A COMPARATIVE ANALYSIS OF THE EFFECT ON GINGIVAL ...

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A COMPARATIVE ANALYSIS OF THE EFFECT ON GINGIVAL

DISPLACEMENT BY THREE DIFFERENT GINGIVAL

RETRACTION SYSTEMS – IN VIVO STUDY

Submitted by

Dr. NAHAD ABDUL NASER.O

Dissertation submitted to the

Rajiv Gandhi University of Health Sciences, Karnataka, Bengaluru,

In partial fulfillment of the requirements for the degree of

MASTER OF DENTAL SURGERY

IN

PROSTHODONTICS INCLUDING CROWN AND BRIDGE

Under the guidance of

DR. OMPRAKASH .Y.V, M.D.S

PROFESSOR AND HEAD

PROSTHODONTICS INCLUDING CROWN AND BRIDGE

FAROOQIA DENTAL COLLEGE AND HOSPITAL

Mysuru-570021, Karnataka, India

2015-2018

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ACKNOWLEDGEMENT

First and foremost, I would like to thank the Almighty God for the inspiration

and strength which help me to finish this study. It gives me an immense pleasure and

gratitude to acknowledge the enthusiastic participation of the people, without whom

this endeavor of mine would have been unattainable.

My most sincere and deepest thanks to my guide Dr. OMPRAKASH .Y. V,

Professor and Head, Department of Prosthodontics including Crown and Bridge,

Farooqia Dental College and Hospital, Mysuru , for his constant, selfless guidance,

helpful suggestion and advice. This work would never have possible without his

motivation & reinforcement. I am grateful to former head of the department Dr.

HARASWARUPA GURKAR., Professor, Department of Prosthodontics including

Crown and Bridge, giving me support, indefatigable efforts, guidance, invaluable

suggestions and encouragement.

I extend my heartfelt thanks to Dr. JAGADEESH M. S, Reader, who paved

the path towards perfection in completing this study, who provided me priceless

guidance and support during the entire course of study. I am thankful to

Dr. ABHILASH., Dr. MUTHURAJ H. L., Readers, for their valuable guidance and

constant encouragement. I am thankful to Dr. NEHA NANAL, Senior Lecturer, for

guiding me during the entire process of this study. Her kind guidance and

knowledge on the subject has helped me organize and complete this study for. I

also thank Dr. ZAHARA BATHOOL, Lecturer for giving me support and

guidance whenever I have needed.

Their valuable guidance, persistent efforts and continuous inspiration has

helped me in achieving this goal. Their innovative ideas, strict discipline and tireless

support have made this study achievable. I am forever indebted to them for everything

that they have taught me.

I sincerely thank Dr. B G YOGESH, Principal, Farooqia Dental College &

Hospital, Mysuru, for his kind help and cooperation during my post graduate studies

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Special thanks to my seniors, Dr. ISHANI NINGTHOUJAM Dr.

MADHAVI DWIVEDI, and junior post graduates, Dr.SHAREEQ MOHAMMED,

Dr. TEJASWINI M.S., Dr. DEEPIKA for their continued interest and immense

support during compilation of the study.

I also would like to thank my parents ABDUL NASER and LAILA

ABDUL NASER and my wife DR. MANOLY SHABNAM, for being there with

me when I needed the most.

My family, in-law family and all my near & dear friends, who have stood by

me in every walk of life and this acknowledgement is not complete without their

mention, as my Post Graduate curriculum would not have been possible without their

support.

I would also acknowledge staff, colleagues in other specialty, and the non

teaching staff of the Department of prosthodontics including crown and bridge, for

their help in completing this study.

The full list of those assisted in my thesis would fill many pages. My apologies

go with my thanks to those I have omitted.

Dr. NAHAD ABDUL NASER

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LIST OF ABBREVIATIONS USED

C Center

D Distal

HSD Highly significant difference

Mm Millimeter

M Mesially

p- Value Probability value

SD Standard Deviation

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LIST OF TABLES

Table

No. Title Page No.

1 Values obtained by Vernier Caliper (Cord) 32

2 Values obtained by Vernier Caliper (Expasyl) 33

3 Values obtained by Vernier Caliper (Merocel strip) 34

4 Descriptive Statistics; Mesially on Facial side 35

5 Descriptive Statistics; Middle on Facial side 35

6 Descriptive Statistics; Distal on facial side 35

7 Descriptive Statistics; Mesial on palatal side 36

8 Descriptive Statistics; Middle on palatal side 36

9 Descriptive Statistics; Distal on palatal side 36

10 Mean Retraction on each Material 36

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LIST OF FIGURES

Fig No. Title Page No.

1 Mouth Mirror, William’s Periodontal Probe, Tweezers, Cord

Packer (Hu-Friedy, Usa), Scissors- Straight and Angled,

Digital Vernier Caliper, Surgical Gloves, Mouth Mask,

Cotton Rolls, Cheek Retractor

56

2 Conventional Retraction Cord (Ultrapak, Ultradent, USA) 56

3 Expasyl Retraction Paste and Dispensing Gun 57

4 Merocel Retraction Strip 57

5 Tooth Preperation 57

6 Placing Cord Using Cord Packer 57

7 Conventional Retraction Cord Placed 58

8 Expasyl Placed 58

9 Merocel Retraction Strip Placed 58

10 Measurements Taken Using Digital Vernier Caliper 58

11 Cementation of Final Prosthesis 58

LIST OF GRAPHS

Graph No. Title Page No.

1 Showing Maximum Gingival Displacement by Retraction

Cord Followed by Expasylcord and Merocel Strip

Respectively.

37

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ABSTRACT

Objective: This comparative study aim to determine the amount of gingival retraction

produced by retraction cord, Expasyl and Merocel strip. And to compare the amount

of retraction produced by cord, Expasyl and Merocel strip

Methodology: The study was done using three groups, the same patients served for

all the groups. In one group (Group A) the retraction was done using the retraction

cord (Ultrapak, Ultradent, USA) at the time of tooth preperation and after a two week

time interval patient recalled for metal trail and the Merocel (Mystic, Conn) was

tested in the other group (Group B) then again after two week time interval patient

recalled for cementation and expasyl was also tested. In (Group C).

For the clinical procedure, the tooth was prepared with a equi-gingival level without

retraction of the gingival sulcus. Clinical measurements were initially recorded

immediately before retraction on the buccal and palatal aspect at three points on each

side that coincided with the mesial line angle, distal line angle and at the deepest point

on the preparation to the crest of the free gingival margin. The measurement was

recorded linear from the prepared finish line to the free gingival margin using digital

vernier caliper.

A 2 mm thick Merocel retraction strip was inserted around the tooth using cord packer

(Hu-Friedy, USA) and the provisional crown inserted. The patient was asked to

maintain pressure on the artificial crown and concomitantly on the Merocel strip with

the use of a cotton roll. This position was sustained for 10 minutes. The Merocel

retraction strips tended to expand with absorption of selected oral fluids, exerting

pressure on surrounding tissues to provide gingival retraction. The materials in the

intracrevicular space were removed and the measurements repeated.

After two weeks at the time of metal trial the retraction was done using conventional

plain retraction cords, which were packed dry into the sulcus without any chemicals

using “000” cord first followed by “0” (double cord technique). The measurements

were recorded as before.

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After two weeks again at the time of cementation retraction is done using Expasyl and

measurement were recorded as before All the measurements were done by a single

operator.

Results:

Conventional retraction cord produced statistically significant amount of gingival

retraction. When compared with the displacement produced by Expasyl, the

displacement produced by conventional retraction cord is significantly more. When

compared with the displacement produced by Merocel retraction strip the

displacement produced by the Expasyl is significantly more.

Conclusion:

1. Conventional retraction cord produced statistically significant amount of

gingival retraction (p<0.001).

2. When compared with the displacement produced by Expasyl, the displacement

produced by conventional retraction cord is significantly more (p<0.001)

3. When compared with the displacement produced by Merocel retraction strip

the displacement produced by the Expasyl is significantly more (p<0.001)

4. All the three materials and methods of displacement have not grossly affected

the gingival health in 2 weeks follow-up.

Keywords: Retraction cord; Expasyl; Merocel Strip; Digital Vernier Caliper;

Abutments; Midbuccal region; finish line.

Introduction

Page 1

A COMPARATIVE ANALYSIS OF THE EFFECT ON GINGIVAL

DISPLACEMENT BY THREE DIFFERENT GINGIVAL

RETRACTION SYSTEMS – IN VIVO STUDY

INTRODUCTION

Gingival retraction is mandatory for adequate lateral displacement of gingiva, for

adequate flow of low viscosity impression materials into the sulcus and for accurate

capturing of prepared finish line and a portion of apical uncut tooth structure1. It helps

in obtaining the perfect die with accurate margins, which helps in margin placement

and contouring of the restoration. It helps in blending of the restoration with the

unprepared tooth surface. It also helps in placement and finishing of the margins on

the prepared tooth. During cementation it helps in easy removal of cement without

tissue damage. It helps the dentist in visually assessing the marginal fit and any caries

if present. To enhance access and to prevent damage to the soft tissue during tooth

preparation procedure, it may be desirable to carry out some degree of gingival

retraction prior to commencement of preparation2

Harmony between a restoration and the periodontium that surrounds the teeth is

crucial for the success of a restorative procedure. Key to achieving such a relationship

is an accurately made impression for indirect restorations or a properly placed direct

restoration into the prepared cavity. Displacement of the gingival tissues is essential

for obtaining accurate impressions for the fabrication of fixed restorations,

particularly when the finish line is at, or just within the gingival sulcus. This is also

true when dealing with the restoration of cervical lesions to their proximity to the

periodontal tissues. To obtain consistent predictable results, the dentist must alter the

armamentarium and techniques to meet specific demands.

Introduction

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The effective ideal gingival displacement should ensure the health of the epithelial

attachment. The technique used for this should be atraumatic to the periodontal

tissues. While recording impressions of subgingival crown margins or restoring

cervical lesions, the clinician must often displace the crown to record the finish line to

gain access to the prepared margins.

The methods used for displacing the gingiva include mechanical, chemo-mechanical,

and surgical3. The use of conventional retraction cords as a mechanical or chemo-

mechanical technique is well established in practice due to their relative predictability,

effectiveness, and safety compared with rotary gingival curettage and electro-surgery.

Recently, cordless technique such as expanding polymers and expanding gingival

displacement materials in the form of a paste have been introduced which are said to

save time and enhance patient comfort while being minimally invasive. Soft tissue

lasers are gaining popularity in its effectiveness and predictability as a retraction

method. Although crucial advances have been made in the hydrophilicity of

impression materials and in their ability to reproduce detail, making an impression is

still a concern, especially when preparation finish lines are located subgingivally4

However, the use of conventional retraction cord can be laborious, time-consuming,

can cause gingival bleeding, uncomfortable for patients in the absence of anesthesia,

and when inappropriately manipulated, can lead to direct injury and gingival

recession. The desirable qualities of a conventional retraction cord are that it is dark:

it is dark in colour, to maximize contrast with the tissues, tooth and cord; it acts as an

absorbent, to allow the uptake of the liquid medicaments; and they are available in

different diameters to accommodate varying morphologies of gingival sulcus. Various

haemostatic agents with varying degrees of safety and effectiveness are available such

Introduction

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as aluminum potassium sulphate (Alum), aluminum chloride, epinephrine, zinc

chloride, ferric sulphate and sympathomimetic amines. In this study we are using

without haemostatic agent.

Cordless techniques have been introduced with several claimed advantages, such as

time-savings and enhanced patient comfort while being minimally invasive5. Expasyl

gingival retraction paste is an effective and tissue friendly product designed as an

alternative to retraction cord placement for hemostasis. The product is user friendly

for crown and bridge impressions, fillings, veneers or many other application in which

there is a need to maintain a dry field6. Expasyl was introduced by Satelac Pierre

Rolland. It has a specially formulated consistency which exerts moderated calculated

pressure on gingiva. It has both mechanical and chemical action. It creates and

maintains space in the sulcus due to optimal characteristics of its viscosity which is

mainly due to its kaolin component. It achieves hemostasis due to the presence of

aluminum chloride. Time taken for retraction is 2 minutes and sulcus widening

achieved is 0.5mm. In recent years, the clinical applications in dental prosthetics have

undergone protocol changes regarding the new technologies and methods made

available by scientific research. Impression making is an important technical step in

the overall procedure of creating a successful prosthetic object. Because of the

enormous variability of clinical cases, it is not possible to use a single method or

impression material for fixed prostheses and therefore each operator is confronted

with numerous techniques – both conventional and innovative – and must be able to

adapt the most suitable one to the specific clinical case. In order to obtain correct

retraction of the gingival margins, the ideal condition is a state of optimum

periodontal health, ascertained in advance. However, each operator must deal with the

Introduction

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risk of gingival recession, a major problem which may cause work delays or even

functional and esthetic failure, meaning the prosthesis must be re-made7.

The advantages with Expasyl is that this material is Non-traumatic, it is a

conservative method of temporary gingival retraction, Easy and fast application

directly to the sulcus without pressure or packing making it comfortable to the patient,

Extensive rinsing is not required due to absence of haemostatic chemicals that could

contaminate impression site, it provides Outstanding retraction for perfect

impressions22

.

A new retraction material (Merocel, Merocel Co., Mystic, Conn.) was recently

proposed for dentistry to displace gingival tissue without tissue damage before

impression making. Merocel retraction strips are a synthetic material that is

specifically and chemically extracted from a biocompatible polymer (hydroxylate

polyvinyl acetate) that creates a netlike strip without debris or free fragments.

Merocel retraction material is chemically pure, easily shaped, remarkably effective for

absorption of intraoral fluids such as blood, saliva, and crevicular fluid, soft and

adaptable to the surrounding tissues, free of fragments, without debris, and not

abrasive.

Merocel retraction material was selected because it is an absorbing, haemostatic

material commonly used in otorhinolaryngic, gastric, thoracic, and otoneurosurgical

procedures.

This invivo study thus intends to compare the efficacy of three retraction methods that

is conventional retraction cord Expasyl (gingival retraction paste) and Merocel strip

Aims and Objectives

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AIM:

This comparative study aim to determine whether the Expasyl are able to displace the

gingival tissue in comparison with polyvinyle acetate strip and conventional retraction

cords

OBJECTIVES:

The key objectives of this study includes

1) To determine the amount of gingival retraction produced by cord;

2) To determine the amount of gingival retraction produced by the strip;

3) To determine the amount of gingival retraction produced by the Expasyl

4) To compare the amount of retraction produced by cord, Expasyl and Merocel

strip

Review of Literature

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REVIEW OF LITERATURE:

Goharkhay K, et al8 in the year 1995 had orchestrated an invitro study on effects on

oral soft tissue produced by a diode laser. This investigation determined incision

characteristics and soft-tissue damage resulting from standardized incisions using a

wide range of laser modes and parameters of a diode laser at 810 nm. For this

investigation, 17 fresh pig mandibles were used. Six standardized incisions per laser

parameter combination, 3 cm in length, were made in the oral mucosa parallel to the

border of the mandible. Three incisions per parameter were positioned 5 mm below

the gingival margin, and three in the thicker soft tissue 5 mm from the lower border of

the mandible. A total of 198 incisions was made. Histologic examinations were

performed to verify vertical and horizontal tissue damage as well as incision depth

and width. Statistical analysis was done. The study concluded that the remarkable

cutting ability and the tolerable damage zone clearly show that the diode laser is a

very effective and, because of its excellent coagulation ability, useful alternative in

soft-tissue surgery of the oral cavity.

Asbjorn Jokstad9, in 1999 has studied the clinical trial of gingival retraction cords.

Clinicians were unable to detect any clinical advantages of using epinephrine

impregnated gingival retraction cords compared with aluminium sulphate cords.

Smeltzer M10

, in 2003 had done an investigation on an alternative way to use

gingival retraction paste. Here the author says that Expasyl retraction paste is an

effective and tissue-friendly product designed as an alternative to retraction cord

placement for hemostasis. The manufacturer’s instructions indicate that the

mucogingival retraction paste is best expressed into a dry field. This is not always

achievable, and some difficulty arises while trying to place Expasyl in a wet field.


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Simply place soft cotton pellets over the area after expressing the material and

“condense” them with gentle finger pressure. Cover the area with gauze and allow the

patient to close the mouth while keeping the area dry and isolated. Wait two or three

minutes or, in cases of heavy bleeding, a longer time (about five to seven minutes).

Moisten the cotton with water before removing it, and then water-spray or microbrush

away the paste. Use of chlorhexidine in the microbrush also cleans the preparation.

Thus this investigation concluded that this procedure is useful because it does not

cause excessive trauma to delicate tissues. Also, it generally prevents the need to

excise or electrocauterize additional tissue, and the patient perceives the process as

gentle.

Gherlone E et al7, in the year 2004 had done a research on The Use of 980-nm Diode

and 1064-nm Nd:YAG Laser for Gingival Retraction in Fixed Prostheses. The aim of

the present study was to evaluate the tissue retraction and gingival healing in pulsed

laser (diode 980 nm and Nd:YAG 1064 nm lasers) gingival retraction in comparison

with the conventional mechanical or surgical techniques (double cord and

electrosurgery). A group of 103 adult patients scheduled for fixed and implant

prosthetic rehabilitation was recruited, and four impression techniques were

compared: the double cord technique, the electrosurgery technique, the 980-nm diode

and the 1064-nm Nd:YAG laser technique. Patient were randomly placed into four

groups according to impression-taking technique. Thirty impressions were taken in

each group. Statistical analysis was done. This study highlighted the lower

traumaticity of the laser-assisted sulcus conditioning (980-nm diode and Nd:YAG) on

the periodontal structures, as compared with conventional (mechanical and surgical)

techniques. Based on the present results, it can be concluded that the laser can be a

valuable tool for obtaining anatomical information for fixed prostheses, and it is


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capable of yielding correct results with maximum respect for the anatomy of the oral

tissue. In addition, during impression taking, 980-nm diode laser may exhibit a higher

hemostatic capacity than the Nd:YAG laser.

Arthur Scott11

, in the year 2004 had conducted a study on Use of an erbium laser in

lieu retraction cord. The two-cord retraction technique is used for troughing around a

crown to achieve biologic width. This technique can cause significant discomfort for

the patient and offers several potential clinical disadvantages for the dentist, of which

unpredictable tissue recession is the most significant. The clinical case presented in

this article compares the use of the standard two-cord retraction technique with that of

a 2,760 nm erbium-class dental laser to determine which method achieves an accurate,

easily readable impression while respecting the biologic width. Troughing for

impressions to complete indirect restorations can be accomplished easily with the

Er,Cr:YSGG laser. This technique eliminates the necessity for packing cord and will

minimize or eliminate any postoperative discomfort the patient may experience as a

direct result of retraction cord placement. It also avoids possible recession that would

result from excessive placement pressure by using a cord that was too thick and

leaving it in place for an extended period. In addition, the laser makes it simpler to

provide an impression trough when teeth are extremely close while reducing the

potential for tissue tears in these close areas. Thus this study concludes that, using an

erbium laser to achieve the trough prior to placing an indirect restoration results in

little or no postoperative discomfort for the patient; in addition, the erbium laser

reduces intraoperative complications related to tissue recession and patient discomfort

while providing consistently accurate impressions.

Yang J et al12

, in 2005 had orchestrated a study on developed injection-type gingival

retraction material. The aim of this study was to investigate the clinical outcomes with


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a newly developed non-aluminum chloride-containing injection-type retraction

material in terms of gingival retraction, gingival recession, and patient comfort and

also to compare it with 2 other commercial retraction materials. These 3 materials

were randomly applied to 3 unprepared maxillary incisors of 8 periodontally healthy

young individuals. Impressions were made with polyvinyl siloxane impression

material before retraction, immediately after retraction, and 14 days after retraction.

The duplicated stone models were subjected to a 3-D laser scanning device to

estimate the width of the retracted sulcus and gingival recession. Statistical analysis

was done and they concluded that this study indicates that the newly developed

injection-type retraction material ensures adequate sulcus retraction favorable for

making impressions in the majority of clinical situations. Local anesthesia is not

required since the application of the material is painless. Gingival recession is

minimal, which makes the material suitable for gingival retraction of anterior as well

as posterior teeth. Based on the above results, the application of the newly developed

injection-type retraction material as a gingival retraction agent is clinically feasible.

Hamad KQ, et al13

, In 2008 had done clinical study on the effects of cordless and

conventional retraction techniques on the gingival and periodontal health. Dental

students (n560) with healthy gingival conditions were recruited – an expanding poly

vinyl siloxane material (Magic Foam Cords), a paste-like material (Expasyls), and a

conventional retraction cord (Ultrapaks) were applied on the buccal aspects of three

premolars of each subject. Probing depth, clinical attachment level, gingival index

(GI), plaque index, mobility, bleeding, and sensitivity were assessed at baseline, and

at 1 and 7 days after application. Data were analysed. And the study concluded that

that all retraction techniques caused an acute injury after 1 day of retraction, which

took 1 week to heal in the Ultrapak and the Magic Foam groups. The Expasyl group


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had the highest GI compared with others, and showed slower healing. Its use might

cause sensitivity in a small number of cases. The use of cordless techniques did not

require haemostatic agent to control bleeding during retraction.

Sushma Phatale, et al14

, in 2010 has studied effect of retraction materials on gingival

health: A histopathological study There is a significant association between retraction

materials and gingival sulcular epithelium. It can be stated that impregnated retraction

cord, may be used commonly but it needs proper tissue manipulation and is technique

sensitive. Newly advanced material in the form of retraction paste like Expasyl or

Magic Foam Cord was found to be better than cord as assessed histologically, it

respects periodontium

Ani A et al15

, in 2010 had done a study on New Zealand dentists’ use of gingival

retraction techniques for fixed prosthodontics and implants. This study aims to

identify the techniques most commonly used in New Zealand for gingival retraction

for impressions of natural teeth and implants in fixed prosthodontics. The participants

were dental practitioners. A questionnaire was mailed to all 1,705 members,

Practitioners were classified into four groups according to their time since graduation:

those who had qualified 1-10 years previously, between 11 and 20 years ago, between

21 and 30 years ago and over 31 years ago. In conclusion Dentists in New Zealand

undertake a considerable amount of fixed prosthodontic and implant work. Gingival

retraction around natural teeth is used commonly, while only a small number of

participants report using it for implants. A surprising finding was the relatively high

number of participants who reported using surgery for gingival retraction around

natural teeth.


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Szu V et al16

, in 2011 had done an invitro analysis on Effect of a cordless retraction

paste material on implant surfaces. This invitro study evaluated the effect of a

cordless retraction paste material, Expasyl, on Ti Unite implant surfaces. Three areas

of the fixtures were evaluated before and after contact with the retraction paste using

scanning electron microscopy to evaluate changes in surface topography and energy-

dispersive spectroscopy to identify any surface chemistry modifications. All implants

were equipped with a sterile abutment to facilitate their handling. A gingival

retraction paste, Expasyl was applied to three different areas on each implant: the

collar (C), the junction of collar and microthread (JC) and the microthread (MT)

itself, using a handgun applicator. . Each abutment had a distinct notch carved for

precise positioning of the retraction paste and consistent observation of the surfaces

exposed to Expasyl. Two exposure times were selected: one minute (Group 1) as per

manufacturer instructions and ten minutes (Group 2). Thus this invitro study

concluded that Even though minimal changes to the implant surface morphology and

composition were observed after Expasyl contact, a definitive conclusion cannot be

drawn due to the small sample size. Further research with test cultures using

osteoblasts and fibroblasts should be conducted to assess the biocompatibility of

Expasyl-exposed implant surfaces.

Krishna D Prasad et al17

, in 2011 has studied gingival displacement in

prosthodontics: A critical review of existing methods. They concluded that gingival

retraction holds an indispensable place during soft tissue management before an

impression is made. Several problems that can arise from poor marginal fit of fixed

dental prostheses can be prevented if the margins of prepared tooth are recorded after

adequate exposure by any of the above mentioned gingival retraction methods. The


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choice of technique and material depends on operator’s judgement of the clinical

situation apart

From availability and cost of the materials. Swift increase in research work in the

recent past leaves no option for a clinician, but to be updated and to possess optimum

knowledge to rationalize the use of materials and techniques that are employed for

gingival displacement in proximity to both teeth as well as implants.

Rupali Kamath et al2, in 2011 studied the

Advances in Gingival Retraction. Atraumatic gingival tissue management for

impression making provides greater patient comfort during and after impression

making. During restorative procedures, it is incumbent upon clinicians to consider the

advantages and limitations of each method in individual case and patient, and to strive

for minimally invasive methods that optimize the procedural site for impression

making and restoration placement.

Ateeq P et al18

in 2011 had proposed a study on Conventional and New Techniques

in Gingival Displacement. Gingival displacement is an important procedure in the

fabrication of indirect restorations in fixed partial dentures including inlays, crowns,

veneers etc. These restorations have their cervical margins placed either at the level of

the gingiva or subgingivally for esthetic reasons. Failure to record the finish line

accurately results in compromised marginal integrity. It is found that inadequate

gingival displacement is the most common cause of this. This study highlights the

various techniques to achieve satisfactory gingival displacement by conventional

techniques as well with the use of newer available materials to achieve the same. Thus

the author concludes that gingival displacement is an important procedure with

fabricating indirect restorations. It is a relatively simple and easy procedure when


Page 13

dealing with healthy gingival tissue. The most common and widely used technique for

gingival displacement is the use of displacement cords soaked with a hemostatic

medicament. There are several techniques that are safe and efficacious; however no

scientific evidence has established the superiority of one technique over the other.

Shujaulla S et al19

, in the year 2012 had done a review on gingival tissue retraction.

This review article attempts to describe the various methods of gingival tissue

retraction. Physical displacing of the gingival tissue was one of the first methods for

insuring adequate reproduction of the prepared finish line. There is no ideal agent for

gingival retraction and therefore it is considered worthwhile to explore new chemical

agents. Aluminum chloride solution (15% and 25 %): It is one of the most commonly

used chemical. A 10 min. application is usually sufficient. Ferric sulfate (Monsel's

solution), It is advocated for use in gingival displacement. It is slightly more effective

than epinephrine in gingival displacement. The recommended time of use is 3

minutes. Expasyl is a unique paste system specifically designed for gingival retraction

that ensures suppression of gingival margin and drying of the sulcus. It displaces the

tissue similar to traditional retraction cord. The aim of this system is to detach the

marginal gingivae without injuring the epithelial attachment. The force exhibited by

the Expasyl is still nearly 50 times less than that of single and the double cord

technique. Expasyl is injected into the sulcus at approximately 2mm/second. It is left

in place for approximately 1 to 2 minutes. Thus the author concludes that there are

various methods for gingival tissue retraction. As such there is no specific method to

be followed for gingival tissue retraction. Depending on the type of clinical case and

the other related factors like accessibility, age, systemic disease etc the method for

gingival tissue retraction may be chosen.


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Nozawa K and Ito K20

, in 2012 had done a case report study on Intentional Gingival

Retraction with Provisional Direct Restoration: A Novel Approach to Facial Crown

Lengthening. This case report describes a novel approach for facial crown lengthening

of single teeth using intentional gingival retraction and provisional direct restoration.

After administration of anesthesia, facial bone sounding was performed. Gingival

retraction cords were pressed into the connective tissue attachment from the mesial to

the distal line angle. A provisional direct restoration was then performed. These

procedures were repeated until an ideal gingival outline was achieved. Crown

lengthening procedures are performed to improve excessive gingival display and to

expose sound tooth structures. Inadequate tooth structures, subgingival fracture lines,

and subgingival carious and non-carious cervical lesions are indications for exposure

of sound tooth structures. Forced eruption with fiberotomy is performed in the coronal

direction. The apically positioned flap procedure with osseous resection is performed

in the apical direction. After this surgery, hard- and soft-tissue remodeling results in

long-term free gingival growth. During a 12-month wound-healing period, facial and

interdental marginal gingiva change at different rates.5It is thus difficult to determine

the correct timing of subgingival crown placement. Statistical analysis was done.

Thus this study conluded that Intentional gingival retraction with provisional direct

restoration appears to be useful for facial crown lengthening of single teeth in

periodontal biotypes with thin bone.

Glenn A21

, in the year 2012 had conducted a study on Crown troughing with the 810

nm diode laser. two vital keys to the successful integration of laser troughing are:

adequate magnification for both the preparation of the tooth and the use of the laser ,

and the judicious use of lower power settings on the diode laser the initial gross

reduction of tooth structure is completed and the properly stripped, cleaved and


Page 15

initiated quartz fiber tip is extended just into the gingival sulcus subgingivally around

0.5–1.0 mm. Circumferentially the laser is moved with small, deft and light brushlike

strokes around the preparation. These back and forth strokes create a slight distention

of the tissue away laterally from the margin of the preparation. This lateral distention

is not intended to lower the height of the tissue in an apical direction like a

gingivectomy would, but simply to create a “moat” that separates tooth from soft

tissue. This separation allows for room for the light-body or extra-light-body VPS

impression material to capture details of the margin location. The total time for the

troughing circumferentially should be around 45 to 90 seconds. Thus concluding the

above cases and techniques are intended to demonstrate how laser troughing with the

810 nm diode laser can be used as an alternative to soft tissue management for

indirect prosthodontic procedures in both the anterior and posterior dentition. With the

increased number of clinicians now purchasing soft tissue lasers for gingival

recontouring and for tissue troughing, the need for detailed clinical treatment

protocols for these simple, safe and desirable procedures exists.

Gupta A et al5, 2013 in the year had conducted a research on Clinical Evaluation of

Three New Gingival Retraction Systems. The purpose of this study was to evaluate

the clinical efficacy of 3 new gingival retraction systems; Stayput, Magic foam cord

and expasyl, on the basis of their relative ease of handling, time taken for placement,

hemorrhage control and the amount of gingival retraction. The three gingival

retraction systems were used on the prepared abutments randomly, such that each

combination is repeated ten times. The time taken for placement of each retraction

system was recorded in seconds. Smooth rounded flexible measuring strip with 0.5

mm grading was used to measure sulcus depth before retraction and after retraction.

The measurements recorded in between two consecutive calibrations were considered


Page 16

as 0.25 mm. The horizontal retraction was measured on polyether impressions made

before the retraction and after retraction. Statistical analysis was done and the study

concluded that Magic foam cord can be considered more effective among the three

retraction systems used in this study, as it has taken less time and was easier in

placement, attained good amount of retraction and induced minimal bleeding on

removal compared to stay-put retraction cord.

Cooper K et al22

, had proposed a study in the year 2013 on Effect of a cordless

retraction paste on titanium surface: a topographic, chemical and biocompatibility

evaluation. Seventy-two sterile titanium disks were used. A gingival retraction paste

(Expasyl was applied on the surface of the disks using a handgun applicator. Minimal

alterations to surface morphology after contact with Expasyl (Acteon) were observed

in SEM images. The only change was observed at ×5000 magnification, where

“white” particles were visible on the surface. Finally the study concluded that

Chemical analysis indicated the presence of silicon after application of Expasyl.

Exposing the titanium disks to Expasyl did not affect their viability.

Shivashakthy et al1 in 2013 orchestrated a comparative study on the efficacy of

gingival retraction using polyvinyl acetate strips and conventional retraction cord. Ten

patients in good general health were selected for the investigation. Fourteen teeth

(maxillary anterior) were selected. Retraction systems used in this study were

polyvinyl acetate strips and plain retraction cord. The study was done using two

groups group a (plain retraction cord) and group B (polyvinyl acetate strips). In group

a retraction was done using retraction cord and after a two week time interval the

other material was tested. In the other group B the order of retraction material used

was reversed. A 2 mm thick polyvinyl acetate strip was inserted around the tooth

using cord packer. After two weeks the retraction was done using conventional plain


Page 17

retraction cords, which were packed dry into the sulcus without any chemicals. Thus

the study concluded that the displacement produced by the strips is significantly more

when compared to conventional cord. This conclusion was based on the fact that the

strips were free of fibers, fragments or debris when examined after use. Hence the

material was considered safe for gingival health.

Anupam et al23

in 2013 conducted a study to evaluate the efficacy of two gingival

retraction systems on lateral gingival displacement. A total of seventy two

preparations for indirect fixed restorations were performed (thirty six each for

ultrapak and stay-put). Cords were placed in the gingival sulcus with use of a cord

packer, and left in situ for 10 min before making the impression. The cords were

removed from both side of the same arch and was followed by impression making

using double mix putty wash technique. Data was analyzed. Thus the study concluded

that mean gingival retraction with stay-put was higher as compared to that in ultrapak.

This could be due to provision of thin copper wire within stay-put retraction cord

which rendered retentive ability in sulcus, consistency, ease of packing and less cord

fraying.

Krishna et al4 in 2013 performed a study on laser gingival retraction. 20 abutment

teeth were indicated for porcelain fused to metal crowns with subgingival shoulder

and lingual supragingival chamfer finish line. All abutments were root canal treated,

out of 20 selected abutments, 10 abutments were anteriors and the remaining 10 were

posterior teeth. All selected abutments had healthy gingival, without a periodontal

pathology. A diode laser with a fibre optic tip was used for the study. After tooth

preparation retraction procedure was carried out by passing laser optic fibre in contact

mode along the gingival sulcus, to remove the sulcular epithelium. Laser energy was

delivered which had a wavelength of 980nm and power of 0.8W in continuous mode.


Page 18

Laser tip was inserted 1 mm into the gingival sulcus, to facilitate an accurate

recording finishline. After completing the retraction, impressions were made by using

addition silicon impression material and models were obtained from type IV stone.

On these stone models, mesiobuccal, midbuccal and distobuccal regions were selected

for measurement of retraction. Two points were marked, one on finishline and the

other one on crest of marginal gingival in three regions, for each abutment. Gingival

retraction was assessed by measuring the distance between two points by using tool

Makers Microscope. Data was analysed. Thus the study concluded that, when

compared to conventional techniques, lasers offer certain advantages such as lesser

operating time and lesser collateral heat generation, with good hemostasis and patient

comfort.

Bennani et al3 in 2014 conducted a study on comparison of pressure generated by

cordless gingival displacement materials. A 5 5 2-mm chamber was made from

silicon on 4 of the 5 surfaces to simulate a crevicular space. Four materials were

tested: Expasyl, Expasyl new, 3M ESPE astringent retraction paste ARP and magic

foamcord. Expasyl and Expasyl new were injected into the chamber with an Expasyl

power applicator motorized gun with a 1.5-mm-diameter injection tip at 20000 rpm.

The 3M ESPE ARP paste was injected into the chamber with manual applicator.

Magic foam cord was injected into the chamber with a manual applicator. The

pressure was recorded 1000 times per second with a recording system with the

software chart, version 5.After each test, the silicone and stone compartments were

separated and the material was removed. Each group was tested 15 times, and the

median maximum injection pressure (kpa) and median post injection pressure (kpa)

were calculated. The post injection pressure was determined by averaging the median

pressure values from the point at which the applicator was withdrawn to 1 minute


Page 19

after withdrawal. Investigated the pressures exerted by 4 different cordless gingival

displacement materials .Statistical analysis was done. Thus the study concluded that

Expasyl new and Expasyl generated the highest pressures and, therefore, could be the

most effective gingival displacement materials. This was due to the fact that Expasyl

injection had kaolin-based material which has high viscosity.

Acar et al24

in 2014 performed a study on clinical comparison of cordless and

conventional displacement systems regarding clinical performance and impression

quality. A total of 252 participants requiring single-unit indirect partial fixed dental

prosthesis were selected and 4 displacement methods were evaluated in this study.

The displacement methods used were nonimpregnated displacement cord (NIC),

aluminum chloride impregnated displacement cord (IC), 15% aluminum chloride

displacement paste with displacement cap (PC), and aluminium chloride impregnated

displacement cord with displacement paste and displacement cap (ICPC). The study

included crown preparation for metal ceramic and ceramic restorations. Margins were

positioned 1 to 2 mm subgingivally. A blunt instrument was used to gently pack the

cord into the sulcus. Each cord remained in place for 15 minutes and was removed

while wet. Before making the impression the tooth was rinsed, and a gentle blast of

compressed air was applied. Impressions were made using polyether impression

material. Statistical analysis was done. Thus the study concluded that dilatation was

best in group ICPC and worst in group NIC. This was due to the use of aluminum

chloride with displacement cord which decreased the incidence of bleeding after cord

removal and increased impression quality. The use of displacement paste and cap

technique was easy and time efficient and it caused less bleeding than the

impregnated displacement cord application. Thus the use of displacement cord, paste,


Page 20

and cap together had advantages for bleeding, dilatation, and impression quality,

although it was time consuming and difficult.

Baba N et al25

had performed a study on Gingival Displacement for Impression

Making in Fixed Prosthodontics. The clinical success and longevity of indirect

restorations depend on the careful and accurate completion of several procedures. One

of the challenging procedures is management of the gingival tissues and gingival

esthetics. The goal for management of gingival tissues and gingival esthetics is to

maintain the normal appearance of healthy gingiva. Achieving this goal requires

optimal health before treatment and minimal trauma during treatment. The best way

of optimizing health and minimizing trauma is to avoid contacting the gingiva with

restorative materials. However, for esthetic or functional reasons, restoration margins

are frequently located within the gingival sulcus. One disadvantage of subgingival

margins is that they have the tendency to increase the potential for periodontal

problems (gingival inflammation). However, periodontal health can be maintained in

the presence of subgingival margins but it requires careful execution of the clinical

procedures and well-fitting, properly contoured crowns. Appropriate, reversible,

gingival displacement and tissue management are required.

Ahmed S and Donovan T26

, in 2015 had conducted a study on gingival

displacement: Survey results of dentists’ practice Procedures. The purpose of this

study was to learn the different gingival displacement techniques that are currently

used by dentists in their practice and to compare the current concepts of gingival

displacement with previously published articles. A survey of questions pertaining to

gingival deflection methods was distributed as part of continuing education (CE)

course material to dentists attending CE meetings in 7 states in the U.S. and 1

Canadian province. The questions in the survey inquired about initial patient


Page 21

assessment procedures, various gingival displacement methods, and type of

displacement method currently used in their practice. The dentists’ knowledge and

assessment of systemic manifestations, such as increased heart rate and blood

pressure, syncope, palpitation, and cardiac arrest, was also determined. Statistical

analysis was done. Thus the study concluded that A high percentage of dentists (92%)

continue to use gingival displacement cords and medicaments to expose the cervical

margins of tooth preparations. The percentage of practitioners using epinephrine has

decreased from 79% in 1985 to 31.3% in 2014. A significant number of practitioners

(28%) reported using cordless techniques for gingival displacement.

Stuffken M and Vahidi F27

, in the year 2015 had orchestrated a study on

Preimpression troughing with the diode laser. The purpose of this pilot study was to

clinically monitor and compare the regeneration of the gingival tissue by using 2

methods of gingival displacement in the same participant: the mechanical-chemical

technique with double cords impregnated with aluminum chloride and th 810 nm

diode laser. A total of 6 participants needing 2 crowns on natural teeth were included

in this study. Four white, 1 African American, and 1 Asian participant were selected,

ranging from 18 to 75 years of age. They all required 2 crown restorations on natural

teeth. The first visit involved preparation of the teeth, the type of preparation was a

deep chamfer placed approximately 0.5 millimeter apical to the gingival margin. For

the double-cord technique, a number 000 cord soaked in 5% aluminum chloride was

placed at the base of the gingival crevice, followed by a soaked number 1 cord. For

the second preparation, the gingiva was troughed using the 810-nm diode laser. The

procedure always began with the laser at the lowest power to displace the tissue. The

diode laser was set at a continuous wave of 0.7 W and, depending on the tissue, the

power could be increased to a maximum of 2W if necessary. A device was made that


Page 22

would function as a fixed reference point for the measurements at different time

intervals. A notch was created on the device to position the digital ruler between the

occlusal notch and the free gingival margin to measure the distances. The

measurements were recorded for each patient before displacement of the gingiva and

at the time of cementation of the definitive crowns. The patients were followed at 1

week, 3 weeks, and 8 weeks after cementation of the definitive crowns. Statistical

analysis was done. Thus this study concluded that Eight weeks after the cementation

of definitive crowns, comparable recession was found with mechanical chemical

gingival displacement and a diode laser. The amount of recession may not be

clinically significant

Safari S et al28

, in the year 2016 had put forth a study on Gingival Retraction

Methods for Fabrication of Fixed Partial Denture. Fixed dental prosthesis success

requires appropriate impression taking of the prepared finish line. This is critical in

either tooth supported fixed prosthesis (crown and bridge) or implant supported fixed

prosthesis (solid abutment). If the prepared finish line is adjacent to the gingival

sulcus, gingival retraction techniques should be used to decrease the marginal

discrepancy among the restoration and the prepared abutment. Accurate marginal

positioning of the restoration in the prepared finish line of the abutment is required for

therapeutic, preventive and aesthetic purposes. Thus the study concluded that gingival

retraction techniques can be classified as mechanical, chemical or surgical. In this

article, different gingival management techniques comprising non-medicated cords,

medicated cord, cordless techniques, astringent hemostatic agents, gingival retraction

paste, vasoconstrictive agents, lasers, rotary curettage, electrosurgery were discussed.

Also, gingival retraction in dental implants and digital impression were discussed.


Page 23

Lahoti K S29

, in 2016 had conducted a study on effect of various chemical agents

used in gingival retraction systems on smear layer. The purpose of this study was to

determine the effect of three different chemical agents used for gingival retraction

systems on smear layer. Four human premolars were prepared using air-rotor with

air‑ water spray to receive full crown restoration. Three of them were treated with

21.3% aluminum chloride for 10 min(Group A) , 0.05% oxymetazoline hydrochloride

for 10 min(Group B), and expasyl for 2 min( Group C), respectively. One sample was

left untreated. All the samples (treated and untreated) were processed by scanning

electron microscope (SEM). Processed samples were examined under SEM at ×2400

to evaluate the effect of chemical agents on smear layer. Statistical analysis was done.

Thus the present study concluded that From the SEM examination, it is evident that

Group B, i.e., knitted cord impregnated with 0.05% oxymetazoline hydrochloride

produced no alteration to smear layer followed by minimum alteration by Group C,

i.e., expasyl paste retraction system. Complete removal of smear layer with etching of

dentin was demonstrated in Group A sample i.e., knitted cord impregnated with

21.3% aluminum chloride. Hence, showing that oxymetazoline hydrochloride and

expasyl are kind to smear layer and tooth structure.

Chaudhari J30

, in 2016 had proposed an invivo study on Comparative evaluation of

the amount of gingival displacement produced by three different gingival retraction

systems. The study was designed to clinically evaluate efficacy of newer retraction

agent tetrahydrozoline with two widely used retraction systems i.e., Expasyl retraction

system and medicated retraction cords on basis of amount of gingival retraction. 30

subjects were selected according to inclusion and exclusion criteria. Maxillary

Impressions were made with irreversible hydrocolloid for all subjects. Tray material

was used for making the special tray. Latin Block Design was used in the Study to


Page 24

avoid tissue fatigue. Retraction was done with aluminium chloride; Tetrahydrozoline

and Expasyl according to Latin block design. Impressions were poured with die stone.

Casts were retrieved and sections were made with die cutter. 3 mm thin slices were

obtained. Each slice was used to measure the amount of retraction under

stereomicroscope under 20x and images were transferred to image analyser. Statistical

analysis was done. Thus the study concluded that all three displacement systems

namely (aluminum chloride, tetrahydrozoline, expasyl) show clinically and

statistically significant amount of displacement. Among the three displacement agents

tested, displacement cord with aluminum chloride showed the maximum

displacement. Expasyl shows the least amount of displacement. Considering the result

that displacement cord with the tetrahydrozoline produce comparable displacement as

aluminum chloride and can be a good alternative to it.

Raghav D et al6 in the year 2016 had proposed a study on a comparative clinical and

quantitative evaluation of the efficacy of conventional and recent gingival retraction

systems. Gingival deflection techniques can be classified as mechanical,

mechanochemical, surgical, or any combination. Comparative evaluations of gingival

retraction systems are done rarely mainly because there is no consensus on the

evaluation criteria. Therefore, this study aimed to evaluate the efficacy of three

different gingival retraction systems, i.e., Magic Foam Cord, Expasyl paste, and

aluminium chloride-impregnated retraction cord. Following impressions following

impressions. Optical microscope attached to axiovision was used to measure the width

of gingival sulcus. Four impressions were made for each participant at the time

interval of 8 days-one without gingival displacement and the rest three after gingival

displacement using three different retraction systems. The sulcus width or amount of

gingival retraction was measured as the distance from the tooth to the crest of the


Page 25

gingiva in the horizontal plane. Thus this study concluded that Though the maximum

retraction was produced by aluminium chloride-impregnated retraction cord and even

there were statistically significant difference in the width of retracted gingival sulcus

among three systems except between Expasyl paste and impregnated retraction cord,

which was insignificant but enlargement achieved in all the three systems was more

than the minimum required. Advantages with Expasyl paste and Magic Foam Cord

over the retraction cord were their ease of application, painless, quick, and without

agony to the patient.

Materials and Methods

Page 26

MATERIALS AND METHODS

ARMAMENTARIUM

1. Mouth mirror, William’s periodontal probe, and tweezers.

2. Surgical gloves, mouth mask.

3. Cotton rolls

4. Scissors- straight and angled

5. Cord packer (Hu-Friedy, USA)

6. Cheek retractor

7. Digital Vernier caliper

MATERIALS

1. Conventional retraction cord (Ultrapak, Ultradent, USA)

2. Expasyl paste (Kerr)

3. Merocel strip (Mystic, Conn)

METHOD OF DATA COLLECTION.

INCLUSION CRITERIA

Not less than 18 year of age

Preparation needed for full coverage restoration

Sound gingival end periodontal health of the abutment teeth

Abutment teeth of normal size and contour (no developmental anomaly or

regressive age changes)

Abutment teeth selected in maxillary anteriors.

EXCLUSION CRITERIA

Tipped , tilted or rotated abutment teeth

Any kind of gingival pathology.


Page 27

The study was done using three groups, the same patients served for all the groups. In

one group (Group A) the retraction was done using the retraction cord (Ultrapak,

Ultradent, USA) at the time of tooth preperation and after a two week time interval

patient recalled for metal trail and the Merocel (Mystic, Conn) was tested in the other

group (Group B) then again after two week time interval patient recalled for

cementation and expasyl was also tested. In (Group C).

For the clinical procedure, the tooth was prepared with a equi-gingival level without

retraction of the gingival sulcus. Clinical measurements were initially recorded





vernier caliper.







intracrevicular space were removed and the measurements repeated.

After two weeks at the time of metal trial the retraction was done using conventional

plain retraction cords, which were packed dry into the sulcus without any chemicals

using “000” cord first followed by “0” (double cord technique). The measurements

were recorded as before.


Page 28

After two weeks again at the time of cementation retraction is done using Expasyl and

measurement were recorded as before All the measurements were done by a single

operator.

METHODOLOGY

A total of twenty patients between the age group 18-40 years who reported to the

department of prosthodontics, in Farooqia Dental College and hospital and were in

need of fixed partial dental prosthesis or a crown formed the study group. The study

was approved by the ethical committee of Farooqia Dental College and Hospital and

all the patients were provided with an informed consent. The criteria for case selection

included patients with a sulcus depth of 1-1.5 mm in maxillary anterior region,

abutment teeth of normal size and contour. Individuals having similar gingival

biotype, restorations requiring equi-gingival finish lines and patients with no healthy

gingiva. The preparation design protocols were followed based on “Fundamentals of

tooth preparations” by Herbert T. Shillingburg. All selected abutments had healthy

gingiva, without a periodontal pathology. A shoulder finish line was given to the

preparation according to the type of restoration indicated.

Three different gingival displacement methods were evaluated in this study; viz

conventional retraction cord, a cordless technique and merocel strip. All the three

retraction methods were checked on the same abutment tooth with similar sulcus

depth and each procedure done over a period of two weeks interval. Once the

abutment tooth preparation was completed, the retraction was done using the cordless

technique first, two weeks following this, the same abutment tooth was subjected to

retraction using the conventional retraction technique and after a period of two weeks,


Page 29

retraction was again carried out on the same abutment tooth using the Merocel strip

respectively.

Methods of gingival retraction

1. Gingival Retraction using cordless (Expasyl) technique.

Expasyl is a paste for temporary gingival retraction that ensures separation of the

marginal gingiva and drying of the sulcus. The material is supplied in capsules

(cartridges), and comes with a preformed gun-type of device into which the capsule

has to be placed and then the material is expressed. Gingival sulcus of the abutment

tooth was rinsed with water, the retraction paste was then slowly injected into the

sulcus (2 mm/s) with the tip parallel to the long axis of the teeth. The point of the

cannula must create a closed space between the tooth and the marginal gingiva.

Clinically, the complete filling of the sulcus was discerned by a slight blanching of

the gingival marginal area. It was kept in place for two minutes. It was easily visible

because of its color. After which, it was removed by air and water spray. The

measurement was recorded linear from the prepared finish line to the free gingival

margin using digital Vernier caliper.

2. Gingival retraction using conventional retraction cord (Ultrapak).

The use of gingival retraction cords which was non-impregnated is supposed to be

safe and effective. The gingival sulcus, was rinsed, dried, and isolated with cotton

rolls. The retraction cord “000” was cut to the required length and packed into the

sulcus with a cord packer and then cord size “0” is placed using cord packer and was

left in place for ten minutes. The placement started at the interproximal gingival

crevice, where there was usually more tissue, and was continued circumferentially.


Page 30

After the required period, the retraction cord was moistened with water spray and

removed, and the gingival sulcus was washed and dried.

During each of the procedure Clinical measurements were initially recorded





Vernier caliper.

3. Method of gingival retraction using Merocel strip







intracrevicular space were removed and the measurement was recorded linear from

the prepared finish line to the free gingival margin using digital Vernier caliper.

Sample Size Estimation

Page 31

SAMPLE SIZE ESTIMATION

The sample size was estimated using the formula:

n = (Zα/2+Zβ)2 ×2(σ)2/ d2

Where,

Zα/2 = 1.96 at 95% Confidence Interval

Zβ = 0.842 at 80% power,

σ2= Population variance = 50

d = Difference detected in previous study = 5.3

n = (1.96 +0.842)2×2×50/ (5.3)2=19.95 ≈ 20

According to the value obtained using the formula, the n value calculated for

the study was 19.95. But for easy distribution in the subgroups, the sample

size estimation was kept as 20.

Results

Page 32

RESULT

The collected data were analysed using one way ANOVA and post hoc test with

p<0.05 indicating significant difference between the variables.

The statistical analysis of the collected data revealed that the conventional retraction

cord produced significant amount of gingival retraction [table 1,2,3]. The mean

gingival retraction value obtained for retraction cord, Expasyl and Merocel strip were

Table 1: values obtained by Vernier Caliper

SL.NO RETRACTION CORD

Facial M Facial C Facial D Palatal M Palatal C Palatal D

1 0.6 0.6 0.6 0.6 0.6 0.6

2 0.5 0.5 0.5 0.5 0.6 0.5

3 0.6 0.5 0.5 0.6 0.5 0.6

4 0.6 0.5 0.5 0.5 0.5 0.4

5 0.6 0.6 0.6 0.6 0.6 0.6

6 0.6 0.6 0.5 0.5 0.6 0.5

7 0.7 0.5 0.6 0.6 0.5 0.4

8 0.7 0.4 0.5 0.5 0.6 0.5

9 0.6 0.4 0.4 0.6 0.6 0.6

10 0.7 0.4 0.5 0.5 0.6 0.5

11 0.6 0.5 0.6 0.6 0.5 0.4

12 0.7 0.7 0.6 0.6 0.7 0.5

13 0.5 0.5 0.6 0.5 0.5 0.5

14 0.6 0.6 0.6 0.4 0.6 0.5

15 0.5 0.6 0.5 0.5 0.4 0.5

16 0.4 0.5 0.5 0.6 0.5 0.5

17 0.4 0.4 0.5 0.6 0.5 0.5

18 0.5 0.6 0.5 0.5 0.5 0.5

19 0.5 0.5 0.6 0.6 0.6 0.6

20 0.7 0.7 0.6 0.5 0.6 0.7

* M: mesial, C: center, D: distal.

Results

Page 33

Table 2: Value obtained by Digital Vernier Caliper

SLNO EXPASYL

Facial M Facial C Facial D Palatal M Palatal C Palatal D

1 0.5 0.5 0.6 0.5 0.6 0.5

2 0.4 0.5 0.4 0.4 0.6 0.4

3 0.5 0.4 0.3 0.5 0.4 0.5

4 0.4 0.4 0.4 0.4 0.4 0.4

5 0.5 0.5 0.5 0.5 0.5 0.5

6 0.6 0.6 0.4 0.4 0.5 0.4

7 0.5 0.4 0.5 0.5 0.4 0.4

8 0.7 0.4 0.3 0.4 0.6 0.5

9 0.5 0.3 0.3 0.5 0.5 0.5

10 0.6 0.4 0.4 0.4 0.5 0.4

11 0.5 0.5 0.5 0.5 0.4 0.5

12 0.6 0.6 0.5 0.5 0.6 0.4

13 0.4 0.4 0.5 0.4 0.4 0.5

14 0.5 0.5 0.5 0.4 0.5 0.4

15 0.4 0.5 0.4 0.5 0.4 0.5

16 0.4 0.4 0.4 0.5 0.4 0.4

17 0.3 0.4 0.5 0.5 0.4 0.4

18 0.5 0.5 0.4 0.4 0.5 0.4

19 0.5 0.5 0.4 0.4 0.5 0.5

20 0.6 0.6 0.5 0.5 0.6 0.6


Results

Page 34


SL.NO MEROCEL STRIP

Facial M

(mm)

Facial C

(mm)

Facial D

(mm)

Palatal M

(mm)

Palatal C

(mm)

Palatal D

(mm)

1 0.3 0.3 0.4 0.3 0.4 0.4

2 0.3 0.3 0.3 0.4 0.4 0.3

3 0.4 0.3 0.4 0.4 0.4 0.3

4 0.3 0.3 0.4 0.3 0.4 0.3

5 0.2 0.3 0.3 0.3 0.3 0.4

6 0.4 0.4 0.4 0.4 0.3 0.3

7 0.4 0.4 0.3 0.3 0.5 0.3

8 0.5 0.5 0.4 0.4 0.4 0.3

9 0.5 0.5 0.4 0.3 0.4 0.4

10 0.4 0.4 0.4 0.4 0.3 0.5

11 0.4 0.4 0.3 0.3 0.3 0.3

12 0.4 0.3 0.3 0.3 0.4 0.3

13 0.3 0.3 0.3 0.3 0.3 0.3

14 0.4 0.3 0.3 0.4 0.3 0.3

15 0.4 0.3 0.3 0.5 0.3 0.4

16 0.3 0.4 0.4 0.5 0.3 0.4

17 0.4 0.3 0.3 0.3 0.4 0.4

18 0.2 0.3 0.4 0.5 0.4 0.4

19 0.3 0.3 0.3 0.2 0.3 0.3

20 0.5 0.5 0.4 0.5 0.5 0.4


Results

Page 35

Table 4: Descriptive Statistics

Mesially on Facial side

Group Mean Std. Deviation N

Retraction cord .5800 .09515 20

Expasyl .4950 .09445 20

Merocel strip .3650 .08751 20


Center on Facial side



Expasyl .4650 .08127 20



Distally on Facial side



Expasyl .4350 .08127 20


Results

Page 36


Mesially on Palatal side



Expasyl .4550 .05104 20



Center on Palatal side


Retraction Cord .5550 .06863 20

Expasyl .4850 .08127 20

Merocel Strip .3650 .06708 20


Distally on Palatal side


Retraction Cord .5200 .07678 20

Expasyl .4550 .06048 20

Merocel Strip .3500 .06070 20

Table 10: Mean Retraction on each Material

Materials Retraction Cord Expasyl Merocel Strip

Mean Obtained 0.545mm 0.465mm 0.358mm

Results

Page 37

Graph 1: Showing maximum gingival displacement by Retraction cord followed

by Expasylcord and Merocel strip respectively.

1. The amount of gingival retraction produced by the cord is 0.545mm.

2. The amount of gingival retraction produced by the Expasyl is 0.465mm.

3. The amount of gingival retraction produced by the strip is 0.358mm.

4. Conventional retraction cord produced statistically significant gingival

retraction.


produced by conventional retraction cord is significantly more.


the displacement produced by Expasyl is significantly more.

0

0.1

0.2

0.3

0.4

0.5

0.6

GINGIVAL RETRACTION CORD EXPASYL MEROCEL STRIP

Result

AMOUNT OF RETRACTION (mm)

Discussion

Page 38

DISCUSSION

Fixed Partial Denture requires an accurate impression that records location of the

finish line of the prepared tooth and a portion of the apical tooth structure. Therefore,

it is necessary to effectively displace the free gingival margin. Also, Impression of the

teeth and the surrounding structures is of utmost important because it is neither

possible nor desirable to make patterns for fixed prosthesis directly in the mouth

Impression making for all fixed prostheses requires access to the prosthetic margin

while minimally traumatizing the tissue, so that clinicians can provide as much

clinical information as possible to the laboratory technician. This information allows

the technician to design the prosthesis to meet the criteria of the periodontium and

allow the gingival tissues to recover to their original state

The aim of this study was to clinically evaluate three gingival retraction techniques

relative to impression making in fixed prosthodontics in order to compare their

efficacy of retraction traumaticity to the periodontal tissues, and in terms of

establishing the preparation margin of the treated dental elements.5

This study investigated the effects of different retraction techniques on gingival

displacement. Three different displacement methods evaluated in this study were,

conventional retraction cord (Ultrapak, Ultradent, USA), a cordless technique

(Expasyl) and Merocel strip (Mystic, Conn). All the three retraction methods were

done on the same abutment teeth/crown in the maxillary incisors with similar sulcus

depth in an individual, with each procedure done over a period of ten days interval.

The advantages of a conventional retraction cord are that it is dark: it is dark in color,

to maximize contrast with the tissues, tooth and cord; it acts as an absorbent, to allow

Discussion

Page 39

the uptake of the liquid medicaments; and they are available in different diameters to

accommodate varying morphologies of gingival sulcus. Various haemostatic agents

with varying degrees of safety and effectiveness are available such as aluminium

potassium sulphate (Alum), aluminium chloride, epinephrine, zinc chloride, ferric

sulphate and sympathomimetic amines.

The disadvantages of conventional retraction cord are that it can be laborious, time-

consuming, can cause gingival bleeding, uncomfortable for patients in the absence of

anaesthesia, and when inappropriately manipulated, can lead to direct injury and

gingival recession. Use of a retraction cord has the risk of epithelial attachment injury,

pain during cord placement, sometimes requiring local anesthesia. They also require

high technical sensitivity and clinical skill.

In this present study conventional retraction cord showed better gingival displacement

than Expasyl because it acted as a good absorbent which allowed the uptake of oral

fluid and expand resulting in subsequent gingival displacement.

The use of injectable matrix (Expasyl) for gingival retraction presents an atraumatic

option for clinicians. There is no risk of laceration, as the material is injected in a

kaolin matrix into the gingival sulcus. The limitation of this injectable matrix arise

from the viscosity of the injectable matrix, which limits the force of retraction

offered.3 It has a specially formulated consistency which exerts moderated calculated

pressure on gingiva. It has both mechanical and chemical action. It creates and

maintains space in the sulcus due to optimal characteristics of its viscosity which is

mainly due to its kaolin component. It achieves hemostasis due to the presence of

aluminium chloride. Time taken for retraction is 2 minutes and sulcus widening

achieved is 0.5mm. The pressure exhibited is 0.1N/mm.2

Discussion

Page 40

The advantages with Expasyl is that this material is non-traumatic, it is a conservative

method of temporary gingival retraction, easy and fast application directly to the

sulcus without pressure or packing making it comfortable to the patient, extensive

rinsing is not required due to absence of haemostatic chemicals that could

contaminate impression site, it provides outstanding retraction for perfect

impressions.2

Here the mechanism of retraction does not involve any chemical reaction and the

material expands on setting displacing the gingiva. It does not damage the epithelium

The main disadvantage with Expasyl retraction material is that the amount of

displacement achieved will be less compared to conventional techniques although it

had advantages like less working time and patient comfort when compared to

retraction cord and merocel strip.

It is expensive, it is effective only under specific limited conditions, the paste

thickness makes it difficult for some evaluators to express it into the sulcus.22

Bennani et al, compared the pressure generated from cordless methods to Knitted

cords. Expasyl injection generated the least pressure and its pressure will be less in

reuse.12

The Merocel strips was selected for the study following the preliminary clinical study

by Marco Ferrari et al., who reported that the material had beneficial physical

properties like absorption of intraoral fluids, chemically pure and exerting moderate

pressure on the gingival tissue without requiring local anesthesia which ensured a

gingival displacement without damage [1,5]. Merocel is an absorbing, haemostatic

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3843446/#b1

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3843446/#b5

Discussion

Page 41

material commonly used in otorhinolaryngic, gastric, thoracic and otoneurosurgical

procedures.

Numerous studies have reported mechanical methods that involved the use of

retraction cords with or without medicaments to be the most effective, safe and easy

methods for tissue displacement. Hence, in this study, the retraction cord placed by

double cord technique was used as a control to compare the retracting efficacy of

Merocel and Expasyl.

All the cases in current study also demonstrated fluid free, haemostatic environment.

The haemostatic property might be attributed to the moderate pressure exerted by the

material placed in the sulcus and not because of the chemical composition.

However, use of Merocel material as a gingival retraction device carries some

limitations including it is difficult to secure the material in place during the process of

placement and retraction. The material found to be easily placed when it is dry than

when it is wet.

In this present study [table-1,2,3] shows conventional retraction cord showed better

gingival displacement than Expasyl because it acted as a good absorbent which

allowed the uptake of oral fluid and expand resulting in subsequent gingival

displacement.

Limitations of this study include the difficulty in placement of the Merocel material in

the gingival sulcus and the retraction when compared to expaysl and conventional

retraction cord (double cord technique) is less. And measurements can be taken after

impression made and on the poured cast using Tool Makers Microscope, so that more

accurate measurements can be obtained.

Conclusion

Page 42

CONCLUSION

Based on results of the study, the following conclusions were drawn:

1. Conventional retraction cord produced statistically significant gingival

retraction (p<0.001).


produced by conventional retraction cord is significantly more (p<0.001)


the displacement produced by the Expasyl is significantly more (p<0.001)

Summary

Page 43

SUMMARY

Need for the gingival retraction is to widen the gingival sulcus in order to provide

access for impression material to reach the subgingival margins and to record

adequately the finish line. It helps in obtaining the perfect die with accurate margins,

which helps in margin placement and contouring of the restoration. It helps in

blending of the restoration with the unprepared tooth surface. It also helps in

placement and finishing of the margins on the prepared tooth. During cementation it

helps in easy removal of cement without tissue damage. It helps the dentist in visually

assessing the marginal fit and any caries if present. To enhance access and to prevent

damage to the soft tissue during tooth preparation procedure, it may be desirable to

carry out some degree of gingival retraction prior to commencement of preparation.

The purpose of this invivo study was to compare the efficacy of amount of gingival

displacement obtained using a conventional retraction cord Expasyl (cordless

technique) and Merosel strip. The amount of gingival displacement was assumed by

measuring the distance between two points one on the finish line and the other on the

crest of marginal gingiva using digital Vernier caliper.

The study was conducted in 20 patients with good general and periodontal health

requiring fixed restorations for their maxillary incisors. The patients were divided into

three groups. In Group A the retraction was done using the retraction cord (Ultrapak,

Ultradent, USA), Group B using Merocel (Mystic, Conn) and Group C using Expasyl

in two weeks interval time.

The tooth was prepared with a supra-gingival level without retraction of the gingival

sulcus. Clinical measurements were initially recorded immediately before retraction

Summary

Page 44

on the buccal and palatal aspect at three points on each side that coincided with the

mesial line angle, distal line angle and at the deepest point on the preparation to the

crest of the free gingival margin. The measurement was recorded linear from the

prepared finish line to the free gingival margin using Digital Vernier Caliper.

Based on results of the study, Conventional retraction cord produced significant

amount of gingival retraction. When compared with the displacement produced by

Expasyl, the displacement produced by conventional retraction cord is significantly

more. When compared with the displacement produced by Merocel retraction strip the

displacement produced by the Expasyl is significantly more.

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Page 45

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Consent Form

Page 49

INFORMED CONSENT FORM

I ___________________, hereby acknowledge that my maxillary arch impression, pre

& post gingival retraction using (1.Expasyl / 2.merocel strip / 3. Conventional

Retraction Cord) is made and photographs are taken by DR.NAHAD ABDUL

NASER, Post-Graduate student in Dept. of Prosthodontics for his dissertation with

my consent. I also give his permission to carry out his study using my photographs

and the maxillary arch study models for the purpose of research. I am assured that my

privacy will not be violated under any circumstances.

I have understood the information about the research and I voluntarily agree to

participate in the research.

I hereby give consent to DR.NAHAD ABDUL NASER to proceed with the required

procedures for his study..

Signature of the Patient ________________

Date ______

Signature of the Doctor ________________

Date ______

Ethical Committee clearance letter

Page 50

Proforma

Page 51

PROFORMA

Slno Retraction cord

(mm)

Expasyl

(mm)

Merocel strip

(mm)

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

Master Chart

Page 52

MASTER CHART

BEFORE PROCEDURE

SLNO Facial M

(mm)

Facial C

(mm)

Facial D

(mm)

Palatal M

(mm)

Palatal C

(mm)

Palatal D

(mm)

1 0.1 0.1 0.1 0.1 0.1 0.1

2 0.2 0.1 0.1 0.1 0.1 0.1

3 0.1 0.1 0.1 0.2 0.1 0.1

4 0.1 0.1 0.1 0.1 0.1 0.1

5 0.1 0.2 0.2 0.1 0.1 0.1

6 0.2 0.2 0.1 0.1 0.2 0.1

7 0.1 0.1 0.2 0.1 0.2 0.1

8 0.3 0.2 0.1 0.1 0.2 0.2

9 0.1 0.1 0.1 0.1 0.1 0.1

10 0.1 0.1 0.1 0.1 0.1 0.1

11 0.1 0.1 0.1 0.1 0.1 0.2

12 0.2 0.2 0.1 0.2 0.1 0.1

13 0.1 0.1 0.1 0.1 0.1 0.1

14 0.2 0.1 0.1 0.1 0.2 0.1

15 0.1 0.1 0.1 0.1 0.1 0.2

16 0.1 0.1 0.2 0.1 0.1 0.1

17 0.1 0.1 0.1 0.1 0.1 0.1

18 0.1 0.2 0.1 0.1 0.1 0.1

19 0.1 0.1 0.1 0.1 0.1 0.1

20 0.1 0.1 0.1 0.1 0.1 0.1

Master Chart

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Table 1: Values obtained by Vernier Caliper

SL.NO RETRACTION CORD

Facial M

(mm)

Facial C

(mm)

Facial D

(mm)

Palatal M

(mm)

Palatal C

(mm)

Palatal D

(mm)

1 0.6 0.6 0.6 0.6 0.6 0.6

2 0.5 0.5 0.5 0.5 0.6 0.5

3 0.6 0.5 0.5 0.6 0.5 0.6

4 0.6 0.5 0.5 0.5 0.5 0.4

5 0.6 0.6 0.6 0.6 0.6 0.6

6 0.6 0.6 0.5 0.5 0.6 0.5

7 0.7 0.5 0.6 0.6 0.5 0.4

8 0.7 0.4 0.5 0.5 0.6 0.5

9 0.6 0.4 0.4 0.6 0.6 0.6

10 0.7 0.4 0.5 0.5 0.6 0.5

11 0.6 0.5 0.6 0.6 0.5 0.4

12 0.7 0.7 0.6 0.6 0.7 0.5

13 0.5 0.5 0.6 0.5 0.5 0.5

14 0.6 0.6 0.6 0.4 0.6 0.5

15 0.5 0.6 0.5 0.5 0.4 0.5

16 0.4 0.5 0.5 0.6 0.5 0.5

17 0.4 0.4 0.5 0.6 0.5 0.5

18 0.5 0.6 0.5 0.5 0.5 0.5

19 0.5 0.5 0.6 0.6 0.6 0.6

20 0.7 0.7 0.6 0.5 0.6 0.7


Master Chart

Page 54


SLNO EXPASYL

Facial M

(mm)

Facial C

(mm)

Facial D

(mm)

Palatal M

(mm)

Palatal C

(mm)

Palatal D

(mm)

1 0.5 0.5 0.6 0.5 0.6 0.5

2 0.4 0.5 0.4 0.4 0.6 0.4

3 0.5 0.4 0.3 0.5 0.4 0.5

4 0.4 0.4 0.4 0.4 0.4 0.4

5 0.5 0.5 0.5 0.5 0.5 0.5

6 0.6 0.6 0.4 0.4 0.5 0.4

7 0.5 0.4 0.5 0.5 0.4 0.4

8 0.7 0.4 0.3 0.4 0.6 0.5

9 0.5 0.3 0.3 0.5 0.5 0.5

10 0.6 0.4 0.4 0.4 0.5 0.4

11 0.5 0.5 0.5 0.5 0.4 0.5

12 0.6 0.6 0.5 0.5 0.6 0.4

13 0.4 0.4 0.5 0.4 0.4 0.5

14 0.5 0.5 0.5 0.4 0.5 0.4

15 0.4 0.5 0.4 0.5 0.4 0.5

16 0.4 0.4 0.4 0.5 0.4 0.4

17 0.3 0.4 0.5 0.5 0.4 0.4

18 0.5 0.5 0.4 0.4 0.5 0.4

19 0.5 0.5 0.4 0.4 0.5 0.5

20 0.6 0.6 0.5 0.5 0.6 0.6


Master Chart

Page 55


SL.NO MEROCEL STRIP

Facial M

(mm)

Facial C

(mm)

Facial D

(mm)

Palatal M

(mm)

Palatal C

(mm)

Palatal D

(mm)

1 0.3 0.3 0.4 0.3 0.4 0.4

2 0.3 0.3 0.3 0.4 0.4 0.3

3 0.4 0.3 0.4 0.4 0.4 0.3

4 0.3 0.3 0.4 0.3 0.4 0.3

5 0.2 0.3 0.3 0.3 0.3 0.4

6 0.4 0.4 0.4 0.4 0.3 0.3

7 0.4 0.4 0.3 0.3 0.5 0.3

8 0.5 0.5 0.4 0.4 0.4 0.3

9 0.5 0.5 0.4 0.3 0.4 0.4

10 0.4 0.4 0.4 0.4 0.3 0.5

11 0.4 0.4 0.3 0.3 0.3 0.3

12 0.4 0.3 0.3 0.3 0.4 0.3

13 0.3 0.3 0.3 0.3 0.3 0.3

14 0.4 0.3 0.3 0.4 0.3 0.3

15 0.4 0.3 0.3 0.5 0.3 0.4

16 0.3 0.4 0.4 0.5 0.3 0.4

17 0.4 0.3 0.3 0.3 0.4 0.4

18 0.2 0.3 0.4 0.5 0.4 0.4

19 0.3 0.3 0.3 0.2 0.3 0.3

20 0.5 0.5 0.4 0.5 0.5 0.4


Figures

Page 56

Figure 1: Mouth mirror, William’s periodontal probe, Tweezers, Cord packer (Hu-

Friedy, USA), Scissors- straight and angled, Digital Vernier caliper, Surgical gloves,

mouth mask, Cotton rolls, Cheek retractor

Figure 2: Conventional retraction cord (Ultrapak, Ultradent, USA)

Figures

Page 57

Figure 3: Expasyl retraction paste and dispensing gun

Figure 4: Merocel retraction strip

Figure 5: Tooth preparation Figure 6: Placing gingival

retraction cord using cord packer

Figures

Page 58

Figure 7: Conventional retraction cord placed

Figure 8: Expasyl placed Figure 9: Merocel retraction strip placed

Figure 10: Measurements taken using digital Figure 11: Cementation of

Vernier caliper final prosthesis.

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