dental schools in Germany.

Conservative dentistry includes preven-tive and restorative dentistry, endodontics,pedodontics, and periodontology. For thepurposes of the present comparison, onlyrestorations are considered.

The teaching of direct fillings, includingi nlays and onlays, starts in the third yearwith the preclinical phantom course inconservative dentistry.

The principal teaching in restorativedentistry is in the fourth and fifth year of thecurriculum in which two courses, each ofwhich require 20 hours per week treatingpatients, have to be completed. In the sec-ond clinical course (fifth year), 30 surfacesfor anterior fillings and 30 surfaces (mesio-occlusodistal = 3) of posterior restorationshave to be completed, together with 30surfaces of indirect restorations (inlays). Inthefirst clinical course in conservative den-tistry, 20 rather than 30 surfaces are re-quired. The students have to treat patientsrequiring restorations as part of othertreat-ment needs, including periodontal, en-dodontic, and preventive therapies.

Additionally, the students have to parti-cipate in two 10- to -1 2-week semesters of

I talian Dental SchoolsProf. Dr. Sandro Rengo, Naples

I n Italy, the teaching of operative dentistryis organized as a 3-year course. One yearconcerns endodontics and 2 years ad-dress restorative techniques. The mainaims of the course are:

1. To provide the students with a theoreti-cal knowledge of craniofacial anatomy,physiology, and the basic techniquesand materials used in operative den-tistry

2. To have the students acquire an under-standing of and basic skills in the han-dling of instruments and materials,together with knowledge of guidelinesfor ergonomic work organization priorto treating patients.

I n each yearthe teaching consists of tra-ditional lectures ex cathedra and seminarswith an emphasis on new materials, in-struments, and clinical procedures. Thistraining consists of cavity preparations foramalgam, direct and indirect composites,and endodontic therapy, first on simulatorsand extracted teeth and subsequently inpatients (while under supervision). At theend of the course, the students have to takean examination that consists of a written pa-per, a clinical test, and an oral examination.

253


Nijmegen UniversityProf. Dr. Alphons J. M. Plasschaert, TheNetherlands

The dental curriculum at NijmegenUniversity is a 5-year program. Conserv-ative dentistry (defined here as operativedentistry limited to the techniques and the-ory to restore teeth with plastic filling ma-terials) is taught in each consecutive year.The curriculum is programmed to a totalstudy load (SL) of 1680 hours (contactti me and self-study time) per year. In thefirst year there is a course entitled"Restoration of Teeth" with an SL of 320hours (142 hours contact time: 126 hourspractice and 16 hours theory). The objec-tive of this course is to complete simplepreparations and restorations. The courseentitled "Teeth" has for conservative den-tistry a 24-hour SL, of which 4 hours is con-tact time. In the second yearthere is a 240-hourSL in the course "Restoration of TeethI I " ( 203 hours contact time: 190 hourspracticals and 13 hours theory).

I n the third, fourth, and fifth year, con-servative dentistry is integrated with otherclinical activities, including periodontics,endodontics, crown and bridge work, andapplied preventive dentistry. The three in-tegrated clinical courses have SLs of 160,160, and 800 hours. In addition, there isan elective course in the fifth year onadhesive/cosmetic dentistry comprising160 hours. The minimal requirements interms of numbers of surfaces to be com-pleted are: second year, 11; third year, 36;fourth year, 60. There is no quantitative re-quirement in the fifth year. Students haveto complete several patient cases in whichconservative procedures are part of thetreatment plan.

Discussion

The present is the result of the past, andthe future lies in today. It is obvious fromthe data presented here that there aremarked differences among dental schoolsi n Europe in relation to the teaching ofconservative dentistry as part of the dentalcurriculum. It is promising, however, that inrecent times information exchange andstudent and staff mobility schemes havecontributed to some harmonization of theteaching of conservative dentistry acrossEurope. The DentEd site visitation pro-gram is unique and will certainly con-tribute to a greater commonality inapproach and quality.

We are at the beginning of a new cen-tury and millennium. If progress continuesat the pace seen in the last century, it ishard to envisage what innovations in com-puter science and technology alone will dofor data processing and communications.Flexibility and a readiness to change isessential in having dentists become life-long learners, giving the best they can toserve their patients. A challenge will be thesharing of creativity and the pooling of re-sources in a combined effort to developCD-ROM educational programs for con-servative dentistry at the European level. Itis, therefore, essential to first agree on pan-European learning objectives for conser-vative dentistry. Questions as to what kindof professionals we need in dentistry in thefuture, the changing role of the practition-er, and the impact dental auxiliaries willhave on the future delivery of operativedental care are to be researched anddebated. In this way, it is hoped that abetter understanding will be promotedamong teachers of conservative dentistryacross Europe. Organizations, including

254

References

the AODES, will hopefully provide a forum

3. Fusayama T. A Simple Pain-Free Adhesive

for future collaborations and cooperation. Restorative System by Minimal Reduction andTotal Etching. Tokyo: Ishiyaka Euroamerica,1993.

References

4. Robertson TH. Introduction to operative den-tistry. In: Sturdevant CM, Bartons RE, Sockwell

CL, Strickland WD (eds). The Art of Operative1. European Economic Community. Free move-

Dentistry, ed 2. St. Louis: Mosby, 1985.ment and the mutual recognition of diplomas of

5. Wilson NHF, Mjor IA. The teaching of Class I anddental practitioners [directive 78/687/EEC].

Class II direct composite restorations inBrussels: European Economic Community,

European dental schools. J Dent 2000;28:1978.

1 5-21.2 European Union. Clinical proficiencies required

for the practice of dentistry in the EuropeanUnion [directive XV/E/8316/2/93-EN]. Brussels:European Union, 1994.

255

I ndex

Page numbers followed by 'f' indicate figures;those followed by "t" indicate tables.

AAcademy of Operative Dentistry, European

Section, 249Acid etching

dentin, 28, 30f, 73, 75f-76fenamel, 73, 75f, 147, 165, 177, 180f, 230fporcelain, 233smear layer, 73, 75f-76f, 88

Acrylic mock-up, 140, 141f, 142Adhesive cements and systems

advancements in, 61benefits of, 242caries prevention using, 225dentinal bonding, 30f-31fevaluation of, 33indirect restorations, 96-97, 103, 104f-105fproperties of, 97tresins. See Composite resins.self-etching, 29, 32-33, 32ftooth preservation benefits of, 79types of, 97t

Aging. See Elderly.Amalgam restorations

Black's technique, 242, 243fdegradation of, 197properties of, 73

Anterior restorationscase study examples of, 57, 58f-60f, 69f-70fcolor matching, 61, 62f-70festhetic principles for, 61-62, 62f-70flayering technique for, 64f-67fmargin placement, 110, 111fmaterials development, 57, 61retraction cord placement, 126f, 129tooth preparations

errors in, 109-110extent of, 121taper of, 110, 111f

tooth reduction assessmentsdepth cuts, 112, 112fmatrices, 112, 112f

provisional crown, 112-113, 113fworn teeth

axial movement, 115-116, 117fchanges resulting from, 113-114composite resin restorations of, 116, 117fcrown lengthening, 114-115description of, 113ill ustration of, 123focclusal adjustments for, 114space creation methods for, 114-116vertical dimension of occlusion increases, 115

Anterior teethaxial movement of, 115-116, 117fcolor of, 62fcoronal and radicular dentin, 193curvature of, 110endodontically treated, bonded partial restorations

for, 199, 200f-201fextrusion of, 120facial aspects of, 110preparations of

diagnostic waxup, 140, 142errors in, 109-110extent of, 121i mportance, 135taper of, 110, 111f

restorations of. See Anterior restorations.rubber dam placement, 44wear of. See Anterior restorations, worn teeth.

Antimicrobial varnishes, 224, 224tAxial movement of anterior teeth, 115-116, 11 7f

BBacteria

removal of, 17-18, 18troot surface caries caused by, 223t, 223-224

Bevel, esthetic uses of, 61, 68f

Biologic widthcrown-lengthening surgery, 52, 53f-54fi ndirect restorations, 119

Biomimetics, 135-136Bonded partial restorations, for endodontically

treated teethadvantages of, 193-197

25 7

I ndex

anteriorteeth, 199, 200f-201f

biomechanical properties of, 195, 197definition of, 191fracture resistance benefits, 197

full-coverage restorations vs, 195i n immature teeth, 195i mmediate placement of, 196fi ndications, 197-199posterior teeth, 199, 202f-206f, 203transitional, 195

Bondingadhesive systems, 29, 32-33, 32fcementum, 98ceramics, 165-166chemical irritation during, 29composite resins, 166dentin. See Dentin.enamel, 98

etching benefits for, 73. See also Acid etching.evaluations of, 29micromechanical, 73, 77fsubstrates for, 98-100, 99f-101f

Bonding agents and systemscolor of, 63dentinal damage reduced using, 18testhetic principles for applying, 63etching benefits of, 73, 75fpulpal damage prevented using, 25resin. See Composite resins.restoration protection using, 20t

Burs, 143f, 144

CCAD/CAM system

Cerec 3. See Cerec 3 CAD/CAM system.description of, 102-103

Calcium-hydroxide cements, 18tCaries

age-related increases in, 216crown margin placement and, 50i n elderly, 216root

antimicrobial varnishes, 224, 224tbacterial pathogens associated with, 223t,

223-224noninvasive therapy, 224-227prevention of, 224-227restorative materials for, 227treatment planning algorithm, 226f

tissue loss secondary to, 191Caries detector, 79, 81f

Cementation, temporary, 145Cementoenamel junction, 98, 101f-102fCements

calcium-hydroxide, 18tglass-ionomer. See Glass-ionomer cements.l uting. See Luting cement.nonadhesive, 98, 98t

Cementum bonding, 98Ceramic restorations

acrylic mockup, 140, 141f, 142bonding, 165-166case study example of, 149, 150fcasting of, 102description of, 135i ndications, 136, 137f-138fmilling of, 102

properties of, 96, 145-146provisional restoration, 142, 144tooth preparations, 142, 143f, 144, 147tooth structure losses, 142waxups, 140f, 140, 142

Ceramic veneerbonding of, 148-149

case study example of, 149, 150fCerec 3 CAD/CAM system design of. See

Cerec 3 CAD/CAM system.chip fractures of, 146delamination of, 146

enamel and, similarities between, 145-146failure of, 146i ndications, 136, 137f-139focclusal adjustments, 149placement of, 148-149production of, 146surface conditioning, 147, 148f, 166

tooth preparations for bonding, 147t ry-in, 146-147

Cerec 3 CAD/CAM system

background, 154clinical preparations

impressions, 155provisional restoration, 155tooth preparations, 155, 156f

shade selection, 154system description, 153veneer

adhesive placement of, 162, 163fCAD design of, 156f-159f, 156-159cast try-on, 159, 161festhetic buildup, 159, 159f-161f

Cervical chamfer, 142, 155, 156f

258

I ndex

Chip fractures, 146Chlorhexidine, 225Clamps, rubber dam, 40t, 40-41, 41f-43fCollagen fiber network, 77fCompomers

advantages of, 97tdisadvantages of, 97thydrophilicity of, 35margin protection, 19trubber dam use, 35

Composite resinsadvancements in, 73, 96advantages of, 97tadverse reactions, 79bonding to, 166color of, 61dentin interface with, 73, 77f-78fdisadvantages of, 73, 74f, 97thybrid layer, 73, 77f, 88l ight curing of, 79, 81, 82f-83f, 146opacities of, 61polymerization shrinkage, 79, 89-90posterior teeth placement. See Composite-up

technique.prevalence of use, 242-243, 244tproperties of, 97t, 146self-curing, 89, 92tags, 78f, 100

Composite-up technique, for direct posteriorrestorations

adhesion procedures, 88-89biocompatibility, 88-89cavity preparation, 88finishing of, 91f, 92i ndications, 88occlusal surface, 90f-91f, 92polymerization shrinkage considerations, 89, 92proximal surface reconstruction, 89, 89f

Conservative dentistryadhesive techniques, 242composite restorations, 242-243, 244fcontent changes in, 241-243disclosing solutions, 241-243education in, 246-249, 250tEuropean developments in, 248-249, 250tfuture of, 254-255occlusal width, 243, 245ftraining programs, 251-254

Crown lengtheningbiologic width after, 52, 53f-54f

cosmetic effects of, 115, 11 6f

i ndications, 120partial-thickness flap, 52f-53f

subgingival caries, 50technique for, 50, 52, 52f, 123fworn teeth, 114-115

Crown marginscaries incidence, 50description of, 49periodontal support loss, 49-50subgingival vs supragingival placement, 49-50

DDam. See Rubber dam.Delamination, of ceramic veneers, 146Dental apoptosis cycle, 193DentEd Consortium, 249, 250tDentin

adhesive bonding to, 29, 30f-32fage-related changes in, 230anatomy of, 27-28bacteria removal from, 17-18, 18tbonding agents, 145, 165caries preparation effects, 28composite resin interface with, 73, 77f-78fcoronal and radicular, in anterior vs posterior

teeth, 193damage to, 17-19definition of, 17demineralization of, 25, 225disinfection of, 17, 18tenamel and, relationship between, 135-136etching of, 28, 30f, 73, 75f-76ffractured, 76f-77fhybridization of, 28, 29, 98, 100fhybrid layer, 73, 77f, 88permeability of, 18, 28, 33properties of, 28sclerotic, 230smear layer removal, 73, 75f-76f, 88types of, 98, 99fi n vital vs nonvital teeth, 195

Dentinal tubulesdescription of, 27-28i ll ustration of, 74fresin penetration into, 230

Dentin-enamel bonding systemsdentinal damage reduced using, 18tpulpal damage prevented using, 25restoration protection using, 20t

Dentition. See Teeth.Depth cuts, 112

25 9

I ndex

Diagnostic waxup. See Waxup.Diastema, 145Direct restorations

composite-up technique. See Composite-uptechnique.

i ndirect vs, 95

posterior teeth. See Posterior teeth restorations.Disclosing solutions, 241-243

EElderly

caries, 216, 223-227dental attendance visits by, 217-218dentinal changes, 230enamel changes, 229-230fractured teeth, management options for

all-porcelain restoration, 231, 232fcast metal restoration, 231, 232fdescription of, 231porcelain4used-to-metal restoration, 231, 232fsurface treatments, 231, 233, 234f

masticatory reductions in, 218-219nutrition, 218-219oral anatomy changes in

salivary glands, 213-215, 214fsoft tissue, 213, 215

oral health ofbehaviors associated with, 217-218contemporary changes in, 211, 213dentate, 214f, 215-216

oral hygiene practices, 218periodontal disease, 216-217population projections for, 211-213, 212f, 214fstereotypes, 211taste perception changes, 215tooth wear. See Worn teeth.

Enamelage-related changes in, 229-230bonding to, 98dentin and, relationship between, 135-136etching of, 73, 75f, 147, 165, 177, 180f, 230fresidual, effect on restoration margin, 103waxups for preserving, 144

Enamel marginalteration prevention methods, 21, 22f-23fbeveling of, 61, 68fcementoenamel junction, 98, 101f-102fpreservation of, 61

Endodontically treated teethbonded partial restorations

advantages of, 193-197

anterior teeth, 199, 200f-201 fbiomechanical properties of, 195, 197definition of, 191fracture resistance benefits, 197full-coverage restorations vs, 195i n immature teeth, 195i mmediate placement of, 196fi ndications, 197-199posterior teeth, 199, 202f-206f, 203transitional, 195

description of, 191failure of restorations, 195fragility of, 191post and core restorations for, 191-193, 192ftreatment planning considerations, 191

Etching. See Acid etching.

FForceps, rubber dam, 39-40, 40fFractured teeth, management options for

all-porcelain restoration, 231, 232fcast metal restoration, 231, 232fdescription of, 231porcelain-fused-to-metal restoration, 231, 232fsurface treatments, 231, 233, 234f

GGingiva

contours of, 120retraction cord for crevice dilation, 126f, 129, 176f

Gingival index, 49Glass, 96Glass-ionomer cements

advantages of, 97tantibacterial benefits of, 24-25disadvantages of, 97tfluoride-releasing benefits of, 21margin protection, 19t-20t, 21resin-modified, 97t

I ndirect inlays, 170, 170f-173fI ndirect restorations

anterior teethadhesive technique, 103, 104f-105fbiologic width, 119bonding, 98-100, 99f-102f, 121-122case study example of, 122-131cementing materials for, 96-98, 97t-98tconstruction techniques, 100-103dentoperiodontal relationships in, 119-131

260

direct restorations vs, 95esthetic materials for, 95-96patient management, 119, 120fperiodontal treatment and, 119-121quality of, 103

posterior teethinlays. See Inlays.l ongevity of, 185, 186tonlays. See Onlays.rationale for, 166technique for, 174-185, 175f-185f

I nlayschairside, 167-170direct composite, 167extraoral composite, 167-170i ndirect, 170, 170f-173fl ongevity of, 185, 186tprovisional, 174, 177, 178fsemidirect technique for, 166-167technique for, 174-185, 175f-185f

I ntercuspal position, 114

LLight curing, of composite resins, 79, 81, 82f-83f,

146, 182fLuting cement

i nlays, 177, 181frestoration seating, 97

temporary, for provisional restorations, 145

MMandibular molars, 81, 83, 83f-84fMargin of restoration

alterations prevention, 24-25

chemical degradation of, 20gaps, 18-19, 22fhybrid layer, 22f-23fmicroleakage, 20-21, 74f, 95, 103, 195

Masticatory function, in elderlynutrition and, 218-219reductions in, 218

Materials. See specific material.Matrices, for tooth reduction assessments, 112,

112fMetal matrix, 89Microleakage, 20-21, 74f, 95, 103, 195Moisture management

description of, 35rubber dam. See Rubber dam.

Mutans streptococci, 223t, 224

NNatural inlay, 96Nonadhesive cements, 98, 98t

Occlusionadjustments

ceramic veneer placement, 149i nlay placement, 177, 182f-183fspace for anterior restorations, 115

vertical dimension of, 115, 233, 235fOnlays

i ndirect, 170, 170f-173flongevity of, 185, 186ttechnique for, 174-185, 175f-185f

Oral mucosa, age-related changes in, 215

PPartial restorations, for endodontically treated

teethadvantages of, 193-197anterior teeth, 199, 200f-201fbiomechanical properties of, 195, 197definition of, 191fracture resistance benefits, 197full-coverage restorations vs, 195in immature teeth, 195immediate placement of, 196findications, 197-199posterior teeth, 199, 202f-206f, 203transitional, 195

Periodontal disease, 216-217Periodontal tissue

atraumatic manipulation of, 49, 51fin elderly, 216-217restoration-induced trauma, 49, 50f

Polishing, 184f-185fPolymerization shrinkage, 73, 74f, 79, 89Porcelain

acid etching of, 233anterior tooth wear restored using, 237, 238fcharacteristics of, 95-96

Porcelain-fused-to-metal restorationfor fractured teeth, 231, 232ffor tooth wear, 236, 237f

Porcelain veneer. See also Ceramic veneer.composite accumulation under, 142i l l ustration of, 138f

Post and core restorations, 191-193, 192f

I ndex

261

I ndex

Posterior teeth restorationsadhesion procedures, 88-89biocompatibility, 88-89bonded partial restorations, for endodontically

treated teeth, 199, 202f-206f, 203bonding

restorative materials, 165-166tooth substrates, 165

cavity preparation, 88coronal and radicular dentin considerations, 193finishing of, 91f, 92i ndications, 88i ndirect

inlays. See Inlays.longevity of, 185, 186tonlays. See Onlays.rationale for, 166technique for, 174-185, 175f-185f

mandibularfirst molar, 81, 83, 83f-84focclusal surface, 90f-91f, 92phases of, 87polymerization shrinkage considerations, 89, 92proximal surface reconstruction, 89, 89ftechnique for, 79, 81, 83, 80f-84f

Provisional restorationcase study use of, 122, 125fi nlays, 174, 177, 178flayering techniques for, 145leakage of, 195principles of, 142, 144production of, 145tooth reduction assessments using, 112-113,

113fPulp

anatomy of, 27-28damage, 24-25vascular supply, 28

Pulp-dentin complexadhesive systems, 29, 30f-32fi mmediate dentinal bonding for preservation of,

145protection of, 28-37

RResin composites. See Composite resins.Resin tags, 78f, 100

Restorationsamalgam. See Amalgam restorations.anterior teeth. See Anterior restorations.ceramic. See Ceramic restorations.

262

external protection of, 19, 19ti nternal protection of, 19-21margin. See Margin of restoration.marginal gaps, 19-21, 22fpartial. See Bonded partial restorations.periodontal tissue trauma caused by, 49, 50fpost and core, 191-193, 192fposterior teeth. See Posterior teeth restorations.provisional. See Provisional restoration.resin luting cement for seating of, 97

Retraction cordcervical chamfer created using, 142gingival crevice dilation using, 126f, 129, 176f

Retruded axis, 114Rubber dam

advantages of, 36tadverse reactions to, 37anterior teeth use, 44application technique, 44-45, 45f-46fclamps, 40t, 40-41, 41f-43fcolors of, 36-37forceps, 39-40, 40fframe, 37, 38fhistory of, 35placement of, 44-45, 45f-46fposterior teeth use, 44powder-free, 37preparations for application, 41, 44prerequisites for using, 36punch, 37-39, 38f-39fremoval of, 47fsummary overview of, 48thickness of, 36, 36t

Salivary glands, age-related changes in, 213-215,214f

Sealers, 19tSelf-etching adhesive systems, for dentinal

bonding, 29, 32-33, 32fSilane, 177Silanization, 165Smear layer, 73, 75f-76f, 88

TTeeth

cracks in, 197i n elderly, 214f, 215-216fractured. See Fractured teeth.preparing of. See Tooth preparations.

I ndex

structure loss

bonded partial restoration indications,198-199,203

ceramic restorations, 142effects of, 195

Toothpastes, 19tTooth preparations

diagnostic waxup, 140, 142errors in, 109-110extent of, 121i ll ustration of, 143fi mportance, 135principles of, 142, 143f, 144taper of, 110, 111f

Tooth wear. See Worn teeth.

VVeneers

ceramic. See Ceramic veneer.Cerec 3 CAD/CAM design of, 156f-159f,

156-159Vertical dimension of occlusion, 115, 233, 235f

WWaxup

additive, 140, 140f, 142ceramic restorations, 140, 142enamel preservation, 144indirect restorations, 122, 124f

Worn teethanterior

axial movement, 115-116, 117fchanges resulting from, 113-114composite resin restorations of, 116, 117fcrown lengthening, 114-115description of, 113ill ustration of, 123focclusal adjustments for, 114porcelain additions, 236, 238fporcelain-fused-to-metal restoration for, 236,

237fspace creation methods for, 114-116vertical dimension of occlusion increases, 115

attritive pattern, 233, 235fcauses of, 233composite resins for

i ndications, 233laboratory-made restorations utilizing, 236,236f-238f

erosive, 233, 235f

XXerostomia, 213, 215

Advances in Operative Dentistry Roulet Vol 1 2001.pdf

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