The Effect of Differ the effect of different surface treatments on retention of glass fiber posts ,...

THE EFFECT OF DIFFERENT SURFACE TREATMENTS ON RETENTION OF GLASS FIBER POSTS, CARBON FIBER POSTS AND CAST METAL POSTS. AN IN-VITRO STUDY

By Dr. ROMESH SONI

Dissertation submitted to

Rajiv Gandhi University of Health Sciences, Bangalore

In partial fulfillment of the requirements for the degree of

MASTER OF DENTAL SURGERY

in

PROSTHODONTICS, CROWN&BRIDGE INCLUDING IMPLANTOLOGY

Under guidance of

Prof Dr. D. R. PRITHVIRAJ

DEPARTMENT OF PROSTHODONTICS,

GOVERNMENT DENTAL COLLEGE AND RESEARCH

INSTITUTE

BANGALORE-02

(2006-2009)

I

RAJIV GANDHI UNIVERSITY OF

HEALTH SCIENCES, BANGALORE KARNATAKA

DECLARATION BY THE CANDIDATE

I hereby declare that the dissertation/thesis entitled ‘‘THE EFFECT OF

DIFFERENT SURFACE TREATMENTS ON RETENTION OF

GLASS FIBER POSTS, CARBON FIBER POSTS AND CAST

METAL POSTS. AN IN-VITRO STUDY” is a bonafide work carried out by

me under the guidance of Dr.D.R.PRITHVIRAJ, Professor and Head,

Department of Prosthodontics, Government Dental College and Research Institute,

Bangalore.

Date:

Place: Bangalore Dr. ROMESH SONI

II

RAJIV GANDHI UNIVERSITY OF

HEALTH SCIENCES, BANGALORE KARNATAKA

CERTIFICATE BY THE GUIDE

This is to certify that this dissertation entitled “THE EFFECT OF



METAL POSTS. AN IN-VITRO STUDY” is a bonafide research work done

by Dr. ROMESH SONI in partial fulfillment of the requirement for the degree of

MASTER OF DENTAL SURGERY DEGREE IN

PROSTHODONTICS.

Date: Dr. D. R. PRITHVIRAJ, M.D.S

Place: Bangalore Professor& Head

Dept of Prosthodontics

Govt Dental College and Research Institute

Bangalore -02

III

ENDORSEMENT BY THE HOD,

DIRECTOR/HEAD OF THE INSTITUTION

This is to certify that this dissertation entitled “THE EFFECT OF



METAL POSTS. AN IN-VITRO STUDY” is a bonafide research work done

by Dr. ROMESH SONI under the guidance of Dr. D. R. PRITHVIRAJ,

Professor and Head, Department of Prosthodontics, Government Dental College and

Research Institute, Bangalore.

(Dr.D.R.Prithviraj) (Dr. S.S. Hiremath) Professor& Head Dean cum Director

Dept of Prosthodontics Government Dental College and

Research Institute, Bangalore.

Date: Date:

Place: Bangalore Place: Bangalore

IV

V

COPY RIGHT

Declaration by the Candidate

I hereby declare that the Rajiv Gandhi University of Health Sciences,

Bangalore, Karnataka shall have the rights to preserve, use and

disseminate this dissertation/thesis in print or electronic format for

academic/research purpose.

Date: Place: Bangalore Dr. ROMESH SONI

© Rajiv Gandhi University of Health Sciences, Karnataka

VI

ACKNOWLEDGEMENTS This dissertation has been one of the most significant academic challenges I

have ever had to face. Without the constant support, guidance and encouragement of

the following people, this study would not have been completed. It is to them I owe

my deepest gratitude.

It is my privilege and honor to express my sincere thanks and gratitude to

Dr. D. R. Prithviraj, Professor and Head, Department of Prosthodontics,

Government Dental College and Research Institute, Bangalore, for his continuous

support, guidance provided and constant encouragement shown to me. His wisdom,

knowledge, vision and commitment to highest standards inspired and motivated me in

shaping my outlook to this profession.

I avail this opportunity to thank Dr. Sounderraj, Professor, Dr. Prema,

Assistant Professor and Dr.Vishwanath, Assistant Professor, Department of

Prosthodontics, for their constant guidance and valuable suggestions during the course

of my study.

I am thankful to Dr S.S. Hiremath, Dean cum Director, Government Dental

College and Research Institute, Bangalore for providing the facilities needed for this

study.

I express my heartfelt thanks to Dr. Kalavathi, Dr. Anoop, Dr Nagaranjni,

Dr Reshma, lecturers, Department of Prosthodontics for their suggestions and co-

operation during my post-graduate study.

VII

I am also thankful to all the non-teaching staff and technicians in the

Department of Prosthodontics for their support and co-operation during the course of

my study.

I would like to thank Mr Rajesh, Manager, 3M ESPE, Bangalore who

allowed me to analyze my samples in their universal testing machine. My sincere

regards to Mr.Tejasvi, senior statistician for his help in preparing the statistical data

needed for this study.

My profound thanks and appreciation to my seniors Dr. Sarvan, Dr. Ankit

and Dr. Vishal, and to my colleague Dr. Sushma for their untiring stint of moral

support, encouragement, and help. I sincerely thank Dr. Sumit, Dr. Anish, Dr. Pooja

and Dr. Malesh for their constant help and support.

I thank my parents Mr. D.S. Soni & Mrs. Narender Kaur and my loving

brother Dr. Ankit Soni who has always supported, encouraged and believed me in all

my endeavors. At last but not the least, my wife Dr. Shilpa Soni whose belief in me

and my capabilities has encouraged and motivated me a lot.

Ultimately I thank the Almighty for his blessings and being besides me

through the thick and thin of life.

Date:

Place: Bangalore Dr.ROMESH SONI

.

VIII

LIST OF ABBREVIATIONS USED

ANOVA: Analysis of Variance

cm: Centimeter

EDTA: Ethylene diamene tertraacetic acid

FRC: Fiber reinforced composite

Kgf : Kilogram force

mm: Millimeter

PMMA: poly- methyl methacrylate

SD: Standard Deviation

SEM: Scanning electron microscope

IX

ABSTRACT Background and objectives: The present study was conducted with the purpose of

analysis of the effect of different surface treatments on retention of glass fiber posts,

carbon fiber posts and cast metal posts.

Method: Ninety extracted single rooted human teeth were selected. Each tooth was

cut with, a diamond rotatory cutting instrument, 1 mm coronal to the cemento-enamel

junction. Post spaces were prepared to 9mm in length for all the teeth with the specific

drill bit provided by the manufacturer for the specific size of post. Surface treatment

of the glass fiber post, carbon fiber post and cast metal posts with ethyl alcohol, resin

primer and air-borne alumina particle abrasion was done. Posts were luted with dual

cure resin cement. For the Retentive force test, a screw driven universal testing

machine was used to apply tensile load to the post. The force required to dislodge

each post from prepared post space was recorded.

Results: Air-borne alumina particle abraded cast-metal posts had the highest retentive

strength compared to all other surface treated or untreated posts used in the study

followed by primer treated cast metal posts and ethyl alcohol treated cast metal posts.

Airborne alumina particle abraded glass fiber posts and carbon fiber posts had the

next highest retentive strengths. Treating the surface of the posts with resin-primer

and ethyl alcohol produced no statistically significant difference in the retentive

strength of all the type of posts used in the study. There was no significant difference

in the retentive strength obtained between glass fiber posts and carbon fiber posts.

X

Conclusion: Within limitations of this study, it may be concluded that, air-borne

alumina particle abrasion increased the retentive strength of all the type of posts used

in this study. Surface treatment of the posts with resin-primer and ethyl alcohol

produced no statistically significant difference in the retentive strength.

Keywords: Retentive strength, Surface treatment, Airborne alumina particle abrasion,

Tensile load.

XI

CONTENTS

1. INTRODUCTION 1-2

2. OBJECTIVES 3

3. REVIEW OF LITERATURE 4-14

4. METHODOLOGY 15-25

5. RESULTS 26-37

6. DISCUSSION 38-42

7. CONCLUSION 43

8. SUMMARY 44

9. BIBILIOGRAPHY 45-47

XII

LIST OF TABLES

Sl. No

Tables

Page no

I Retentive strength of carbon fiber post treated with ethyl alcohol

28

II

Retentive strength of carbon fiber post treated with resin primer

28-29

III

Retentive strength of carbon fiber post air abraded with alumina

29-30

IV

Retentive strength of glass fiber post treated with ethyl alcohol

30

V

Retentive strength of glass fiber post treated with resin primer

30-31

VI

Retentive strength of glass fiber post air abraded with alumina

31-32

VII Retentive strength of cast metal post treated with ethyl alcohol

32

VIII Retentive strength of cast metal post treated with resin primer

32-33

IX

Retentive strength of cast metal post air abraded with alumina

33-34

X Means and standard deviations of each group

34

XI

Comparisons of the mean retentive strength of posts using ANOVA test.

34-35

XII

Multiple comparisons using Bonferroni method to find out

significant difference between type of post

35

XIII

Multiple comparisons using Bonferroni method to find out

significant difference between type of treatment.

36

XIII

LIST OF FIGURES

Sl. No

Figures

Page No

1

Armamentarium used for the study

20

2

Custom made device of stainless steel (lateral view)

20

3

Custom made device of stainless steel (superior view)

21

4

PMMA Blocks with sectioned teeth and prepared post

spaces

21

5a

Carbon fiber post luted with dual cure resin cement

22

5b

Glass fiber post luted with dual cure resin cement

22

5c

Cast metal post luted with dual cure resin cement

23

6

Induction Casting Machine

23

7

Universal Testing Machine

24

8a

Universal Testing Machine with the custom made device

24

8b

Universal Testing Machine with the dislodged post

25

XIV

LIST OF GRAPHS

Sl. No.

Graphs

Page no.

I.

Mean retentive strength of each group in bar diagram

36

II.

Main effects plot of retentive strength of each group

37

III.

Interaction plot of retentive strength between each group

37

Introduction

Restoring endodontically treated teeth is a challenge when insufficient coronal

tooth structure remains to support a restoration, and the post is commonly used to

retain the core. Post and core systems have been used to restore endodontically treated

tooth for more than 250 years.1

Post and core system are available in variety of materials. Cast metal post and

core foundations have a long history of successful use due to their superior physical

properties. However, esthetic properties of these materials are limited since gray

colored post and core is apparent when used to support translucent all-ceramic

restorations. Coupled with a high lip line, cast metal post and core foundations may

result in esthetic problems. Additionally, their high elastic modulus can cause stress

concentration within surrounding radicular dentin, resulting in root fractures.2

Prefabricated post systems are also popular because they can provide satisfactory

results, while saving time and reducing costs. However, prefabricated post should

adequately adapt to prepared root canal otherwise a cast post and core should be used.

Carbon fiber posts have also come into use for prosthodontic applications.3 In

general, the mechanical properties of a fiber reinforced composite material depend

strongly on load direction. The fatigue behavior of fiber reinforced composites which

are anisotropic is also vastly different from that of homogenous materials. In a

homogenous material under fatigue, a crack once initiated, often propagates quickly,

thus leading to sudden failure of the material. However, the damage process in

composite materials is complex, consisting of matrix cracking, interface debonding,

delamination, local fiber breakage and the microstructure of the material has a great

1

Introduction

influence on fatigue behavior. Further, properties such as biocompatibility and

corrosion resistance, make the carbon fiber post a potential replacement for

conventional metallic post in many clinical situations. However, the modulus of

elasticity of carbon fiber post is much greater than that of dentin. Also as with

metallic posts, the use of carbon fiber posts have generally limited esthetic

expectations. Their dark underlying color can adversely influence the shade of

overlying gingival tissue and prosthetic restorations.4 Post made up of tooth colored material such as glass fibers have become

popular because they increase the transmission of light within root and overlying

gingival tissues. Glass fiber posts are composed of glass fibers, inorganic filler, and a

resin matrix. The low modulus of elasticity of fiber reinforced epoxy resin post has

been reported to reduce risk of root fracture. In addition, the restoration of

endodontically treated teeth with metal free materials eliminates the potential hazards

of corrosion and hypersensitivity. Fiber reinforced posts also have advantage of easy

removal if endodontic retreatment is required.5

Many in-vitro studies have investigated various factors that affect retention of

a post. However, very few studies have been done to evaluate the effect of different

surface treatment on retention of Glass fiber post, Carbon fiber post and Cast metal

posts. Hence, this study was carried out to compare the effect of surface treatment

with ethyl alcohol, resin primer and air-borne alumina particle abrasion on the

retention of Glass fiber post, Carbon fiber post and Cast metal posts.

2

objectives

The objectives of this study are as follows-

1. To evaluate the effect of surface treatment by 57.1% Ethyl alcohol on

retention of glass fiber posts.

2. To evaluate the effect of surface treatment by Rely a Bond Resin Primer on

retention of glass fiber posts.

3. To evaluate the effect of surface treatment by Air borne Alumina Particle

Abrasion on retention of glass fiber posts.

4. To evaluate the effect of surface treatment by 57.1% Ethyl alcohol on

retention of carbon fiber posts.


retention of carbon fiber posts.

6. To evaluate the effect of surface treatment by Air borne Alumina Particle

Abrasion on retention of carbon fiber posts.

7. To evaluate the effect of surface treatment by 57.1 % Ethyl alcohol on

retention of cast metal posts.


retention of cast metal posts.

9. To evaluate the effect of surface treatment by Air Borne Alumina Particle

Abrasion on retention of cast metal posts.

10. To compare the effect of surface treatment by 57.1 % Ethyl alcohol, Rely a

Bond Resin primer and Air borne Alumina Particle Abrasion on retention of

glass fiber post, carbon fiber post and cast metal post.

3

Review of literature

Studies have been conducted to know the effect of different surface treatments

on the retentive strength of the different types of posts. Different materials and

methodologies have been tried by different authors to improve the retentive strength.

The related articles have been reviewed and presented here.

The authors6 in 1993 conducted a study to evaluate the effect of Ethylene

diamine tetraacetic acid (EDTA) in the post spaces. They concluded that EDTA was

too strong a solvent to remove the smear layer even for limited periods. The inorganic

smear layer may be removed but the adjacent dentin of the canal may also be

appreciably weakened by the EDTA because of deterioration of the inorganic matrix

of dentin.

The authors7 in 1994 conducted a study to evaluate the retention of posts

cemented with various dentinal bonding cements. The study compared the ability of

three resinous cement and a glass ionomer cement to retain the post in the root canals

of extracted endodontically treated maxillary canines. Resinous cements vary in their

ease of manipulation and in their ability to retain endodontic post. Their study

demonstrated that C & B metabond cement provided the greatest retention for the

cemented posts. The glass ionomer cement (Ketac-Cem) was equally or more

retentive than Panavia and All bond 2 resinous cement, respectively. Ketac-Cem

cement was also easier to manipulate.

The authors8 in 1995 conducted a study to evaluate the survival rate and

4


failure rate of two post designs – custom cast tapered posts and parallel sided serrated

posts. The result of the study showed loss of retention being the most frequent cause

of failure for both type of post, the incidence being higher for custom cast tapered

post.

The authors9 in 1997 conducted a study to evaluate the effect of different

surface textures on the retentive strength of tapered posts. Two sizes of tapered

titanium post were used: post No.1, 9 mm length, 0.5 mm base diameter; and post No.

3, 15 mm length, 1.1 mm base diameter were used. The various surface textures of the

tapered post used were smooth, smooth with grooves, sandblasted, sandblasted with

grooves. In addition, effect of size of post and roughening the dentinal walls of the

post spaces on retentive strength was also evaluated. They concluded that smooth post

showed the lowest retentive strength. Sandblasting the smooth post doubled its

retentive strength. The retentive strength of both smooth and sandblasted posts could

be further increased by the addition of circumferential grooves. Roughening the

dentinal walls of the prepared post space increased the retentive strength of

sandblasted posts with and without grooves even more. Larger posts demonstrated an

absolute retentive strength almost three to four times higher than smaller size posts.

The authors10 in 1997 conducted a study to evaluate cyclic fatigue testing of 5

endodontic post designs supported by four core materials. This study was examined

the ParaPost, and Volck) with four core materials (Tytin silver amalgam, Ti-core,

Ketac-Silver and G-C Miracle Mix). They concluded that all post/core samples with

Ti-Core composite and Tytin silver amalgam completed the test with no failures.

5


All post/ core samples with Ketac-Silver material failed before the 4,000,000 test

cycle configuration and all failures were core failures. All post/ core samples with G-

C Miracle Mix material failed in a similar manner. With this simulated fatigue test,

Ti-Core material and Tytin silver amalgam were superior to both G-C Miracle Mix

and Ketac-Silver materials.

The authors11 in 1997 conducted a study to evaluate the in-vitro performance

and the failure characteristics of the carbon fiber post and core system. This study

compared the composipost system (comprising a carbon fiber post, a composite core

material, and a low viscosity Bis-GMA bonding resin) against stainless steel post and

composite core, gold alloy post and gold alloy core combinations. They concluded

that the specimens restored with the Composipost system exhibited inferior strength

properties in comparison to the other post and core systems tested.

The authors12 in 1997 conducted a study to evaluate the root reinforcement

with a resin bonded preformed post. The result of the study showed that force needed

to fracture the roots in zinc phosphate cement group were lower than in the composite

cement group.

The authors13 in 1998 conducted a study to evaluate the retention of three

endodontic posts cemented with five dental cements. This study compared the

retentive values of three posts (Flexi-post, AccessPost, and ParaPost) cemented with

five cements; Flexi-flow cement (Composite resin cement), Zinc phosphate, Advance

6


cement (Glass ionomer cement), Duet cement (Glass ionomer hybrid cement) and

Ketac-cem (Glass ionomer cement). They concluded that Flexi-post dowel with Flexi-

flow cement obtained the highest retentive value. Parapost dowel with Duet cement

exhibited the lowest retention value. The Flexi-post dowel demonstrated higher mean

retention than Access post or Para post dowels; Access post dowel was higher than

Para post dowel. Flexi-flow cement had the highest overall mean retention followed

by, Zinc phosphate, Advance, Ketac-cem, and Duet cements.

The authors14 in 1998 conducted a study to evaluate the retention of parallel-

sided titanium posts cemented with six luting agents. Two resin-ionomer hybrid

cements and 2 resin cements were tested with corresponding dentin bonding agents. A

Glass ionomer cement was also tested, and Zinc-phosphate cement served as the

control. Samples were tested in an Instron universal testing machine to catastrophic

tensile failure. They concluded that Advance cement (resin ionomer cement) with

Prime and Bond systems was found to be statistically more retentive than all other

groups tested. Cement It (resin cement) with Bond It (dentin bonding agent) and

Permalute (resin cement) with Permalute Primers A and B systems (dentin bonding

agents) demonstrated significantly greater retention than the other cements. There was

no statistically significant difference among Ketac Cem cement, Resinomer, and

zinc-phosphate cement.

The authors15 in 1998 conducted a study to evaluate the retention of post

with Resin cement, Glass ionomer cement and Hybrid cement and they

7


concluded that retention of posts was better with resin and glass ionomer cements

than with resin modified glass ionomer cement. The relative low retention of hybrid

cements was attributed to inconsistent powder to liquid ratio and presence of air voids

in the post space.

The authors16 in 1998 conducted a study to evaluate the affect of cement

thickness on retention of endodontic posts with a composite resin luting cement and it

was concluded that changes in composite resin luting agent thickness of upto 500 μm

do not decrease the retention of endodontic post.

The authors17 in 2000 conducted a study to compare the tensile bond strength

of adhesive resin cement to different post materials. They concluded that Panavia 21

produced consistently higher bond strength to all types of post material due to the

presence of adhesive monomer MDP (10-Methacryloxydecyl dihydrogen phosphate).

C&B metabond had consistently high bond strength to metal alloys but lower bond

strength with the Zirconium groups.

The authors18 in 2001 conducted a study to evaluate the use of reinforced

composite resin cement as compensation for reduced post length. The retention values

of stainless steel posts (parallel-sided ParaPost and tapered Dentatus) luted with

Flexi-Flow titanium-reinforced composite resin and zinc phosphate cements were

evaluated. They concluded that Flexi-Flow reinforced composite resin cement

compensated for the reduced length of shorter parallel-sided ParaPost and tapered

8


Dentatus dowels.

The authors19 in 2001 conducted a study to evaluate the in-vitro fatigue

resistance of Glass ionomer cements used in post-and-core applications. This study

evaluated the fatigue resistance of 2 new Glass ionomer cements, Shoufu Hi-Dense

and Fuji IX GP, and compared their mechanical behavior as a core material under

masticatory load with a silver-reinforced glass ionomer (ESPE Ketac-Silver) and a

silver amalgam (Cavex Avaloy LC). They concluded that silver amalgam was

significantly superior to all glass ionomer cements tested. The silver-reinforced glass

ionomer showed the highest rate of defect formation. Shofu Hi-Dense and Fuji IX GP

showed significantly fewer defects than Ketac-Silver.

The authors20 in 2004 conducted a study to evaluate the diametral tensile

strength of a resin composite core with nonmetallic prefabricated posts. The aim of

this study was to determine the influence of different types of posts on the fracture

resistance of resin composite core material using the diametral tensile strength test.

They concluded that when used with the composite core material, Light-Post,

Dentorama post, and FiberKor resulted in the highest diametral tensile strength

values, whereas ParaPost resulted in the lowest values.

The authors21 in 2006 conducted a study to evaluate the effect of silane on the

bond strengths of fiber posts. Fifty-four extracted human maxillary central incisors

and canines were endodontically treated. D.T. Light Post (DT, Bisco), FRC Postec

(FR, Ivoclar Vivadent), and ParaPost Fiber White (PP, Colt`ene/Whaledent) were

9


inserted using the resin adhesive system provided by the respective manufacturer. For

half of the specimens in each group, the fiber posts were treated with a silane solution

(Monobond S, Ivoclar Vivadent). A push-out test was performed on three different

sections of each root to measure bond strengths. They concluded that the use of a

silane coupling agent did not increase the push-out bond strengths of the three fiber

posts used in this study. All posts bonded to root dentin at the same magnitude.

Bonding is more predictable at the most coronal level of the root.

The authors5 in 2006 conducted a study to evaluate the effect of different

surface treatments on retention of glass-fiber endodontic posts. The tapered post

received 1 of 4 surface treatments: cleaning with alcohol, cleaning with alcohol and

conditioning with ED-Primer, airborne-alumina particle abrasion, or air-borne

alumina particle abrasion and conditioning with ED-Primer. They concluded that the

air-borne alumina particle abraded posts had significantly higher retention compared

with the non-abraded posts. Treating the post surface with ED-Primer material prior

to cementation had no significant effect on retention.

The authors2 in 2006 conducted a study to evaluate the resistance of three new

esthetic post-and-core systems to compressive loading. Three experimental

groups consisted of a stainless steel post with composite-resin core group, zirconium

dioxide post with composite-resin core group, and zirconium dioxide post with

ceramic core group. The cast metal post and core group served as the control. They

concluded that the cast metal post with metal core and zirconia post with ceramic core

10


foundations were found to be more fracture resistant than the other post and core

groups. Aside from it’s desirable esthetic properties, the zirconia post with ceramic

core combination demonstrated high resistance to fracture.

The authors22 in 2007 conducted a study to evaluate the flexural modulus and

flexural strength of different types of endodontic post in comparison with human root

dentin. Fiber-reinforced composite (FRC) posts have an elastic modulus that more

closely approaches that of dentin while that for metal posts was much higher. The

flexural strength of fiber post and metal posts was respectively four and seven times

higher than root dentin.

The authors23 in 2007 conducted a study to evaluate flexural strength of

different fiber reinforced post systems. Eight types of fiber post were selected for this

study. Fiber Kor (Jeneric-Pentron), Para Post Fiber White (Coltene), Luscent Anchor

(Dentatus), Twin-Luscent Anchor (Dentatus), Style Post (Metalor), DT White-Post

(VDW), DT Light-Post (VDW) and ER Dentin Post (Brasseler) A universal testing

machine loading at an angle of 90◦ was employed for the three-point bending test.

The test was carried out until fracturing of the post. They concluded that the flexural

strength of the fiber reinforced systems ranged from 565 to 898MPa. DT White-Post

and DT Light-Post (898 and 842MPa, respectively) had significantly higher flexural

strengths than the other posts. Style Post (565MPa) showed a significantly lower

flexural strength than all other posts.

The authors24 in 2007 conducted a study to evaluate .the rotational fatigue-

11


resistance of seven post types anchored on natural teeth. They concluded that in

increasing order of magnitude, the resistances to fatigue loading were as follows:

Biopost (Zirconium oxides Y-TZP), Unimetric-T (Titanium), Unimetric-SS (Stainless

steel), Composipost (Carbon fibers), Easypost (Si–Zr fibers), Everstickpost (E-glass

fibers), DT Lightpost (Quartz fibers).

The authors25 in 2007 conducted a study to evaluate the effect of sandblasting

on adhesion of a dual-cured resin composite to methacrylic fiber posts. They

concluded that sandblasting increases the microtensile strength to methacrylate-

based glass fiber posts, thus eliminating the need for additional ‘‘chair-side’’

treatments like Silane application (Monobond S, Ivoclar Vivadent) or Adhesive

application (Unifil Core self-etching bond).

The authors26 in 2007 conducted a study to evaluate the fracture resistance of

anterior endodontically treated teeth prepared with a 2-mm ferrule, restored

with glass fiber and zircon posts and composite resin cores or cast posts and cores.

They concluded that the teeth restored with glass fiber and zircon posts

demonstrated significantly lower failure loads than those with cast NiCr post and

cores. All specimens failed via root fractures.

The authors27 in 2008 conducted a study to evaluate the effect of two fiber

post types and two luting cement systems on regional post retention using the push-

out test. The crowns of 24 recently extracted sound maxillary central incisors were

sectioned transversely 2mm coronal to the labial cemento-enamel junction, and the

12


roots were treated endodontically. Following standardized post space preparations,

fiber-reinforced posts (C-POST; AESTHETI-PLUS) were placed using two adhesive

systems (acid-etch one-step plus/C&B cement; self-adhesive RelyX Unicem), in four

equal groups. Push-out bond strength tests were performed at four sites in each root.

They concluded that AESTHETI-PLUS (quartz fiber-reinforced posts) showed

significantly higher push-out strengths than C-POST (carbon fiber-reinforced posts).

The authors28 in 2008 conducted a study to compare the tensile strength of

commercially pure titanium and type III cast gold-alloy posts and cores cemented

with zinc phosphate or resin cement. Forty-two extracted human canines were

endodontically treated. The root preparations were accomplished using Largo reamers

(10 mm in depth and 1.7 mm in diameter). Acrylic resin patterns for the posts and

cores were made, and specimens were casted in commercially pure titanium and in

type III gold alloy. Fourteen titanium cast posts and cores were submitted to surface

treatment with Kroll acid solution and to scanning electron microscopy (SEM), before

and after acid etching. The groups were cemented with zinc phosphate cement or

resin cement (Panavia F). Tensile strengths were measured in a universal testing

machine at a crosshead speed of 0.5 mm/min. They concluded that there were no

significant differences among the groups tested. Retentive means for zinc phosphate

and Panavia F cements were statistically similar. The bond strength was not

influenced by the alloy, the luting material, or the etching treatment. SEM analysis

indicated that the etched surfaces were smoother than those that did not receive

surface treatment, but this fact did not influence the results.

13


The authors29 in 2008 conducted a study to evaluate the static and fatigue

fracture resistances of pulpless teeth restored with post–cores. Extracted human

premolars were restored with a combination of either a fiber post or metallic post and

a composite resin core. Teeth with full crown preparations without post–core

restorations served as a control. A 90◦ vertical or 45◦ oblique static compressive load

was applied to restored teeth, and fracture loads and modes of fracture were recorded.

Fatigue fracture tests were conducted by applying sinusoidal cyclic loads to restored

teeth from vertical or oblique directions. They concluded that in both static and

fatigue fracture testing under vertical or oblique loadings, the fracture loads of teeth

restored with fiber posts were significantly greater than those of teeth restored with

metallic posts. The fatigue limits of teeth restored with fiber and metallic posts were

112 kilogram force (kgf) and 82 kgf respectively under vertical loadings and 26 kgf

and 20 kgf under oblique loading.

14

Methodology

The present in-vitro study was carried out to evaluate the effect of different

surface treatments on the retentive strength of glass fiber posts, carbon fiber posts and

cast metal posts.

Materials and Armamentarium used (figure 1).

A. Materials used for specimen preparation 1. Custom made device of stainless steel- Hollow cubical mold without roof

of the following dimensions-

Length-40 millimeter (mm), Width-40mm, Height-25mm with uniform wall

thickness of 6mm. For easy holding of cubical mold during testing a 2mm

thick stainless steel plate was welded below it (figure-2 and 3).

2. Auto-polymerizing poly-methyl methacrylate resin (DPI-RR Cold cure,

DPI, Mumbai, India)

3. Extracted human teeth with single root canal.

4. Elastomeric impression material: Addition polyvinylsiloxane (Aquasil, Soft

Putty/regular set, Dentsply, Germany) 5. Petroleum Jelly (Nice chemicals Pvt. Ltd, Cochin)

B. Materials and armamentarium used for sectioning the teeth and

preparation of post spaces

1. Diamond burs (Preparation set, Shofu Inc, Kyoto, Japan) 2. Air-rotor hand piece (Pana-Air, NSK Nakanishi Inc, Tochigi-ken, Japan)

3. Endo-files (K-file, Dentsply DeTrey GmbH, Constance, Germany).

15

Methodology

4. Sodium Hypochlorite- 3% solution (Vensons India, Bangalore, India)

5. Drill Bit for preparation of post spaces – Size 2 (R.T.D, France)

C. Materials and Armamentarium used for post and cementation of posts

1. Glass Fiber Posts with diameter of 1 mm at apex –size 2 (D.T. Light post,

R.T.D, France)

2. Carbon Fiber posts with diameter of 1 mm at apex –size 2 (D.T. Carbon

post, R.T.D, France)

3. Ni-Cr alloy ( Wiron, Bego, Bremen, Germany )

4. Aluminium oxide blasting material-50µm (Korox 50, Bego, Bremen,

Germany)

5. Ethyl Alcohol 57.1% (Surgical Spirit, Reliance Pharmaceutical

Laborateries, Hyderabad, India)

6. Primer (Rely a Bond, Reliance products, U.S.A.)

7. Dual cure resin cement (Rely x ARC, 3M ESPE, U.S.A)

8. Phosphate bonded investment material (Bellasun, Bego, Bremen, Germany)

9. Silli Rings ( Ringless casting rings, Vijai Dental Products, Chennai, India )

10. Vaccum Mixing Machine (Wehmer, U.S.A.)

11. Burn-out Furnace (Sidesco, Bangalore)

12. Induction Casting Machine (Degutron, Degussa AG, Germany) (figure 6).

D. Instrument used for measurement of retentive strength

1. Universal Testing Machine with a cross head speed of 2mm/min. (Instron

33R 4467, Instron limited, Buckinghamshire, England) (figure 7).

16

Methodology

Method

1. Ninety extracted caries-free and visually assessed fracture free, human

maxillary anterior teeth and mandibular premolar teeth were selected. The selected

teeth were cleaned of both calculus deposits and soft tissue, and stored in distilled

water.

2. A thin layer of petroleum jelly was applied to the inner walls of hollow

cubical mold. Thereafter, the mold was filled with a mix of auto-polymerizing acrylic

resin. After polymerization, the poly-methyl methacrylate block (PMMA) was

removed from the cubical mold. The PMMA block was subsequently duplicated using

elastomeric impression material. All the PMMA blocks were tested for the fit in the

cubical mold. If there was any interference, it was removed by trimming. After the fit

of the PMMA blocks was checked, a hole was made in the center of these blocks.

Total ninety PMMA blocks were prepared for mounting the teeth. Notches were

prepared in root of the teeth to prevent dislodgement during testing and subsequently

each tooth was mounted in the hole made in the PMMA block till cemento-enamel

junction with a fresh mix of auto-polymerizing acrylic resin.

3. Each tooth was sectioned with a diamond rotatory cutting instrument under water spray, 1 mm coronal to the cemento-enamel junction. Roots with distinctly

oval canal and diameter of more than 2mm were excluded from the study. The pulpal

tissue was removed and canal was enlarged with Endo files up to size 40. 3% Sodium

hypochlorite solution was used to irrigate the canal throughout instrumentation.

17

Methodology

. 4. Specific drill bit of size 2 supplied for the prefabricated fiber post size 2 was

marked at 9mm length from the tip using permanent marker and post spaces of 9mm

in length were prepared(figure 4). New instrument was used for every 8 specimens.

Throughout the preparation, the post spaces were irrigated with 3% Sodium

hypochlorite solution. The prepared post spaces were dried.

5. Acrylic patterns of the post spaces of thirty specimens were made for cast

metal posts and were numbered. Subsequently they were invested and casted with Ni-

Cr alloy using an Induction Casting Machine.

6. All the specimens were divided into 9 groups. Each group contained 10

specimens.

GROUP 1- Carbon fiber posts cleaned with 57.1% ethyl alcohol for three minutes.

GROUP 2- Carbon fiber posts conditioned with resin primer for 60 seconds.

GROUP 3- Carbon fiber posts air abraded with 50µm alumina particles for 5 seconds

from a distance of 30mm.

GROUP 4- Glass fiber posts cleaned with 57.1% ethyl alcohol for three minutes.

GROUP 5- Glass fiber posts conditioned with resin primer for 60 seconds.

GROUP 6- Glass fiber posts air abraded with 50µm alumina particles for 5 seconds


GROUP 7- Cast metal posts cleaned with 57.1% ethyl alcohol for three minutes.

GROUP 8- Cast metal posts conditioned with resin primer for 60 seconds.

18

Methodology

GROUP 9- Cast metal posts air abraded with 50µm alumina particles for 5 seconds


7. All the surface treated posts were marked at 9 mm (millimeter) from the

apex using permanent marker and subsequently luted with Dual cure resin cement

(figure 5a,b,c). Cement was not light cured to standardize the study, as carbon fiber

post and cast metal posts were also used.

8. For the Retentive force test, a screw driven universal testing machine was

used to apply tensile load to the post at a cross head speed of 2mm/min (figure 8a,b).

The force required to dislodge each post from prepared post space was recorded. The

data was subjected to statistical analysis.

19

Methodology

Figure 1: Armamentarium used for the study

Figure 2: Custom made device (lateral view)

20

Methodology

Figure 3: Custom made device (superior view)

Figure 4: PMMA Blocks with sectioned teeth and prepared post spaces

21

Methodology

Figure 5a: Carbon fiber posts luted with dual cure resin cement

Figure 5b: Glass fiber posts luted with dual cure resin cement

22

Methodology

Figure 5c: Cast metal posts luted with dual cure resin cement

Figure 6: Induction Casting Machine

23

Methodology

Figure 7: Universal Testing Machine

Figure 8a: Universal Testing Machine with the custom made device

24

Methodology

Figure 8b: Universal Testing Machine and the dislodged post

25

Results

Retentive strength of Glass fiber posts, Carbon fiber posts and Cast metal

posts surface treated with ethyl alcohol, resin primer and airborne alumina particle

abrasion were compared. Retentive strength of Group 1 to 9 is listed in Table I to XI

respectively. Means and standard deviations of each group are listed in Table X.

Comparison of the mean retentive strength using two-way Analysis of Variance

(ANOVA) is listed in Table XI. From the two way ANOVA test we observe that

type of post is a significant factor influencing retentive strength and there is a

significant difference between the different posts (P<0.001). We also notice that

“Surface Treatment” is a significant factor influencing retentive strength and there is a

significant difference between the different surface treatments (P<0.001). Also, the

interaction effect of post and surface treatment is significant (P<0.001). In order to

find out among which of the posts there exist a significant difference, we carry out

post-hoc (multiple comparisons) test using Bonferroni method (Table XII)

From the multiple comparisons table we notice that there is a significant

difference in retentive strength between Carbon fiber posts and Cast metal posts

(P<0.001). We also notice a significant difference between Glass fiber posts and Cast

metal posts (P<0.001). There is no significant difference in retentive strength between

Carbon fiber posts and Glass fiber posts (P>0.05). Similarly, post-hoc (multiple

comparisons) test using Bonferroni method was carried out to find out among which

of the treatments there exist a significant difference (Table XIII).

We observe in Table XIII that there is a significant difference in the retentive

26

Results

strength between air borne alumina particle abrasion and ethyl alcohol treated posts

(P<0.001). We also notice a significant difference in the retentive strength between air

borne alumina particle abrasion and resin primer treated posts (P<0.001). There was

no significant difference between ethyl alcohol and resin primer treated posts

(P>0.05).

Retentive strength of each group is showed in the bar diagram in Graph-I.

From the Graph II we notice that type of post is the most important factor

influencing retentive strength followed by treatment. Among the different posts, cast

metal posts yields a higher retentive strength followed by carbon fiber posts and glass

fiber posts and this difference is found to be statistically significant (P<0.001).

Among the different surface treatments, abrasion yields a higher retentive strength

followed by ethyl alcohol and resin primer and this difference is found to be

statistically significant (P<0.001).

From the Graph III we notice that cast metal posts yields a higher retentive

strength compared to carbon fiber posts and glass fiber posts in all the three

treatments. Glass fiber yields the least retentive strength in all the three treatments.

27

Results

Table I (Group-1)

Sl No. Name of the specimen Maximum load (kgf)

1. Carbon fiber post treated with ethyl alcohol 4.662










Table II (Group 2)


1. Carbon fiber post treated with resin primer 6.007


28

Results









Table III (Group 3)


1. Carbon fiber post air abraded with alumina 13.648









29

Results


Table IV (Group 4)


1. Glass fiber post treated with ethyl alcohol 4.369










Table V (Group 5)


1. Glass fiber post treated with resin primer 6.295


30

Results









Table VI (Group 6)


1. Glass fiber post air abraded with alumina 10.071








31

Results



Table VII (Group 7)


1. Cast metal post treated with ethyl alcohol 14.009










Table VIII (Group 8)


1. Cast metal post treated with resin primer 16.373


32

Results









Table IX (Group 9)


1. Cast metal post air abraded with alumina 20.096









33

Results


Table X

Post Treatment Mean Std Dev

Abrasion 13.07 2.46

Alcohol 6.79 2.10 Carbon Fiber

Primer 6.25 1.71

Abrasion 28.97 7.00

Alcohol 14.32 4.28 Cast Metal

Primer 13.46 4.54

Abrasion 11.90 1.62

Alcohol 4.93 1.24 Glass Fiber

Primer 5.78 2.18

Table XI

Source DF Sum of Squares (SS) Mean SS F P-Value

Post 2 2234.19 1184.63 98.59 <0.001

Treatment 2 1830.86 957.90 79.72 <0.001

Post Treatment 4 349.32 87.33 7.27 <0.001

34

Results

Error 85 1021.32 12.02 --- ---

Total 93 5435.70 --- --- ---

Table XII

Multiple Comparisons

Dependent Variable: Tensile StrengthBonferroni

-9.59529* .874428 .000 -11.73089 -7.459691.58693 .867009 .212 -.53055 3.704419.59529* .874428 .000 7.45969 11.73089

11.18222* .887759 .000 9.01406 13.35038-1.58693 .867009 .212 -3.70441 .53055

-11.18222* .887759 .000 -13.35038 -9.01406

(J) PostCast MetalGlass FiberCarbon FiberGlass FiberCarbon FiberCast Metal

(I) PostCarbon Fiber

Cast Metal

Glass Fiber

MeanDifference

(I-J) Std. Error Sig. Lower Bound Upper Bound95% Confidence Interval

Based on observed means.The mean difference is significant at the .05 level.*.

35

Results

Table XIII

Multiple Comparisons Dependent Variable: Tensile Strength Bonferroni

95% Confidence Interval

(I)Treatment

Mean Difference (I-J)

Std. Error

Sig. Lower Bound Upper Bound

Abrasion Alcohol Primer

8.56414* 8.67751*

.887874 .847813

.000 .000

6.60692

10.73258 10.74811

Alcohol Abrasion Primer

-8.56414* .11337

.887874 .905818

.000 1.000

-10.73258 -2.09889

-6.39570 2.32563

Primer Abrasion Alcohol

-8.67751* -.11337

.847813 .905818

.000 1.000

-10.74811 -2.32563

-6.60692 2.09889

Based on observed means. * The mean difference is significant at the .05 level.

. Graph I

Mean Tensile Strength recorded in different posts and treatments

13.07

28.97

11.90

6.79

14.32

4.936.25

13.46

5.78

0

5

10

15

20

25

30

35

Carbon Fiber Cast Metal Glass Fiber

Post

Tens

ile S

treng

th

Abrasion

Alcohol

Primer

36

Results

Graph II M

ean

of T

ensi

le S

tren

gth

Glass FiberCast MetalCarbon Fiber

20

18

16

14

12

10

8

6PrimerAlcoholAbrasion

Post Treatment

Main Effects Plot (fitted means) for Tensile Strength

Graph III

Tr e a t me n t

Mea

n

P r im e rA lcoho lA b ra s ion

30

25

20

15

10

5

P o st

G lass F ib er

C ar b o n F ib erC ast M eta l

Inte r a c tio n P lo t ( f i tte d m e a ns ) fo r T e ns i le S tr e ngth

37

Discussion

Restorative methods for pulpless teeth with post–core systems have been

widely investigated with the aim of achieving long term promising prognosis. Use of

post is still regarded as the accepted method of core retention for restoration of

pulpless teeth which have suffered significant loss of the coronal structure.29

Extensive research has been carried out on the materials to be used to fabricate

the post and core. Cast metal posts and core foundations have a long history of

successful use due to their superior physical properties.2 However, their high elastic

modulus, corrosion and esthetic problems have led to development of other types of

post systems.

For fifteen years endodontic posts made of fiber reinforced composites (FRC)

have been described in the literature. Glass, silica and carbon fiber reinforced

materials especially, have been marketed and provided the dental profession with the

first true alternative to cast or pre-fabricated metal posts. 23

Certain properties, such as biocompatibility and corrosion resistance makes

the carbon fiber post a potential replacement for cast metal posts in many clinical

situations. Also, as with cast posts, the use of carbon posts has generally limited

esthetic expectations. Their dark underlying color can adversely influence the shade

of overlying gingival tissues and prosthetic restorations.1

Tooth colored posts such as glass fiber posts or zirconia posts are believed

to result in improved esthetics when used for anterior teeth to be restored with all-

38

Discussion

ceramic crowns. Glass-fiber posts are composed of glass fibers, inorganic filler, and a

resin matrix. They are usually luted with a resin cement to increase their retention and

improve the mechanical performance of the restored teeth.5 These posts have modulus

of elasticity values that approximate that of dentin and are believed to help prevent

root fracture.20 Another advantage is in endodontic retreatment, as most fiber posts

can be removed from a root canal with ease and predictability, when necessary.

Many in-vitro studies have investigated various factors that affect retention of

the post. These factors include length, design, diameter and the surface treatment of

the post. A study done by Ibrahim Nergis, Dr Med Dent and Peter Schamage5showed

that roughening the prepared dentinal surface also increased the retention of posts or

artificial crowns by increasing the surface area and enhancing the mechanical

interlocking between the dentin surface and the cement. Material used in fabrication

of the post can also influence the retentive strength of posts. John R. Gallo and Troy

Miller[4] in their study have reported that fiber-reinforced resin posts provided lower

retention when compared with metal posts.

In the present study single rooted teeth with a single root canal were

employed. Posts employed were of same length, diameter and taper. Post spaces were

prepared to 9mm in length for all the posts with the specific drill bit provided by the

manufacturer for the specific size of post. This was done to standardize the length and

diameter of posts. Posts were marked at 9mm length from apex with a permanent

marker to check whether the posts have seated properly or not. Posts were luted with

dual cure resin cement. However, dual cured cement was not light cured as the cast-

39

Discussion metal posts and carbon fiber posts were also employed in the study through which

light is not transmitted.

For the Retentive force test, a screw driven universal testing machine was

employed to apply tensile load to the post at a cross head speed of 2mm/min. The

force required to dislodge each post from prepared post space was recorded in

kilogram force (kgf). Then the readings were analysed using two-way ANOVA.

The results obtained in this study indicates that the air-borne alumina particle

abraded cast-metal posts had the highest retentive strength compared to all other

surface treated or untreated posts employed in the study. Resin primer treated and

ethyl alcohol treated cast metal posts had the next highest retentive strength. It was

followed by airborne alumina particle abraded glass fiber posts and carbon fiber posts.

Airborne alumina particle abrasion increased the retentive strength of all the

posts used in this study. Treating the surface of the posts with resin-primer and ethyl

alcohol produced no statistically significant difference in the retentive strength of all

the type of posts used in the study. Further, there was no significant difference in the

retentive strength observed between glass fiber posts and carbon fiber posts.

The above findings indicate that air borne alumina particle abrasion of the

surface increased the retention of all the posts. However, resin primer treatment of

the posts does not significantly affect the retentive strength. These findings are similar

to the findings of Ali Balbosh and Matthias Kern.5 The findings observed may be

40

Discussion

because the non-abraded posts had a relatively smooth surface area, which limited

mechanical interlocking between the post’s surface and the resin cement. A careful

visual observation with a magnifying lens of the dislodged posts revealed purely

adhesive failure mode at the resin cement/ post interface for all non-abraded posts.

The airborne alumina particle abraded posts were rougher and appeared to provide an

increased surface area which improved mechanical interlocking for the resin. Among

all the specimens tested, two teeth which were cemented with air borne-alumina

particle abraded cast metal posts, fractured during testing at 45 kgf and 46 kgf

respectively. However, none of the teeth of the test specimens cemented with glass

fiber posts and carbon fiber posts fractured during testing. The above finding also

supports that air borne alumina particle abrasion of the posts increases the retentive

strength.

The test for retention of different surface treated posts in this study was carried

out shortly after cementation. However, clinically the dislodgement of post-retained

restorations commonly occurs after several years of function. Long-term retention

may be influenced by various factors such as temperature changes and dynamic

mechanical loading. In this study artificial aging, which simulates to oral

conditions was not carried out. Further, other post systems like, threaded posts,

serrated posts, parallel posts and zirconia posts were not considered in the study. All

the posts used in this study were smooth, tapered and of same size. All the posts were

cemented with dual cured resin cement, which was not light cured. If dual cured

cement used in the study was light cured, then the glass fiber posts would have

probably given different retentive values during testing as light can transmit through

41

Discussion

it. Further, the surface details of the dislodged posts were also not analysed under

scanning electron microscope (SEM). Visualization under SEM can provide better

insight for the findings observed in the study.

42

Conclusion

The present study was done to evaluate the effect of surface treatment with ethyl

alcohol, resin primer and air-borne alumina particle abrasion on the retention of glass

fiber posts, carbon fiber posts and cast metal posts. The retentive strengths were

obtained using screw driven universal testing machine. The readings were subjected

to statistical analysis. The results indicate that

• Air-borne alumina particle abraded cast-metal posts had the highest retentive

strength compared to all other surface treated or untreated posts used in the

study followed by primer treated cast metal posts and ethyl alcohol treated

cast metal posts.

• Airborne alumina particle abraded glass fiber posts and carbon fiber posts had

the next highest retentive strengths.

• Airborne alumina particle abrasion increased the retentive strength of all the

type of posts used in this study.

• Treating the surface of the posts with resin-primer and ethyl alcohol produced

no statistically significant difference in the retentive strength of all the type of

posts used in the study.

• There was no significant difference in the retentive strength obtained between

Glass fiber posts and carbon fiber posts.

43

Summary

The retentive strength of the post depends on several factors like length,

design, diameter and the surface treatment of the post. Hence, all the factors must be

thoroughly understood in order to know their effect on the retentive strength of the

posts.

Type of surface treatment is one of the important factors influencing the

retentive strength of posts. The present in-vitro study was conducted to compare

effect of surface treatment with ethyl alcohol, resin primer and air-borne alumina

particle abrasion on retention of glass fiber post, carbon fiber post and cast metal

posts.

Ninety test specimens were made. Test specimens were divided into 9 groups,

each containing 10 specimens. Canals of all the test specimens were prepared with a

specific drill bit till a standard length. The surface treated posts subsequently were

luted with dual cure resin cement. For the Retentive force test, a screw driven

universal testing machine was used to apply tensile load to the post. The force

required to dislodge each post from prepared post space was recorded. The data was

analysed using two-way ANOVA test.

The results obtained in this study showed that air-borne alumina particle

abrasion increased the retentive strength of all the type of posts used in this study.

Treating the surface of the posts with resin-primer and ethyl alcohol produced no

statistically significant difference in the retentive strength.

44

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