Dr. DHANYA GANGADHARAN

RAJIV GANDHI UNIVERSITY OF HEALTH SCIENCES

BANGALORE, KARNATAKA

“COMPARATIVE ASSESSMENT OF FRACTURE RESISTANCE OF GLASS

FIBER POST WITH COMPOSITE CORE BUILD UP AND PREFABRICATED

RESIN COMPOSITE POST AND CORE SINGLE UNIT OF ENDODONTICALLY

TREATED MANDIBULAR PREMOLAR -AN IN VITRO STUDY”

By

Dr. DHANYA GANGADHARAN

Dissertation submitted to the

Rajiv Gandhi University of Health Sciences, Karnataka, Bangalore,

In partial fulfillment of the requirements for the degree of

MASTER OF DENTAL SURGERY

IN

CONSERVATIVE DENTISTRY AND ENDODONTICS

Under the guidance of

Dr.N.MEENA M.D.S

PROFESSOR

DEPARTMENT OF CONSERVATIVE DENTISTRY AND

ENDODONTICS, VOKKALIGARA SANGHA DENTAL COLLEGE &

HOSPITAL, BANGALORE, KARNATAKA, INDIA 2017-2020

I

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IV

ACKNOWLEDGEMENT

“Hope is wishing for a thing to come true. Faith is believing it will come true. Work is

making it come true.” --Dr. Norman Vincent Peale

This thesis is an outcome of the belief and hardwork. It would not have happened without the

support of my faculty, post graduate colleagues, and family. Dr. N Meena, Professor and my

guide at Vokkaligara Sangha Dental College has been a constant support through her

mentoring. The evolution of thoughts would not have happened without her guidance. I am

grateful for her kindness and tireless pursuit of academic excellence that has inspired me to

scale this ladder of success. Her critical evaluation and genuine care has played a role in

moulding me into the person and clinician I am today.

Dr. Usha H L, Principal & Head of the Department, always had

my best interests in mind and always supported me with all requests as part of the study.

Faculty at Department of Conservative Dentistry and Endodontics ,VSDC Professors - Dr.

Anitha Kumari, Dr. Adarsha MS, Dr. Chethana. S.Murthy , Readers - Dr. Ashwini

Santhosh, Dr. Vikram, Dr. Sudhanva, Dr. Naveen Gowda and Dr.Vijayalakshmi ,Senior

Lecturers-Dr. Shivikshith , Dr.Vishwas were always there to support and guide me.

Dr. Deepak Mehta has done extensive work in the field of post and core restoration . I thank

him for his guidance during this study.

V

VI

LIST OF ABBREVIATIONS USED

CHX CHLORHEXIDINE

EDTA ETHYLENEDIAMETETRAACETIC ACID

ETT ENDODONTICALLY TREATED TEETH

FRC FIBER REINFORCED COMPOSITE

NaOCl SODIUM HYPOCHLORITE

VII

LIST OF TABLES

LIST OF GRAPHS

Sl. No Tables Page No.

1 COMPARISON OF FRACTURE RESISTANCE 47

2

FAILURE MODE ANALYSIS 48

3

TABULATION OF THE SCORES OBTAINED

AFTER FRACTURE TESTING & FAILURE

PATTERN

50

4

TABULATION OF FAILURE PATTERN SEEN

IN TWO GROUPS

51

Sl. no GRAPH Page No.

1 COMPARISON OF FRACTURE RESISATNCE 49

2

FAILURE MODEL ANALYSIS-PERCENTAGE

WISE DISTRIBUTION

49

VIII

LIST OF FIGURES

Sl. No. Figures Page No.

1 TWENTY TEETH SAMPLES 93

2

INDIVIDUAL TOOTH SAMPLE 93

3 STORAGE 0.5% CHLORAMINE T 94

4

MARKING AT 2 MM ABOVE LEVEL

OFCEMENTOENAMEL JUNCTION 94

5 MEASURING AT 2 MM ABOVE CEMENTO

ENAMEL JUNCTION WITH VERNIER

CALIPER

95

6 DECORONATION OF THE TOOTH WITH

DIAMOND DISC

95

7 DECORONATED TOOTH SAMPLES 96

8 ROOT LENGTH STANDARIZED TO

APPROX.13MM

96

9 ARMAMENTARIUM FOR SECTIONING AND

TOOTH PREPARATION

97

10 ARMAMENTARIUM FOR BIOMECHANICAL

PREPARATION

97

11 ARMAMENTARIUM FOR OBTURATION 98

IX

12 ARMAMENTARIUM FOR POST SPACE

PREPARATION-POST DRILLS FOR

EDELWEISS POST AND CORE

98

13 ARMAMENTARIUM FOR POST SPACE AND

CEMENTATION OF POST SYSTEM

99

14 TENAX FIBER POST (GLASS FIBER POST) 99

15 EDELWEISS POST AND CORE 100

16 WORKING LENGTH DETERMINATION 100

17 IRRIGATION OF THE ROOT CANAL 101

18 BIOMECHANICAL PREPARATION UPTO F3 101

19 POST OBTURATION RADIOGRAPH 102

20 POST SPACE PREPARATION 102

21 RADIOGRAPHIC IMAGE OF POST SPACE

PREPARATION

102

22 IRRIGATION OF POST SPACE 103

23 CHECKING THE FIT OF GLASS FIBER POST 103

24 CHECKING THE FIT OF EDELWEISS POST

AND CORE

104

25

RADIOGRAPHIC IMAGE OF THE FIT OF

GLASS FIBER POST 104

26

RADIOGRAPHIC IMAGE OF THE FIT OF

EDELWEISS POST AND CORE

104

X

27

ETCHING WITH 36%PHOSPHORIC ACID

105

28

REMOVAL OF REMAINING ETCHANT AND

DRYING OF THE POST SPACE WITH PAPER

POINTS 105

29

APPLICATION OF BONDING AGENT

106

30

APLLICATION OF BONDING AGENT IN

POST SPACE 106

31

REMOVAL OF EXCESS BONDING AGENT IN

POST SPACE 107

32

CURING THE BONDING AGENT WITH

LIGHT CURING UNIT 107

33

APPLICATION OF SILANE COUPLING

AGENT ON GLASS FIBER POST 108

34

APPLICATION OF EDELWEISS VEENER

BOND ON EDELWEISS POST 108

35

INJECTING DUAL CURE CORE X FLOW

INTO THE POST SPACE FOR CEMENTATION

109

36

CEMENTATION OF EDELWEISS POST AND

CORE 109

37

TOOTH SAMPLE AFTER THE

CEMENTATION OF EDELWEISS POST AND

CORE

110

38

CEMENTATION OF GLASS FIBER POST

110

39

CORE BUILD UP AND CURING OF THE

GLASS FIBER POST 111

XI

40

RADIOGRAPHIC IMAGE OF GLASS FIBER

POST WITH DUAL CURE COMPOSITE CORE

BUILD UP

111

41

CORE BUILD UP STANDARISED TO LENGTH

OF 5.5MM AND WIDTH OF 5MM 112

42

TOTAL SAMPLES AFTER CEMENTATION OF

THE POST SYSTEM 112

43

MOUNTING OF THE SAMPLE IN ACRYLIC

BLOCK WITH SIMULATION OF

PERIODONTAL LIGAMENT

113

44

THERMOCYCLING OF THE TOOTH

SAMPLES 113

45

FRACTURE TESTING -UNIVERSAL TESTING

MACHINE 114

46

SCREEN SHOT OF FRACTURE RESISTANCE

OF EDELWEISS POST AND CORE SINGLE

UNIT

114

47

SCREEN SHOT OF FRACTURE RESISTANCE

OF GLASS FIBER POST 115

48

FAILURE PATTERN VIEWED UNDER

STEREOMICROSCOPE 115

49

TYPES OF FAILURE VIEWED UNDER

STEREOMICROSCOPE 116-118

XIII

ABSTRACT

‘COMPARATIVE ASSESSMENT OF FRACTURE RESISTANCE OF

GLASS FIBER POST WITH COMPOSITE CORE BUILD UP AND

PREFABRICATED RESIN COMPOSITE POST & CORE SINGLE UNIT

OF ENDODONTICALLY TREATED MANDIBULAR PREMOLARS-AN

IN-VITRO STUDY’

Background and Objectives: The restoration of endodontically treated teeth with

compromised crown structure requires the fabrication of a post and core to provide retention

and support for the final crown.

The purpose of this study was to assess and compare the fracture resistance and failure mode

of glass fiber post with composite core build up and prefabricated single unit resin composite

post &core.

Methods: A total of 40 human extracted mandibular premolars were used for the study. The

teeth were randomly divided into two groups and were subjected to root canal treatment and

obturated with gutta percha. After post space preparation in teeth under Group 1(n=20) glass

fiber post(TENAX® FiberTrans) was placed and a separate composite core build up was

done.In Group 2 (n=20) resin composite post and core single unit (Edelweiss post system)

was placed. All samples were subjected to thermal cycling (between 5 and 55°C, 30-second

dwell time).The fracture resistance was tested using a compressive load in an Universal

testing machine.The fracture force was measured in Newtons and failure patterns were

analyzed using stereomicroscope .

Results: The statistical test using independent t test to analyse the fracture resistance revealed

a statistical significant difference between the two group (p<0.05) .

XIV

Conclusion: The fracture resistance of prefabricated Edelweiss resin composite post and core

single unit was more than the Glass reinforced fiber post .The failure pattern observed in

Glass fiber post were non catastrophic core fracture, post debonding, post fracture and tooth

fracture while in Edelweiss post and core single unit shows non catastrophic core and tooth

fractures .There was no post debonding or post fracture in Edelweiss post and core single

unit.

Key Words: Glass fiber post ; Edelweiss post and core single unit ; fracture resistance;failure

mode

1

COMPARATIVE ASSESSMENT OF FRACTURE RESISTANCE

OF GLASS FIBER POST WITH COMPOSITE CORE BUILD UP

AND PREFABRICATED RESIN COMPOSITE POST & CORE

SINGLE UNIT OF ENDODONTICALLY TREATED

MANDIBULAR PREMOLARS-AN IN VITRO STUDY

INTRODUCTION

Endodontically treated teeth often present with compromised crown

structure.1 These teeth also present with altered esthetic, and changed physical

characteristics.1 In the past, several studies have shown that endodontically treated

teeth become brittle because of the reduction in water content and loss of cross linking

of collagen.2 Major changes are seen in tooth biomechanics on account of carious

lesions, fracture, cavity preparation and access cavity preparation . Loss of tooth

structure during access preparation affects stiffness of dentin by 5%. Additional loss

of marginal ridges attributes 14-44% reduction in tooth stiffness.2There is a reduction

of 20-63% of tooth stiffness following mesio-occluso distal cavity preparation which

results in maximum tooth fragility.2 Hence, successful outcome of pulp‑treated

permanent teeth needs proper rehabilitation procedure.1

In cases where most of the coronal portion is lost, a common

method to restore such teeth is the use of a post and core, onto which a full crown is

cemented.3 The dowel is a post of relatively rigid, restorative material placed in the

root of a root canal treated tooth which also has to retain the core.4 The post functions

primarily to aid the retention of the restoration and to protect the tooth by distributing

forces along the tooth and tooth root.5

2

Restorations of the root filled tooth by a post to retain a crown

dates back more than 200 years, when Fauchard used posts constructed from gold or

silver.6 Over the next century, the post crowns became the most popular method of

restoration of traumatized tooth. For many years the standard “Artificial Tooth

Structure” in dentistry was the post and core fabricated in cast gold. Tomes proposed

the principles of post dimensions as early as 1848 and these procedures still closely

conform to those used today.7

In the later years prefabricated posts gained importance due to

reduced time and feasibility.4 Among the prefabricated posts, metallic posts have

modulus of elasticity greater than that of dentin and causes greater stress around the

apical part of the post (apical third of the tooth) resulting in root fracture.8 Today,

various tooth‑colored posts are gaining popularity such as glass fiber post, zirconia,

and composite post.1The modulus of elasticity of tooth colored post is similar to that

of dentin . Due to favorable elasticity of tooth color post systems, stress distribution

during clinical function is uniform and spreads along the entire root canal. 9 Grandini

et al, 2005 reported that tooth color post systems with direct composite restorations

used for restoration of ETT have good clinical performance compared to metallic

dental posts systems. 10 These tooth colored post have also improved esthetics

especially when all ceramics crowns are placed .

The post endodontic treatment of teeth presents the dental

practitioner with the difficulties in selecting from a large array of materials, technique

and designs. The main reasons hindering the long term success of post retained

restorations are : Loss of retention and root fracture. Post retention can be improved

by adhesive luting.11The addition of fibers to a polymer matrix can result in a

3

significant improvement in the mechanical properties such as strength, fracture

toughness, stiffness and fatigue resistance. Adhesive composites are used to build up

the core and form a mechanical unit with the tooth.6 Also, the mechanical behaviour

and related mechanism of failure of fiber posts have been compared to those of

metallic posts. While metallic posts tend to produce an irreversible root fracture on

failure, the root fracture in case of a fiber posts is usually located more coronally and

is more easily re -treatable. In addition, the fiber posts are more easily retrievable than

metallic or ceramic posts.

At around 1966, the prefabricate posts and composite resin core came

into use.12 This system in which the prefabricated posts is cemented in root canal and

the core is built up using composite resins was devised for forming a dowel and core

which provides strength and serviceability comparable to, and often exceeding, that of

cast dowels.12

Thus the introduction of glass fiber posts and composite resin has

brought about a new concept of "Endoesthetics" into picture.3 Moreover glass fiber

post is translucent and creates a monoblock, bonding every component directly or

indirectly to the tooth and reinforces the intra-radicular tooth structure with excellent

transverse strength.13It has been observed that core structure provides stress

transmission from crown to the post structure to remaining root dentin.1 Root fracture

occurs when this stress transmission exceeds the withstanding resistance. Fracture

above the alveolar bone is considered favorable but below the alveolar bone is

unfavorable.1

4

The disadvantage of resin composite core bonded to a fiber

reinforced post is that additional clinical time is spent at the chairside in fabrication

of the core and possible cohesive failure of the bond between the composite core

material and the post surface.9,14

Thus to overcome this disadvantage of placing a separate core ,

recently Edelweiss Dentistry, Austria has introduced prefabricated tooth colored post

and composite core with high dense laser sintered composite material which has

modulus of elasticity similar to that of dentin. This post system with core is

customizable and is radiopaque with a shortened chair side time and improved

clinical characteristics.

Current literature do not provide information on the

comparison of these post systems which has core incorporated as a single unit with

that of post system with separate core and their effects on the fracture resistance of

root canal treated teeth. Thus the present study was conducted to compare the fracture

resistance and the mode of failure of endodontically treated teeth restored with glass

fiber post with composite core build up and prefabricated resin composite post and

core single unit.

5

AIMS & OBJECTIVES

AIMS

To assess and compare the fracture resistance and failure mode of glass fiber post with

a composite core build up and prefabricated single unit resin composite post &core.

OBJECTIVES

• To assess the fracture resistance of glass fiber post with a composite core build

up.

• To assess the fracture resistance of resin composite post & core single unit.

• To compare the fracture resistance of glass fiber post with composite core

build up and resin composite post & core single unit.

• To assess the failure mode as root fracture, post fracture, core fracture or any

interface debonding.

6

NULL HYPOTHESIS

There is no difference in the fracture resistance and failure mode of glass fiber post

with a composite core build up and prefabricated single unit resin composite post

&core.

7

REVIEW OF LITERATURE

1. A study was conducted to evaluate the fracture resistance of carbon, glass fiber,

and zirconia posts in which forty‑five human premolars were subjected to root

canal treatment and obturated with gutta‑percha and were decoronated and

mounted in acrylic block. The teeth were then equally divided into three groups:

(a) carbon, (b) glass fiber, and (c) zirconia post group. Post space was prepared

and particular post was cemented in post space and core buildup with composite

was done . A compressive load was applied using universal testing machine and

fracture force was measured in MPa. The data was tabulated, and statistical

evaluation using one‑way analysis of variance and Bonferroni post hoc test was

done. The Zirconia endodontic post had good fracture resistance (489.2 MPa)

when compared with carbon (258.4 MPa) and glass fiber‑reinforced post (348.7

MPa) and was statistically significant (P>0.01) .They concluded that zirconia post

had good fracture resistance compared to glass fiber and carbon posts.1

2. An invited review revealed that there was a high risk involved in losing the

endodontically treated posterior teeth due to fracture and thus to reinforce the cusp

of pulpless teeth the authors recommended the use of crown that encompasses the

cusps to withstand the occlusal forces of everyday mastication.This was after their

clinical observation over a period of 25 years which has led them to believe that

root canal treated teeth irrespective of the amount of tooth structure lost either by

caries or access cavity preparation ,mostly fracture if not protected by full cast

crowns.2

8

3. A study was conducted to compare the fracture resistance and the mode of failure

of endodontically treated teeth restored with different post-core systems in which

40 maxillary incisors were divided into four groups of 10 teeth each. For three

experimental groups post space preparation was done and teeth were restored with

cast post-core (Group B), stainless steel post with composite core (Group C) and

glass fiber post with composite core using adhesive resin cement (Group D).

Control group (A) samples were selected with intact coronal structure, all the

samples were prepared for ideal abutment preparation and were subjected to a

load of 0.5 mm/min at 130 degree until fracture occurred using the Universal

testing machine. The statistical analysis of fracture resistance between different

groups was carried out with t-test and the mode of failure was carried out by

Kruskal-Wallis test and Chi-Square test.They concluded that endodontically

treated teeth without post core system showed the least fracture resistance

demonstrating the need to reinforce the tooth. Stainless steel post with composite

core showed the highest fracture resistance among all the experimental groups

while the teeth restored with the Glass fiber post showed the most favorable

fractures making them more amenable to the re-treatment.3

4. A study was done to evaluate the fracture resistance strength of different post

systems in endodontically treated teeth for which extracted 60 single-rooted first

premolars were selected and conventional step-back technique was used to

prepare a canal for all the teeth followed by obturation and post space was created

using a Peeso reamer. All teeth were randomly divided into three groups of 20

9

samples in each group: In Group I, teeth was inserted with prefabricated carbon

posts; in Group II, teeth were inserted with prefabricated zirconia posts; and

Group III, teeth were inserted with prefabricated EverStick posts. Core buildup

was performed using light-cured composite resin and compressive load required to

fracture the tooth was measured using a Universal testing machine. The

compressive strength of zirconia posts was highest with a mean of 796.10 ± 20.78

followed by carbon posts (628.22 ± 18.11) and lower compressive strength was

exhibited by EverStick posts (534.13 ± 19.9) that was statistically highly

significant (P < 0.005) among the different posts used. They concluded that

Zirconia posts had maximum fracture resistance than the carbon posts and

EverStick posts.4

5. A study was done in which forty-eight human premolars the crowns were cut from

3 mm above the CEJ and mesiodistally cavities were prepared, measuring 3 mm

buccolingually dimension. Upon completion of root canal treatment, the following

procedures were followed: in the first group, fiber posts #1 (Tokuyama Dental

Corp.,Tokyo, Japan) and the crowns were restored with resin composite; Estelite

Sigma Quick (Tokuyama Dental Corp.,Tokyo, Japan). The second group, the

roots and crowns were restored using a combination of self-etch adhesive; Bond

Force (Tokuyama Dental Corp.,Tokyo, Japan) as the manufacturers’ instructions,

and light-cure resin composite; Estelite Sigma Quick (Tokuyama) that was packed

incrementally with plugger and condenser from apical to coronal of preparations.

For the group 3, self-cured composite; Master Dent (USA), and the corresponding

adhesive in the package were used to reconstruct the roots and crowns similar to

group 2. With respect to the group 4, the self-etch resin cement; Panavia F 2.0

10

(Kuraray, Dental Inc., Okayama, Japan) was used for cementation of fiber posts

and the core building was performed employing resin composite; Clearfil AP-X

(Kuraray, Dental Inc., Okayama, Japan). Regarding the fifth group (control

group), the teeth remained untouched. After 24 hours storage and 1000

thermocycles, samples were loaded at a cross head speed of 1 mm per minute. A

significant difference was observed in fracture resistance among groups 4 and 5

compared to other groups thus concluding that root reconstruction with fiber post

and Panavia resin cement, and crown building using light-cured resin composite

resulted in increased fracture resistance equal to that of intact teeth.8

6. A study was conducted in which tooth colored posts were reviewed (functionally

graded composite, zirconia and fiber reinforced composite) to aid the dentist in

restoration of endodontically treated teeth. They mentioned the advantages of the

tooth colored posts such as, its favorable esthetics, ease of use, their modulus of

elasticity values that are similar to that of dentin and that this can reduce the risk

of fractures as well as stress concentration at the apex of root. They were of the

view that restoration with tooth colored post can increase the survival of

endodontically treated teeth as compared to metallic post. They found that the

most complication of the tooth colored post system was the debonding

failures.But these type of failures allowed for the retreatment of the debonded

post. They suggested that multiple factors must be considered in choosing a final

restoration which included the amount of remaining sound tooth structure,occlusal

functions ,opposing dentition and position of the tooth in the arch as well as length

width and curvature of the roots and that practitioners must always use their best

11

professional judgement ,taking into account the need of each individual patient

when choosing a restorative plan.9

7. A study was done to present a preliminary clinical report on the use of fiber posts

and direct resin composites for restoring root-treated teeth.Thirty-eight anterior

and 62 posterior endodontically treated teeth were selected from 3 private

prosthodontic offices. The protocol used included endodontic treatment, with

translucent fiber posts (DT post) bonded to the post-space using a ‘1-bottle’

adhesive (One-Step, Bisco) and a dual-cure resin cement (DuoLink, Bisco). Direct

resin restorations were performed using a micro-hybrid resin composite (Gradia

Direct, GC) and a layering technique. Both opaque dentin,enamel and translucent

enamel shades were used.The patients were recalled after 6, 12, 24, and 30

months, and the restorations were assessed according to predetermined clinical

and radiographic criteria.They concluded that restoration of endodontically treated

teeth with fiber posts and direct resin composites is a treatment option, that in the

short term conserves remaining tooth structure and results in good patient

compliance.10

8. A survey was done to characterize and analyze reported failures of post-retained

restorations to identify factors critical to failure .This was carried out by mailing

private practitioners in Denmark with a request to complete the questionnaire

whenever a patient presented with a failed post-retained restoration. Information

was gathered on factors related to the patient, the tooth, the restorative materials,

and the techniques. Two-hundred and sixty questionnaires were collected from

171 practitioners over a 3-year period. Functioning time of the restoration until

12

failure varied between 3 months and 38 years. Mean survival time until failure

was 11 years. Of the failed restorations, 61% had functioned for 10 years or less.

Tapered posts implied an increased risk of tooth fracture compared to loosening or

fracture of the post, and the relative risk of tooth fracture thus concluding that

tapered posts were associated with a higher risk of tooth fracture than were

parallel-sided posts.11

9. A study was done to evaluate the mode of failure of glass fiber post for which 20

extracted single-rooted teeth were endodontically treated and restored with glass

fiber posts. They were then loaded using Universal testing Machine until failure

occurred. Then, the mode of failure of each sample was determined and

categorized as (a) root fracture, (b) core fracture, (c) post fracture, and (d) post

debonding ,11 samples showed post debonding as a mode of failure and in 05

samples there was core fracture, post fracture were seen in the remaining 04

samples. They concluded that the mode of failure for prefabricated glass fiber post

is predominantly post debonding followed by core fracture and post fracture.12

10. A study was done to evaluate the influence of 3 different post-resin matrix

systems cemented with dual-cure resin cement in simulated root canals made of

PMMA acrylic sheet. Three types of fiber posts with different resin matrixes were

divided into 3 groups: group 1 cross-linked FRC Postec Plus post, group 2 cross-

linked Rely X post , and group 3 Interpenetrated IPN Everstick post . All posts

were cemented using Multilink Automix dual-cure cement. Posts were cemented

into acrylic blocks in order to purely test the strength of cement-post interface.

After one week storage at 37° C, two sections of 1 mm thickness from middle-

13

third were subjected to micro-push-out test at crosshead speed 0.5 mm/min. They

concluded that prefabricated cross-linked posts with epoxy-based matrix

demonstrated higher bond strength than prefabricated cross-linked posts with Bis-

GMA-based matrix and posts with semi-IPN matrix when luted with

dimethacrylate-based dual-cured resin cement.14

11. A study was done to evaluate the fracture resistance of two types of post materials

and two types of core material.Forty extracted human mandibular premolar were

selected and after root canal preparation and obturation with gutta percha the roots

were divided into two groups according to the type of post material, group F

restored with fiber post and group T restored with titanium post then each group

was subdivided into two subgroup according to the type of core materials which

include composite and amalgam restorative materials. Then all the teeth were

subjected to compressive load at 130 degree angle from the horizontal plan at a

5mm/min crosshead speed until fracture. The results showed that there was

significant difference between groups in term of fracture loads (P= 0.0156).The

fracture loads of teeth restored with titanium post and composite core had highest

mean fracture load (812N), whereas teeth restored with fiber post and amalgam

core demonstrated the lowest mean fracture load (643.1N). They concluded that

the teeth restored with metal titanium post was more fracture resistant than those

restored with fiber posts. But the combination of a fiber post and composite core

had a favorable mode of fracture that was considered repairable, while titanium

post restoration was considered unfavorable .15

14

12. A study was done by to evaluate the influence of glass-fiber post placement on

the fracture resistance of endodontically treated premolars with varying degrees of

substance loss. Sixty-four extracted and endodontically treated mandibular

premolars were divided into four test groups (n=16) depending on the number of

residual coronal dentin walls that ranged from 3 to zero. Teeth in subgroups were

either adhesively restored with composite resin without a post (-) or with an

adhesively luted glassfiber post (+). After receiving a 0.8-mm shoulder

preparation, providing a ferrule of 0.5 mm, teeth were restored with complete

metal crowns, which were cemented with glass ionomer cement. All specimens

were subjected to dynamic loading in a masticatory simulator for 1.2 million

loading cycles with a nominal load of 49 N at 1.2 Hz combined with thermal

cycling (between 5 and 55°C, 30-second dwell time). Then specimens were quasi-

statically loaded at 30 degrees in a universal testing machine until fracture. Data

were analyzed with 2-way ANOVA ,followed by multiple comparisons using

Tukey HSD test (α=.05).The results showed that no specimen failed during

masticatory simulation. Mean final fracture resistance ranged from 335.6 N to

1064.9 N. Two-way ANOVA revealed that both the number of residual coronal

walls and post placement had a significant influence on the fracture

resistance(P<.001). However, pair-wise comparisons of groups showed that in

groups with 2 or 3 cavity walls, the post effect was not statistically significant

(P=.378 and P=.175, respectively) thus concluding that the fracture resistance of

endodontically treated premolars was dependent on the number of residual coronal

dentin walls. Placement of a glass-fiber post had a significant influence on the

fracture resistance when fewer than two cavity walls remained but no significant

influence when 2 or 3 walls were present.16

15

13. A study was done to determine and compare the fracture resistance of

endodontically treated maxillary central incisors restored with different posts and

core. Forty-eight upper central incisors were randomly divided into four groups:

cast post and core (group 1), fiber-reinforced composite (FRC) post and composite

core (group 2), composite post and core (group 3), and controls (group 4). Mesio-

distal and bucco-lingual dimensions at 7 and 14 mm from the apex were compared

to ensure standardization among the groups. Twelve teeth were prepared for

crown restoration (group 4). Teeth in other groups were endodontically treated,

decoronated at 14 mm from the apex, and prepared for posts and cores. Resin-

based materials were used for cementation in groups 1 and 2. In group 3,

composite was used directly to fill the post space and for core build-up. All

samples were restored by standard metal crowns using glass ionomer cement,

mounted at 135° vertical angle, subjected to thermomechanical aging, and then

fractured using a universal testing machine. The results showed that fracture

resistance of the groups was as follows: Control (group 4) > cast post and core

(group 1) > fiber post and composite core (group 2) > composite post and core

(group 3). All samples in groups 2 and 3 fractured in restorable patterns, whereas

most (58%) in group 1 were non-restorable thus concluding that FRC posts

showed acceptable fracture resistance with favorable fracture patterns for

reconstruction of upper central incisors.17

14. A study was conducted to compare the effect of 3 fiber-reinforced composite post

systems on the fracture resistance and mode of failure of endodontically treated

teeth. Ninety maxillary central incisors were divided into 8 experimental groups

and 1 stainless steel (ParaPost) control group of 10 specimens each. Eighty teeth

16

were assigned to two main experimental groups called “narrow” and “flared”

canals. For the narrow canal group, post spaces were prepared with the

corresponding reamer to restore the teeth with FibreKor, Luscent anchors, and

Ribbond posts of 1.5 mm, 1.6 mm, and 2.0 mm in diameter, respectively. For the

flared canals group thin-walled canals were simulated. Teeth for the flared canals

were restored with the same posts but were cemented into tapered 2 mm wide

canals created with a tapered diamond bur. Prefabricated posts (FibreKor and

Luscent anchors) for narrow and flared canals were cemented with an

autopolymerized resin cement and a flowable composite, respectively, whereas

customized Ribbond posts were luted with a light-polymerized flowable

composite for both canal types. An additional set of 20 Ribbond posts with

coronal portions of variable size and shape referred to as “Ribbond non

standardized” were also prepared and evaluated. Specimens were loaded to failure

(kg) with a universal testing machine at a crosshead speed of 0.05 cm/min until

failure occurred. Data were analyzed with analysis of variance and Student t tests .

The results of statistical analysis revealed no significant difference between flared

and narrow canals in mean load to failure between the post systems except for the

Ribbond posts . No root fractures occurred in any of the experimental groups thus

concluding that the load to failure of the stainless steel posts were significantly

stronger than all the composite posts studied. However, the mode of failure or

deflection of the fiber-reinforced composite posts was protective to the remaining

tooth structure.18

15. A study was done to compare the root fracture resistance of extracted teeth

treated with different fibers reinforced with composite posts and treated teeth with

17

conventional post and core systems. In 50 mandibular first premolars the coronal

portion of each tooth was amputated, and five post and core systems (cast,

polyethylene woven, glass, carbon, and quartz fiber posts) were compared.

Acrylic resin blocks were used for mounting, using a layer of elastomeric

impression material covering the roots. The load was applied axially and

measured with a universal testing machine. The results concluded that

significantly, cast posts and cores had a higher failure threshold including teeth

fracture; whereas, fiber posts failure was due to core fracture, with or without

fractures in coronal portion of posts. Difference in FRC posts did not provide any

significant difference in the load failure and the mode of fracture.19

16. A study was done to determine the mode of failure and compare the fracture

resistance of endodontically treated teeth restored with GC EverStick post and

Easy post .30 single rooted first mandibular premolars were endodontically

treated. All the samples were randomly divided into 3 groups (n=10) according to

the post system. (GC EverStick post – Group I, Easy post - Group II –, Negative

control - Group III). In all the samples, mesio-occluso-distal (mod) cavities were

prepared and restored with composite restorative material (filtek z250xt). Fracture

resistance was measured in a universal testing machine (Mecmesin, England) until

fracture .The results showed that Group I showed highest mean fracture resistance

(819.91N), followed by Group II (425.31N) and control group (204.82N). All the

samples restored with GC ever Stick post showed repairable fracture whereas 60%

samples restored with easy post showed repairable fracture .They concluded that

EverStick post could be a simple and efficient way to rehabilitate endodontically

treated teeth.20

18

17. A study was done to evaluate the bond strength of fiber posts luted with a one-step

self-etching adhesive after phosphoric acid conditioning of the root dentin. Thirty-

six single-rooted teeth were endodontically treated. Teeth were sectioned

perpendicularly to the cementoenamel junction, and a 10-mm post space was

prepare with a calibrated bur. Specimens were then divided into three groups

according to the adhesive protocol with Group A-total etch three steps ,Group B-

self etch one step and Group C- 32% phosphoric acid conditioning and self-etch

one step. Fiber posts were luted with self-curing resin based cement. Teeth were

cut in 1-mm slices and pushed until failure with an Instron machine .The results

were statistically analysed with ANOVA and Bonfferoni test (P < .05).Two

additional specimens from each group were examined under the scanning electron

machine .The 32 % phosphoric acid significantly influenced the push out bond

strength of fiber posts luted with self-etch adhesives (P < .05). SEM analysis

showed a continuous hybrid layer with resin tags and lateral branches in group A

and C while group B showed smear layer dissolution with poor infiltration of

tubules.21

18. A study was done by to compare the fracture resistance of endodontically treated

teeth restored with glass fiber post and composite resin cores, customized zirconia

posts, and cast metal post and cores.Forty human extracted mandibular first

premolars were used for the study. The teeth were randomly divided into four

groups. Group A represented a control group that did not receive any posts and

was filled with core material only; Group B comprised cast metal posts and cores;

Group C comprised custom milled zirconia posts and cores; and Group D

19

comprised glass fiber posts. All groups were prepared to receive all ceramic

crowns. All samples were subjected to compressive testing with an Instron

machine (Universal Testing Machine) and fracture loads and failure patterns were

analyzed. The findings indicated a statistically significant difference between the

failure loads in the groups studied. The mean load required to fracture the zirconia

custom posts was higher (765.1 ± 48.5 N) than the fiber posts and the cast posts

and cores (P < 0.001). The fiber posts resisted a mean load of561.4± 37.2 N which

was higher than the cast posts and cores. The control group revealed the lowest

value of fracture resistance.They concluded that customized zirconia posts and

cores resisted a higher mean load (765.1+ 48.5) when compared with other post

and core systems. Failure patterns within this group revealed catastrophic failure,

but the failure loads were much higher than the average occlusal load.22

19. A study was done to investigate the in-vitro fracture resistance of devitalized

teeth and mode of failure of teeth restored with posts of different materials and

different lengths .Sixty freshly extracted human mandibular premolars were

endodontically treated and then restored with 1 of 2 prefabricated posts: Stainless-

steel (SS) and glass-fiber (fiber posts [FP]) with intraradicular lengths of 4, 5 or

10 mm (n = 10). Following core restoration, a static compressive load was applied

perpendicular to the long-axis of the teeth. Initial failure of each specimen was

recorded in Newton. The mode of failure was also determined radiographically.

The data were analyzed using two-way ANOVA and Tukey’s post-hoc analysis

with Bonferroni adjustment.The results indicated significant differences (P <

0.001) among the groups. Among the SS posts, SS/7 (246 N) exhibited the highest

failure load and SS/4 (122 N) the lowest. FP/10 (140.5 N) exhibited the highest

20

failure load among the FP and FP/4 (68.5 N) the lowest. SS posts showed post

pull out, followed by core fracture while FP showed core debonding, followed by

core fracture as the primary mode of failure.They concluded that fracture

resistance of the teeth proportionately increased with increase in the length of FP

while it decreased with that of metal post. SS posts showed greater fracture

resistance than FP when 90° load was applied.23

20. A study was done to determine the fracture strength of endodontically treated

teeth restored with glass fiber reinforced or cast gold post and cores cemented

with 3 cements.Forty-two single-rooted premolars with standardized weakened

roots were endodontically treated and allocated to 6 experimental groups (n=7)

defined by the 2 factors investigated: post system and cement.Three groups were

restored with glass fiber posts and resin-modified glass ionomer cement, dual-

polymerizing resin cement, or chemically active autopolymerizing resin cement.

The other 3 groups were restored with cast gold post and cores and the same 3

cements. The cores of the glass fiber post groups were fabricated with composite

resin core material. Metal crowns were cemented on the cores in the 6 groups. The

entire system was subjected to continuous compression in a universal testing

machine, and fracture limit and location (cervical third, middle third, or apical

third) were noted. Two-way ANOVA and the Scheffé test were used to analyze

the data and compare the groups (α=.05).The results showed that two-way

ANOVA showed significant differences in the post type (P<.001) and the cements

(P<.001). The interaction between them (P<.001) was statistically significant in

the fracture resistance of the endodontically treated teeth. The greatest interaction

between post and cement was the glass fiber post with resin-modified glass

21

ionomer cement, followed by the cast gold post and core with resin-modified glass

ionomer cement. They concluded that glass fiber reinforced post and resin-

modified glass ionomer cement increased the fracture resistance of endodontically

treated teeth.24

21. A study was done to evaluate the combined effect of ferrule height and post length

on fracture resistance and failure mode of endodontically treated teeth restored

with glass fibre posts, composite resin cores and crowns .Ninety human maxillary

central incisors were endodontically treated and divided into three groups (n =

30) according to the ferrule heights: 4, 2 and 0 mm, respectively. Post spaces in

each group were prepared at 2/3, 1/2 and 1/3 of the root length (n = 10). The

specimens received fibre posts, composite resin core build up and cast metal

crowns. After thermocycling, compressive static load was applied at an angle of

135° to the crowns. The statistical analysis showed that there is a significant

differences in the failure load in the ferrule height groups, no significant

differences in post length groups and no significant interaction between ferrule

heights and post lengths. More restorable failure modes were observed.25

22. A study was done to evaluate the influence of different post lengths upon root

fracture resistance.Seventy Eight maxillary central teeth with similar dimensions

were mounted in acrylic blocks with artificial silicone periodontal ligaments.

Combinations of post lengths of 6 mm (shorter than 1/1 clinical crown length), 9

mm (1/1 clinical crown length), and 12 mm (longer than 1/1 clinical crown length)

made up 6 different groups consisting of 13 teeth each. The glass fiber posts

(Snowpost) were cemented with Super-Bond C&B and Panavia F luting cement.

22

Composite-resin cores were made with Clearfil PhotoCore. The specimens were

tested in a universal test machine. The testing machine applied controlled loads to

the core, 2 mm from its incisal edge, on the palatal side at an angle 135 degrees to

the long axis of the root. The testing machine was set at a crosshead speed of 5mm

per minute. All samples were loaded until failure. No statistically significant

difference between cements (P>.05). Posts shorter than clinical crown length,

demonstrated root fracture under significantly lower loading forces (P<.05) thus

concluding that usage of posts shorter than clinical crowns should be avoided to

eliminate clinical failure.26

23. A study was done by to evaluate the effect of thermocycling on push out bond

strength of glass fiber post to radicular dentin when cemented with a self-adhesive

resin cements. Forty single-rooted human teeth were treated, post space prepared

to received glass fiber post (luxa post) and was cemented with self adhesive dual

cure resin cements (PermaCem 2.0).The teeth were divided randomly in to 4

groups(n=10). Group1: 10 roots (without thermocycle test),Group2: 10 roots

thermocycle for 500 cycles. Group 3: 10 roots thermocycled for 1000, Group 4:

10 root thermo cycled for 2000cycles between (5 -55) ̊ Cusing thermocycler

machine (USA), root were coded and placed in 100% humidity at 37 ̊ C for 7

days. A horizontal sections of 2-mm thickness were cut from each root, then

specimens were subjected to push out test using universal testing machine.The

results showed that no significant difference between thermocycled and non –

cycled samples, the failure mode were adhesive, cohesive and mixed.They

concluded that Glass-fiber post (luxa post)and self adhesive resin cement

23

(PermaCem 2.0) offer acceptable level of retention and not susceptible to produce

significant reduction in push out bond strength.27

24. A study was done to compare the fracture resistance of teeth restored with fiber-

reinforced composite (FRC) posts and experimental dentin posts milled from

human root dentin. Thirty maxillary central incisors were divided into three

groups of ten each. Twenty teeth were restored with FRC posts and solid dentin

posts and numbered as Groups 2 and 3 respectively while Group 1 acted as the

control, without any post. The teeth were loaded at 135° angle to their long axes

after core build-up and the failure loads were recorded.Among test groups, the

control group showed the highest fracture resistance, followed by the dentin post

group and lastly the FRC post group.They concluded that teeth restored with

dentin posts exhibited better fracture resistance than those restored with FRC

posts.28

25. A study was done to evaluate and compare the fracture resistance and mode of

failure of simulated traumatized permanent central incisors restored with three

different post systems including biologic dentin posts. A total of 40 recently

extracted human maxillary central incisors with similar dimensions were

decoronated 2 mm above the cemento-enamel junction and endodontically treated.

Ten specimens were randomly selected as the Group I — Control group (core

built teeth without intraradicular posts).The remaining 30 teeth were equally

divided and restored with zirconia (Group II, n = 10), fiber re-inforced composite

(FRC) (Group III, n = 10) and biologic dentin posts (Group IV, n = 10) using resin

bonded cement and their cores built-up. These samples were embedded in acrylic

24

resin and then secured in a Universal Testing Machine and subjected to fracture

resistance testing. The location of failure in the specimens was evaluated using a

stereomicroscope. The results revealed that the control group and zirconia post

group (522 ± 110 N) demonstrated the least fracture resistance, while dentin post

group (721 ± 127 N) the highest. There was no statistically significant difference

between fiber post and dentin post groups. Fractures that were repairable were

observed in fiber post and dentin post groups, whereas mostly unrestorable,

catastrophic fractures were observed in the zirconia post group.They concluded

that teeth restored with the biologic dentin post system demonstrated the highest

fracture resistance and repairable fractures that was closely followed by FRC post

system. The least fracture resistance and most catastrophic fractures were

demonstrated with the zirconia post system.29

26. A study was done to evaluate the influence of glass fiber post length on the fracture

resistance of endodontically treated teeth. Forty intact human maxillary canines

were selected and divided into 4 groups, the control group consisted of teeth

restored with a custom gold cast post and core, with a length of two-thirds of the

root. Other groups received prefabricated glass fiber posts in different lengths:

group 1/3, removal of one-third of the sealing material (5 mm); group 1/2, removal

of one-half of the sealing material (7.5 mm); and group 2/3, removal of two-thirds

of the sealing material (10 mm). All the posts were cemented with resin cement,

and the specimens with glass fiber posts received a composite resin core. All the

specimens were restored with a metal crown and submitted to a compressive load

until failure occurred. The results were evaluated by 1-way ANOVA, and the all

pairwise multiple comparison procedures (Tukey honestly significantly difference

25

test).The ANOVA showed significant differences among the groups (P<.002). The

Tukey test showed that the control group presented significantly higher resistance

to static load than the other groups (control group, 634.94 N; group 1/3, 200.01 N;

group 1/2, 212.17 N; and group 2/3, 236.08 N). Although teeth restored with a cast

post and core supported a higher compressive load, all of them fractured in a

catastrophic manner. For teeth restored with glass fiber posts, the failure occurred

at the junction between the composite resin core and the root thus concluding that

the length of glass fiber posts did not influence fracture load, but cast post and cores

that extended two-thirds of the root length had significantly greater fracture

resistance than glass fiber posts.30

27. A study was done to compare the efficacy of resin composite restorations, retained

with either polyethylene or zirconia-rich glass fiber posts for which sixty-two

single rooted maxillary and mandibularcentral incisor teeth in forty-four patients

(15 males and 29 females; age range 15-32 years) were restored either with an

ultrahigh molecular weight polyethylene (UHMWP) fiber post (Bondable

Reinforcement Ribbon, DENSE, Ribbond, Seattle, WA, United States) or a

zircon-rich glass fiber post (Snowpost, Lot H 040; Carbotech, Ganges, France).

Then, direct resin composite restoration (Clearfil AP-X, Kuraray) was performed

for both post systems. Patients were recalled for routine inspections at 6 months ,

1, 2 and 3 years.The restorations were assessed during each recall evaluation

according to predetermined clinical and radiographic criteria (periapical lesion;

marginal leakage and integrity; color stability; surface stain and loss of retention

of the post or the composite buildup material). The follow-up data showed no

significant difference in these criteria between polyethylene fibre posts and

26

zirconia-rich glass fibre posts thus concluding that the efficacy of resin composite

restorations, retained with either polyethylene or zirconia-rich glass fiber posts

were similar, suggesting that both types of fiber post can be used successfully to

help retain resin composite restorations.31

28. A study was done to evaluate the incidence of root fracture and mode of failure

of endodontically treated teeth restored with two different post and core system

for which Forty maxillary central incisors were randomly divided into two

groups. (n=20). All teeth received endodontic treatment. First group was restored

with custom cast post and core system. Second group was restored with glass fiber

post and composite core system. In both the groups posts were cemented with

adhesive resin cement. Compressive load was applied at an angle of 130 to the

long axis of teeth at a cross head speed of 1 mm/min until fracture occurred. The

results showed that mean value for fracture resistance was (331.4025) N in Group

-I Custom cast Ni-Cr post and core and (237.0625) N in Group -II Glass fiber

reinforced post and composite core system. A significant difference in fracture

resistance of two group was seen.They concluded that the incidence of root

fracture was significantly higher in custom cast Ni-Cr post and core system than

glass fiber post and composite core system. A more favourable mode of failure

was observed in teeth restored with Group II glass fiber post system.32

29. A study was done to compare the effect of different irrigants on smear layer

removal after post space preparation.Seventy Five extracted anterior human teeth

were selected. The canals were instrumented by rotary system and then were

27

filled. After preparing the post space, teeth were divided into 5 groups according

to irrigants: 17% EDTA; 17% EDTA+2% CHX; 5.25% NaOCl; 17%

EDTA+5.25% NaOCl; and saline. The canals were irrigated with 5 cc of each

irrigants for 1 min. Specimens were examined with scanning electron microscopy

(SEM).The results revealed that subsequent use of 17% EDTA+5.25% NaOCl

was more effective than the other groups in smear layer removal. No statistical

difference was found among different levels of root canal within each group thus

concluding that 17% EDTA+5.25% NaOCl could be an effective irrigant for

smear layer removal after post space preparation.33

30. A study was done to evaluate the root fracture strength of human single-rooted

premolars restored with customized fiberglass post-core systems after fatigue

simulation. Forty human premolars had their crowns cut and the root length was

standardized to 13 mm. The teeth were endodontically treated and embedded in

acrylic resin. The specimens were distributed into four groups (n=10) according to

the restorative material used: prefabricated fiber post (PFP),PFP+accessory fiber

posts (PFPa), PFP+unidirectional fiberglass (PFPf), and unidirectional fiberglass

customized post (CP). All posts were luted using resin cement and the cores were

built up with a resin composite. The samples were stored for 24 hours at 37°C and

100% relative humidity and then submitted to mechanical cycling. The specimens

were then compressive-loaded in a universal testing machine at a crosshead speed

of 0.5 mm/minute until fracture. In the results suggest that a statistical differences

was not observed among the groups. All groups showed favourable restorable

28

failures. Fiberglass customized post did not show improved fracture resistance or

differences in failure patterns when compared to prefabricated glass fiber posts.34

31. A study was done to compare the fracture resistance and primary mode of failure

of three different pre- fabricated posts like stainless steel, carbon fiber and

ceramic posts in endodontically treated crowned permanent maxillary central

incisors. Root canal treatment was performed on all 30 maxillary central incisors.

Post space was prepared and samples were divided into three groups of 10 each.

The teeth were inserted with pre-fabricated stainless steel, carbon fiber and

ceramic post and cemented using adhesive resins, core fabricated and crowns

placed. Mode of failure was carried out by immersing the teeth in black ink for 12

h and then sectioning them mesio-distally. Fracture above the embedded resin was

considered favorable and fracture below the resin level was considered

unfavorable. There was a statistically significant difference showing that the

stainless steel post had a better fracture resistance when compared with the other

two posts and the carbon fiber showed a statistically more favorable fracture when

compared with the other two posts. Within the limitations of this study, he

concluded that the pre-fabricated stainless steel post exhibited a significantly

higher fracture resistance to failure when compared with the carbon fiber post and

the ceramic post. The mode of failure of the carbon fiber post was more favorable

to the remaining tooth structure when compared with the pre-fabricated stainless

steel post and the ceramic post.35

32. A study was done to evaluate in vitro the fracture resistance of quartz fiber posts

for three different dowel lengths. Thirty single-rooted human premolars with

29

similar root length and diameter were endodontically treated and randomly

divided into three experimental groups (n = 10) according to the post space depth

created: (1) 5 mm; (2) 7 mm; (3) 9 mm. Quartz fiber posts (Endo Light post) were

cemented using a dual cured resin cement with its adhesive system (Prime &

Bond NT + Fluorocore 2). After 24 hours, specimens were embedded in acrylic

resin and loaded under continuous compressive force at the extruding coronal part

of the post (45-degree angle) to the long tooth axis (crosshead speed: 0.75

mm/minute). Forces at fracture (Newtons) were recorded.The results showed that

there was no statistically significant differences were found among the groups.36

33. A study was done to compare the fracture resistance and failure patterns of 90

mandibular molars restored using resin composites with or without fiber posts,

with respect to the number of residual cavity walls. Five restoration types were

performed corresponding to different wall defects (groups 1-5). Groups were

divided in two subgroups corresponding to the use or absence of fiber posts. Teeth

were loaded and resistance of specimens was measured as the axial compressive

load to cause fracture and macroscopic fracture patterns were observed. One way

ANOVA revealed a significant difference in fracture resistance (p < 0.001). Tukey

post hoc test also revealed significant differences between groups as samples

restored with fiber posts exhibited mostly restorable fractures. They concluded

that the resistance of endodontically treated mandibular molars restored with

composite resins is mainly affected by the number of residual walls. Using fiber-

reinforced posts optimized fracture patterns.37

30

34. A study was done to determine and compare the fracture resistance of

endodontically treated teeth restored with two different glass fiber posts for which

thirty extracted intact human premolar teeth were selected for the study. All the

teeth were decoronated maintaining root length of 15mm from apex. Root canals

were enlarged using protaper rotary file. Obturated with gutta-percha using AH

26sealer, specimens were divided into 3 groups (n-10). In group1 Ever Stick posts

was luted into the root canals using dual cure resin cement variolink II, in group2

Hi-rem posts were luted into the root canals, group 3 did not receive any posts. In

group 1 and group 2 gutta-percha was removed, and post space was prepared

using peso reamers. Fracture loading was accomplished using an universal testing

machine at a cross head speed of 1mm/min in compression mode.The results

showed that Group3 showed highest mean fracture resistance value (795 N),

followed by group 1 (Ever Stick post) with mean value (715.40 N) and group2

(Hi-rem) with mean value (476N).They concluded that teeth restored with Ever

Stick post has better fracture resistance value than Hi-rem posts.38

35. A study was done to assess the fracture resistance of three composite resin core

build-up materials on three prefabricated non-metallic posts, cemented in

extracted endodontically treated teeth. Forty-five freshly extracted maxillary

central incisors of approximately of the same size and shape were selected for the

study. They were divided randomly into 3 groups of 15 each, depending on the

types of non-metallic posts used. Each group was further divided into 3 groups (A,

B and C) of 5 samples each depending on three core build-up material used. The

results suggest Luxacore showed the highest fracture resistance among the three

core build-up materials with all the three posts systems. Ti-core had intermediate

31

values of fracture resistance and Lumiglass had the least values of fracture

resistance.39

36. A study was done to evaluate the fracture resistance of endodontically treated

teeth restored with fiber reinforced composite posts, using three resin composite

core build-up materials, (Clearfil Photo Core (CPC), MultiCore Flow (MCF), and

LuxaCore Z-Dual (LCZ)), and a nanohybrid composite, (Tetric N-Ceram

(TNC).Forty endodontically treated lower first premolars were restored with

quartz fiber posts (D.T. Light-Post) cemented with resin cement (Panavia F2.0).

Samples were randomly divided into four groups (n=10). Each group was built-up

with one of the four core materials following its manufacturers’ instructions. The

teeth were embedded in acrylic resin blocks. Nickel-Chromium crowns were fixed

on the specimens with resin cement. The fracture resistance was determined using

a universal testing machine with a crosshead speed of 1 mm/min at 135⁰ to the

tooth axis until failure occurred. All core materials used in the study were

subjected to test for the flexural modulus according to ISO 4049:2009. The results

suggested that the fracture resistance was higher in the groups with CPC and

MCF, which presented no statistically significant difference (p>0.05), but was

significantly higher than in those with LCZ and TNC (p<0.05). In terms of the

flexural modulus, the ranking from the highest values of the materials was aligned

with the same tendency of fracture loads.They concluded that among the cores

used in this study, the composite core with high filler content tended to enhance

fracture thresholds of teeth restored with fiber posts more than others.40

32

37. A study was done to analyze whether self-etch and self-adhesive systems are

comparable to the total-etch system for fiber post cementation.Twenty seven

mandibular premolar teeth randomly divided into three groups. fiber post

cementation was done using three different adhesive systems. specimens were

prepared with a thickness of 5 mm, which was measured from the cervical to

medial areas of the root, and stored for 24 h in saline solution at room

temperature. A push-out test was performed using a universal testing machine

(shimidzu ag-5000e) with a crosshead speed of 0.5 mm/min. The results of one

way anova bivariate testing showed that the total-etch and self-etch systems have

comparable adhesion capability (p0.05). With easier application, the self-etch

system has a comparable adhesion capability to the total-etch system.41

38. A study was done to compare the fracture resistance and failure mode of

endodontically treated teeth restored with three different post systems for which

thirty-six maxillary canines were randomly divided into three groups (n=12). All

teeth received endodontic therapy and one of three post systems of cast post-and-

core, zirconia fiber post, and quartz fiber post. Cast posts-andcores were cemented

using zinc phosphate cement, fiber posts were luted with dualcured resin cement,

and composite cores were prepared. Compressive load was applied at a 135° angle

to the long axis of the tooth at a crosshead speed of 1mm/min until fracture

occurred.The mean values (SD) for fracture resistance were 1631(803), 513(348)

and 789(390) N in the cast post-and-core, zirconia fiber post and quartz fiber post

groups, respectively. Teeth restored with cast posts-and-cores exhibited

significantly higher resistance to fracture .There was no statistically significant

33

difference in fracture resistance between the zirconia fiber and quartz fiber post

groups. Fracture mainly occurred in the composite cores of these groups. They

concluded that the fracture resistance of cast post-and-core was significantly

higher than zirconia and quartz fiber posts; however, the failure mode was more

favorable in teeth restored with fiber post.42

39. A study was done to compare the fracture resistance of endodontically treated

teeth restored with posts and cores systems with different post lengths.Sixty

extracted intact canines were randomly divided in 6 groups of 10 teeth each, as

follows: groups 1, 2 and 3 were restored with custom cast post-and-core, and

groups 4, 5 and 6 were restored with prefabricated post and composite resin core,

with different post lengths (5.0, 7.5 and 10 mm, respectively). A compressive load

was applied at a 45-degree angle to the long axis until failure occurred. The results

showed statistically significant difference between the groups (p<0.001).

However, when the mean fracture forces for the groups were compared,no

significant differences could be detected among the three groups restored with

prefabricated post and group.They concluded that an increased post length in teeth

restored with prefabricated posts does not significantly increase the fracture

resistance of endodontically treated teeth. On the other hand, endodontically

treated teeth restored with custom cast-post and core showed significant increase

on fracture resistance when the post length is increased.43

40. A study was done to compare the effect of three different post systems cemented

with different systems on root fracture.Seventy‑five extracted human maxillary

34

canines with single and straight roots were used in this study. After the crowns

were removed, root canals were prepared with Reciproc R50 files. Smear layer of

roots were removed using EDTA followed by 5.25% NaOCl and distilled water.

All the root canals were filled with cold lateral compaction technique using AH

Plus root canal sealer and gutta‑percha. Samples were stored at 37°C and 100%

humidity for 1 week and then post space was prepared using fiber post drills. The

roots were then randomly divided into five groups according to the luting cements

and post systems: negative control, positive control, glass fiber post [Unicore®

(Ultradent, Salt Lake City UT, USA)] + composite core [Grandio SO (Voco

GmbH, Cuxhave, Germany)], glass fiber post [Unicore] + Rebilda post‑core

system, individual cast post core. A load was applied on the crowns of all teeth at

135° to their long axis until fracture occurred. Statistical analysis was done using

one‑way analysis of variance (ANOVA) and post‑hoc Tukey test for which the

results showed that there was statistically significant difference between the

groups. According to the post‑hoc Tukey test, cast post core (1949.35 + 316 N)

showed statistically significantly higher fracture resistance than all the groups

except Unicore + Rebilda post‑core systems (1722.48 + 144.0 N) thus concluding

that Fiber post core system which is an alternative to cast post core systems

increased the fracture resistance of the canines with root canal treatment. While

irrepairable catastrophic fractures might be seen in cast post‑core systems,

separations between composite resin core, and root interfaces might be seen in

teeth restored with fiber post‑core systems.44

35

MATERIALS AND METHODS

MATERIALS USED:

Tooth preparation:

• Diamond disc

• Micro-motor NSK EBB75900

• Vernier Caliper Gauge

• Endo Access Bur ( Size no 1)-Dentsply

• Straight hand piece (NSK EX - 6) S.No: F6X44766; Japan

Cleaning and shaping:

• K-files (Dentsply M-Access 25mm Switzerland

Size 10 , Size 15, Size 20

• PROTAPER GOLD Rotary File 25mm Lot No:1586250(Dentsply)

• X-Smart Serial No.00013514(Dentsply Maillefer)

• Mini Endo Block (Dentsply Maillefer, Ballaigues)

• Sodium Hypochlorite 3% (Venson India , Bengaluru)

• Gylde File Prep Root Canal Conditioner-15% EDTA & 10% Urea peroxide

(DeTrey Dentsply ,Konstanz,Germany)

• Saline (FRESENIUS KABI NORMAL SALINE- 9 g/L Sodium Chloride )

• Endo Activator (Dentsply Maillefer) Lot No 1539597

• Irrigator Tips-31 Gauge (Ultradent)

36

• Smear clean 17% EDTA Liquid

Obturation:

• ProTaper Gutta – Percha points (Dentsply Maillefer, Ballaigues) F3 size

• AH Plus Root Canal Sealing Material -Dentsply

• Root Canal Pluggers Standard Set RCPS6-GDC

• Ball Burnisher - (Bb22/23) GDC

• Cotosol F (Temporary Cavity Filling Material)-COLTENE

• G.P. Holding tweezer (EPL1S) GDC

Post endodontic restoration: Fiber Posts Tested

• Prefabricated glass fiber post -Tenax Fiber Trans Cat No TFT13 (COLTENE

WHALEDENT.Inc.)

• Edelweiss Post & Core (Edelweiss dentistry -Austria)

Luting Cements & Core Build UP

• Conditioner 36 - Dentsply Sirona (DeTrey)

• Prime & Bond NT(Nano technology dental adhesive ) Dentsply

• Self cure activator (Dentsply Sirona)

• Silane coupling agent(Ultradent.INC)

• ORO Micro Applicator Tips -Black

• Core-X flow Dual Cure Core Build-Up Material(Dentsply Sirona )

• Valo Ortho LED Curing light Unit (Ultradent)

• Composite instrument (LM ARTE SET )

37

• RR Cold Cure (DPI, Mumbai)

• Flexceed Putty And Kit -Rubber Base Impression Material (GC)

• Glass slab

• Spatula

Fracture Resistance Test:

• Universal testing machine

(Mecmesin, MultiTest-i systems -United kingdom )

38

METHODOLOGY

PREPARATION OF SAMPLES :

FORTY human permanent mandibular premolar teeth extracted for Orthodontic

purposes from The Department of Oral and Maxillofacial Surgery, V.S Dental

College & Hospital and Dental clinics in and around Bangalore were included . The

extracted teeth samples were cleaned with periodontal curette and stored in 0.5%

Chloramine - T solution. Teeth used in the study was stored for less than six months .

SELECTION CRITERIA

Inclusion criteria

Straight roots

Fully developed root apices

Intact clinical crown

Single root and single canal

Exclusion criteria

Cracked tooth

Decayed tooth

Endodontically treated tooth

Presence of calcified canals

The selected teeth had a single canal and straight roots. In the tooth samples, crown

was sectioned horizontally 2mm above the cemento enamel junction using a double

39

sided diamond disk and the samples were standardized to a minimum length of 14-15

mm.

The teeth samples were divided into 2 groups.

SPECIMEN GROUPING

The tooth samples were then divided into two groups of twenty teeth in each group

(total 40 samples)

• GROUP 1 -For Glass Fiber post and seperate composite resin core build up-

TENAX FIBER POST TRANS (20 samples) and composite core build up

with DUAL CURE composite resin (CORE X FLOW -DENTSPLY)

• GROUP 2-Resin composite post and core single unit -EDELWEISS POST

&CORE (20 samples)

ROOT CANAL PREPARATION

In all the 40 samples the canal patency was checked and working length was

determined with 10 K- file. For standardization of the working length the file was

introduced into the canal until it was seen at the apex and 1mm was reduced and

taken as working length. The cleaning and shaping of the canals were done using

crown down technique with rotary ProTaper Gold files till F3 size(30/9%taper). The

canals were irrigated frequently with 3% sodium hypochlorite and 17% EDTA and

finally rinsed with saline.The canal was then dried and the obturation was done using

single cone obturation technique with Protaper Gutta-Percha points-size30 (30/.09-

40

Dentsply) and AH Plus sealer(Dentsply)and sealed with provisional filling material

(Cotosol F -COLTENE) to a depth of 3mm .All the specimen were stored in 0.5%

Chloramine T for 24h for the complete setting of the cement. The quality of

obturation was checked with a radiographic.

POST SPACE PREPARATION AND CEMENTATION

The obturation material was removed to 9 mm using peeso reamer size #1, #2, #3 and

# 4 (maximum diameter of working portion -1.3mm) for glass fiber post (Tenax fiber

post Trans). For group 2 the Edelweiss group the manufacturer recommended drill

was used. The width of the Edelweiss drill was 1.4mm at the apical tip and length was

9mm .The canals were then shaped with finishing drills for both the groups .The

length of obturated apical gutta percha was maintained at 5 to 6mm for apical seal.

After completion of post space preparation the canal were irrigated with 5ml of 17%

EDTA solution for 1 minute followed by 5 ml of 3 % NaOCl solution for one

minute.Then 2ml saline was used for one minute to cease the irrigant activity and then

dried with paper point. Trial fit of both the glass fiber post and edelweiss post and

core single unit was checked radiographically .

CEMENTATION OF GLASS FIBER POST (TENAX FIBER POST TRANS):

CONDITIONING STEP:

The post space was etched with 36% phosphoric acid (DeTrey Conditioner 36 -

Dentsply Sirona) with disposable steel cannula locked over the end of the syringe and

dispensing tip bent for easy access. The blue tinted gel flowed freely into the post

space as well as the coronal tooth structure for 20 seconds. After 20 seconds the

41

conditioner was removed and thoroughly rinsed with water.This was followed by

blot drying with sufficient paper points and cotton pellets in the post space

preparation.Care was taken not to desiccate the dentin.

BONDING STEP:

Using the disposable brush or applicator tip, generous amounts of equal drops of

Prime & Bond® NT™ and self cure activator (Dentsply) dual cure adhesive was

applied thoroughly to wet the post space and remaining coronal tooth surface for

about 20 seconds .Silane coupling agent was applied on the post surface and excess

solvent was removed by gently drying with clean, dry air from the surface of the post

so that the surface has a uniform glossy appearance .The excess solvent was removed

from the root canal space by using paper points followed by light curing of the post

space and remaining coronal structure with Ultradent’s Valo Ortho LED Curing light

Unit 1000mW/cm2 for 20 seconds.

CEMENTATION STEP:

Dual cure restorative cement Core X flow was dispensed directly from the syringe

onto the post surface and to the orifice of the post space preparation , remaining

coronal tooth structure and the post was placed into final position and stabilized and

cured from all sides for 60 seconds with Ultradent Valo Ortho LED Curing light Unit

1000mW/cm2 .

42

CORE BUILD UP :

Core build-up was done with Dual cure highly filled composite resin(CORE X FLOW

-DENTSPLY) in all the 20 samples of glass fiber post and all the samples were

standardised to a core length of 5.5mm and width of approximately 5mm.

CEMENTATION OF EDELWEISS POST AND CORE SINGLE UNIT

After the conditioning step of the post space,the bonding step was carried out using

Prime and Bond NT as described earlier.

For Edelweiss post and core single unit Edelweiss veneer bond was

applied instead of silane coupling agents on the post surface and excess solvent was

removed by gently drying with clean, dry air from the surface of the post so that the

surface has a uniform glossy appearance and excess solvent was removed from the

root canal space by using paper points followed by light curing of the post space and

remaining coronal structure with Curing light Unit 1000mW/cm2 for 20 seconds(Valo

from Ultradent). Dual cure restorative cement Core X flow was dispensed directly

from the syringe onto the post surface and to the orifice of the post space preparation

and remaining coronal tooth structure and post was placed immediately into final

position and stabilized and cured for 60 seconds with Ultradent Valo Ortho LED

Curing light Unit 1000mW/cm2.Any deficient area between the tooth samples and the

core was compensated with Core X Flow to form a uniform core of 5mm.

43

MOUNTING THE SAMPLES

The tooth samples were mounted on acrylic block with polyvinylsiloxane

impression material to simulate the effect of periodontal ligament.

The root surface of all the samples were coated with thin layer of

glycerine with the applicator tips for the ease of removal of the tooth after the

polymerisation of the acrylic block. The tooth was embedded in individual block of

self cure acrylic resin measuring 2.1x2.1x2.7cm 3 with long axis perpendicular to the

base of the acrylic block and acrylic ending at 2mm below the cementoenamel

junction After polymerisation of the acrylic resin the roots were carefully removed.

Siloxane impression material was injected according to manufacturers instruction into

the mould space and the tooth was reinserted .The excess impression material was

removed .This was done to simulate the periodontal ligament .

THERMOCYCLING OF ALL THE SAMPLES

All the 40 samples were subjected to manual thermocycling (servological water bath)

for about 1000 cycles at 5o c and 55o c with a dwell time of 30 seconds. After the

thermocycling the samples were subjected to fracture resistance with the Universal

Testing Machine.

FRACTURE RESISTANCE TEST

Fracture resistance was performed by the Universal Testing Machine with the

specimen mounted on retaining arms of the machine . The load tip was placed 135

degree horizontal plane on to a standard marking made in the middle of the lingual

44

occlusal line angle of the core and a continuous compressive forces was applied with

a cross head speed of 0.5 mm/min till fracture .The point of fracture was determined

by a sudden drop of the applied force and an audible crack .The fracture force was

recorded in newtons . The mode of failure of all specimen was viewed under

stereomicroscope at 20x magnification.

MODE OF FAILURE :

The mode of failure of all the samples were categorised as root fracture,core

fracture,tooth fracture, post debonding and post fracture .

Root fractures were considered as catastrophic fractures while core

fracture, debonding of post, post fracture and tooth fracture were considered as non

catastrophic fractures.

45

SAMPLE SIZE OF ESTIMATION

Sample size

n =2× (𝑍𝛼

2+𝑍𝛽)2

𝑑2× 𝑆𝐷2

Z α/2 =Type 1 error (5%) =1.96

Z β = Type1 error (10%) =1.28

SD =Standard deviation =0.5( From literature)

d =minimally detectable difference=0.4

n=2× (1.96+1.28)2 ×0.52

( 0.4)2

=2× 10.49 ×0.25 = 32.78 ≈ 40

0.16

46

RESULTS

During mechanical loading of the samples, it was determined that initial failure of

post and core will be recorded .The initial failure load was designated as the first drop

in the load values.

Data was analysed using the statistical package SPSS19.0

(SPSSInc.Chicago,IL) and the level of significance was set at p<0.05.Descriptive

statistics was performed to find the mean and standard deviation of respective groups

.Independent t test was used between the groups to find out the significance.

Analysis indicated significant difference among the two

groups (p<0.035) by independent t test . The glass fiber post (Tenax fiber post Trans)

exhibited a mean failure load of 1089.234±225.324. N and Edelweiss resin composite

post and core single unit with a mean of 1305.419±327.689 N. The lowest mean

strength was obtained for glass fiber post (Tenax fiber post trans) and highest mean

strength was obtained for Edelweiss resin composite post and core single unit

The mode of failure was assessed in case of glass fiber post.The

results showed a total core fracture of 9 among the 20samples (45%),post debonding

of 6 out of the 20 samples (30%),post fracture of 3 out of 20 samples(15%)and tooth

fracture and root fracture of 1each among 20 samples(5% each) .

ie. Non catastrophic fracture constituting of about 95% while Catastrophic fracture of

5%.

In case of Edelweiss resin composite post and core single unit

showed a total core fracture of 17 among the 20samples (85%).The number of tooth

fractures seen was 3 out of the total 20 samples(15%) subjected to fracture

47

ie. Non catastrophic fracture constituting of about 100% while Catastrophic fracture

were not seen in this group.

*P<0.05 is statistically significant

TABLE SHOWS MEAN AND STANDARD DEVIATION OF FRACTURE

RESISTANCE (N) IN TWO GROUPS.

Higher value observed in Edelweiss post group(1305.419±327.689) and Glass

fiber post showed a value 1089.234±225.324.

The statistical test using independent t test revealed a statistical difference

between the group regarding the fracture resistance.(p<0.05)

Table -1 COMPARISON OF FRACTURE RESISTANCE

Group

Mean

SD

P VALUE(independent

t-test)

Glass Fiber Post

(Fracture resistance)

1089.234 225.324

0.035 (t=2.1801)*

Edelweiss post

(Fracture resistance)

1305.419 327.689

48

• The glass fiber post group showed 9 core fracture,6 post debonding,3 post

fracture,1 tooth fracture and 1 root fracture

• The Edelweiss post and core single unit reported 17 core fracture and 3

tooth fracture

TABLE SHOWS THE DIFFERENT FAILURE MODE SEEN IN THE TWO

SAMPLE GROUPS

TABLE 2-FAILURE MODE ANALYSIS

Group

POST

DEBONDING

POST

FRACTURE

CORE

FRACTURE

TOOTH

FRACTURE

ROOT

FRACTURE

Glass

Fiber Post

(Fracture

resistance)

6 3 9

1 1

0 Edelweiss

post

(Fracture

resistance)

0 0 17 3

49

GRAPH 1- COMPARISON OF FRACTURE RESISTANCE

GRAPH 2- FAILURE MODEL ANALYSIS-PERCENTAGE WISE

DISTRIBUTION

0

200

400

600

800

1000

1200

1400

mean sd

1305.419

327.689

1089.234

225.324

Edelweiss post (fracture resistance) Glass Fiber Post (Fracture resistance)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

Postdebonding

post fracture core fracture tooth fracture root fracture

30%

15%

45%

5% 5%0 0

85%

15%

0

Glass fiber post (fracture resistance Edelweiss post(Fracture resistance)

50

TABLE-3

TABULATION OF THE SCORES OBTAINED AFTER FRACTURE

TESTING & FAILURE PATTERN

GLASS FIBER POST

EDELWEISS POST AND CORE

SINGLE UNIT

1205.9(CORE FRACTURE) 1605.2(CORE FRACTURE)

1384.3(CORE FRACTURE) 1115.7(TOOTH FRACTURE)

1129.5(CORE FRACTURE) 1241.2(CORE FRACTURE)

1867.8(POST DEBONDING) 1398.8(CORE FRACTURE)

1207.7(CORE FRACTURE) 955.5(CORE FRACTURE)

1195.4(CORE FRACTURE) 1261.0(CORE FRACTURE)

763.3(CORE FRACTURE) 2145(CORE FRACTURE)

1508(ROOT FRACTURE) 1081.4(CORE FRACTURE)

1164.5(POST DEBONDING) 1409.3(CORE FRACTURE)

1211.1(POST DEBONDING) 816.2(CORE FRACTURE)

1587.7(CORE FRACTURE) 1836.5(CORE FRACTURE)

1394.4(POST FRACTURE) 1296.4(CORE FRACTURE)

730.5(CORE FRACTURE) 1157.8(CORE FRACTURE)

953.3(TOOTH FRACTURE) 1505.7(CORE FRACTURE)

1004.3(POST FRACTURE) 952.9(TOOTH FRACTURE)

792.6(POST DEBONDING) 1250.64(TOOTH FRACTURE)

1023.45(CORE FRACTURE) 1358.43(CORE FRACTURE)

922.32(POST DEBONDING) 1240.41(CORE FRACTURE)

1092.31(POST FRACTURE) 1617.9(CORE FRACTURE)

824.65(POST DEBONDING) 862.8(CORE FRACTURE)

51

TABLE -4

TABULATION OF FAILURE PATTERN SEEN IN THE TWO GROUPS:

GLASS FIBER POST

(TENAX FIBER POST TRANS)

GROUP 1

EDELWEISS POST AND CORE

SINGLE UNIT

GROUP 2

ROOT FRACTURE

5%

ROOT FRACTURE

0%

CORE FRACTURE

45%

CORE FRACTURE

85%

POST DEBONDING

30%

POST DEBONDING

0%

POST FRACTURE

15%

POST FRACTURE

0%

TOOTH FRACTURE

5%

TOOTH FRACTURE

15%

52

DISCUSSION

The present study was done to compare the fracture resistance of endodontically

treated teeth restored with glass fiber reinforced composite post (Tenax Fiber post

Trans) and core( Core Build up Material – Dual cure Core-X Flow) versus laser

sintered nanohybrid composite post and core single unit (Edelweiss post and core

unit).

The 40 teeth used for the study was extracted and stored in 0.5% chloramine T

solution and the tooth samples used was less than 6 months old according to ISO/DTS

11405.45

The prognosis of endodontically treated teeth depends

not only on the treatment itself, but also on sealing the canal and minimizing the

leakage of oral fluids and bacteria into peri radicular areas by prompt placement of

coronal restorations.16 This treatment includes the decision of whether or not posts

should be used.16 For many years post and core system have been used as

foundational material for final restoration of endodontically treated teeth that have

lost most of their coronal tooth structure .Posts should have the ability to allow force

and stress transfer distribution to prevent root fracture.15,17

Peroz et al in 2005 describes the lost tooth structure as

Class I when access preparation with all 4 axial cavity walls is remaining. Class II

describes loss of 1 cavity wall, commonly known as the mesio-occlusal (MO) or the

disto-occlusal (DO) cavity. Class III represents an MOD cavity with 2 remaining

cavity walls. Class IV describes 1 remaining cavity wall, in most cases the buccal or

lingual wall, and Class V describes a decoronated tooth with no cavity wall

remaining. The minimal thickness of the cavity wall as a determining factor for the

53

resistance to functional loads of the crown-root complex is considered as 1 mm.46

Hard tissue with thicknesses below this level cannot be prepared for full crowns . A

thickness greater than 1 mm provides an amount of hard tissue sufficient to stabilize

the core material even after crown preparation.

The minimal height of a cavity wall capable of

providing a sufficient ferrule effect is 2 mm. No post is needed in cases with at least 2

axial cavity walls remaining.46A post should be inserted if only 1 cavity wall is

remaining and when there is no cavity wall remaining, but a ferrule of 2 mm is needed

to provide a lower risk of root fracture.46

Historically, the most commonly used post and core

system was cast metal posts.They remained as the treatment of choice in post

endodontic situations till date for most dentists. However, they fail twice as often as

prefabricated metal posts, and may also result in catastrophic root fractures.3

Pre fabricated Post System

Prefabricated polymerised fiber-reinforced composite

post have been avaliable from1990s .These composite materials are composed of

fibres of carbon or silica surrounded by a matrix of polymer resin, usually an epoxy

resin.The modulus of elasticity of fiber reinforced composite posts is in the range

similar to that of dentin(16 GPa to 40 GPa). Therefore, the masticatory forces are

gently transmitted from the restoration to the core build up and the post of the tooth.

In contrast, metals have a considerably high modulus of elasticity, which promotes the

transmission of stress to the root canal wall.84. Among the variety of posts available

the carbon-fibre posts are black in colour and do not lend themselves to aesthetic

restorations with all-ceramic units. This led to the introduction of the silica-fibre posts

54

which are translucent and more tooth coloured. These posts are categorised as glass-

fibre and quartz-fibre post. It has been suggested by manufacturers that these posts

retain similar physical properties to carbon-fibre posts.47

Glass fiber post system

The glass fiber post contain pre stretched silanized glass

fibers bounded by methacrylate or epoxy-polymer matrix with high degree of

conversion and highly cross-linked structure that binds the fibers.48The fibers offer

strength and stiffness, while the polymer matrix transfers forces to the fibers and also

protects them from the moisture of the oral environment.49

The mechanical properties of prefabricated FRC posts

depends on the type of fibre used, the type of matrix used, the fibre content, and the

direction of the fibres.50The fibres contribute stiffness and strength to the usually

elastic matrix . Epoxy resins and BisGMA are usually used as a resin based material

for dental fiber posts . E-(electrical application) and S-(stiff, strong) glass fibers have

become the most commonly used reinforcing fibers. Glass fibers stretch uniformly

under stress to their breaking point and on removal of the tensile load short of

breaking point, the fiber returns to its original length.

These posts have excellent esthetic properties, flexural

and fatigue strength and a modulus of elasticity similar to that of dentin. The modulus

of elasticity of FRC posts provide elevated shock resistance, weakening of vibration

effect, shock absorption, and augmented fatigue-resistance.51 Glass fiber post are easy

to handle allowing one-visit therapy.They have excellent biocompatibility and are of

low cost.They can be retrieved easily during retreatment.

55

A study by Shweta Sharma et al 2016 compared the

fracture resistance of glass fiber post ,carbon post and quartz fiber post and

concluded that Quartz, carbon, and glass fiber-reinforced posts show good resistance

to fracture, and hence can be used in endodontically-treated teeth.52A study done by S

Vidhya et al 2009 compared the fracture resistance of Everstick post , glass fiber post

and carbon fiber post and concluded that although EverStick posts showed maximum

bonding resin penetration, which has clinical implications in achieving a good coronal

seal the fracture resistance values was less than other posts.53

A study done by Érico Braga Franco et al 2014 evaluated the

influence of glass fiber post and cast post on the fracture resistance of endodontically

treated teeth and concluded that for teeth restored with glass fiber posts, the failure

occurred at the junction between the composite resin core and the post.Cast post,

though having significantly greater fracture resistance than glass fiber posts had more

of catastrophic fractures.30On esthetic considerations, the cast metallic post can result

in discoloration and shadowing of the gingiva at the cervical aspect of the tooth.

Moreover, they require two appointments with added laboratory fee.12

Thus, for the current study glass fiber post (Tenax fiber post

Trans) was used. The TENAX® Fiber Trans™Post System is a high quality,

translucent glass fiber resin post system, that has a tapered design in the root end third

of the post.It is a cylindro-conical, passive post system. It is a great alternative for

esthetic, metal-free restorations.54 Its available in various sizes 1.1mm,1.3mm,1.5mm

For the other group the recently launched single unit Edelweiss post

and core system was used. These post and core units claim to have better physical

properties than the fiber post.

56

Features of Edelweiss post & core system single unit

The Edelweiss POST & CORE system is a laser sintered nanohybrid

composite monobloc. The posts have a conical shape for perfect post space

adaptation.The translucency of the fibre free post, supported by the lens design,

allows uninterrupted light transmission for complete polymerization of the luting

cement resulting in a single monobloc between the adhesive layer and composite

post.This is supposed to avoid the wedging effect.The core has a similar feel to that of

the natural tooth and makes handling easier.55 The post and core unit also possesses

antibacterial properties owing to the incorporation of zinc oxide nanoparticles.

It is manufactured by selective laser sintering (SLS) by additive

manufacturing (AM) process for fabricating three-dimensional (3D) objects by adding

powdered materials layer-by-layer according to computer-aided design (CAD). Laser

sintering of the material results in a homogenous, inorganic, and high gloss laser

vitrified post surface which is then fused with a sintered and thermally tempered

(3000C) dynamic composite core.This produces an optimal integration between

function and esthetics.The aesthetic property is unique because a translucent post

attached to an opaque built-in core.55

Since the post and core is a homogenous monoblock the

manufacturer’s claim that there is no possibility of debonding of the core from the

post. Light transmission throughout the full length of the post is enhanced by the

post’s translucency because of the vitrified glass-like layer on the surface which

enhances the optical properties.This ensures complete polymerisation of the luting

57

cement. They claim that its strength is similar to that of lithium disilicate and its glass-

like surface has similar optical properties to those of ceramics which benefits the

clinician.55,56Its flexural modulus is 20 GPa like Dentin (15 – 20 GPa), flexural

strength is 200MPa and compressive strength of 550MPa and surface hardness is

95HV and the post and core system is radio-opaque.Edelweiss post and core single

unit is available in 7 forms :upper anterior, upper premolar, upper molar ,lower

anterior ,lower premolar and lower molar and also an universal post without the

core.55 The post and core system used in this study is of the mandibular premolar with

post length of 9 mm an apical diameter of 1.4mm .The core dimensions include an

incisocervical length of about 5.5mm and mesial-distal width of 5mm .55

Effect of ferrule on fracture resistance of tooth

In the present study the samples were decoronated 2mm above the

cemento enamel junction . A ferrule is composed of parallel walls of dentin from the

crown’s margin extending coronally to the fractured part of the tooth.57 Studies have

demonstrated that a minimum ferrule height of 1.5-2 mm shows improvement in the

longevity of endodontically treated teeth restored with post and core and also provides

better fracture resistance.58 It is stated that the glass fiber post and a built-up core

concentrated stresses at the cervical level hence, the stress distribution to dentin in this

region is higher. However, when the ferrule effect exists, the fiber post has less

tendency to bend .59 Also when taking the height of the ferrule into consideration

some studies showed that the presence of a ferrule of 1.5 to 2 mm height was more

important for fracture resistance than the post type or post design as the tooth with a

cervical ferrule presents a coronal displacement of the fulcrum line, decreasing the

effect of flexion (bending moment) and protecting the specimen.60 The influence of

58

ferrule thickness on clinical outcome is also a topic that needs to be explored. Tjan

and Whang et al 1985 reported that there was no significant difference among the

groups that had remaining buccal dentin of varying thickness of 1 mm, 1 mm with a

60 degree bevel, 2 mm, and 3 mm. However, a dentin thickness of 1 mm resulted in a

higher incidence of failure due to fracture rather than cement failure.61 Joseph and

Ramachandran et al 1990 studied the effect of thickness of coronal dentin and

concluded that fracture resistance increased in case of 2-mm-thick remaining dentin.59

In the current study, the teeth samples were decoronated and prepared

so as to have so as to have a ferrule with a height of 2 mm and a minimum width of

2mm.

Root canal treatment procedure

The selection of the post system and standardisation of the root length

for all the samples were done .The root canal treatment was initiated in all the samples

after working length was determined followed by biomechanical preparation with

Protaper gold instrument upto size F3(30/.09).The canals were intermittently irrigated

with 3% sodium hypochlorite and 17% EDTA and finally rinsed with saline followed

by obturation with single cone obturation technique with gutta percha and AH plus

sealer .The samples were subjected to post space preparation after 24 hours of storage

in 0.5% chloramine T solution.

Fernando Solano et al 2005 explains that AH Plus sealer is a

resin sealer and has an 8 hour setting time.In their study they did not delay the post

space preparation.They explained that delayed post space preparation after final set of

sealer may cause movement of the gutta-percha due to rotational forces of Gates

59

Glidden drills and may result in breaking the bond at the sealer interface62.Portell et

al. (1982) , Fan et al. (1999) , and Kwan and Harrington (1981) were in agreement

with Fernado Solano et al 2005 and showed significantly less leakage when post

spaces were prepared immediately after obturation. In contrast, the studies by

Madison and Zakariasen (1984) , Bourgeois and Lemon (1981), and Abramovitz et al.

(2000) said that there was no difference between immediate versus delayed post space

preparations.62

In this study the post space preparation was done 24 hours after

obturation considering the setting time of the AH plus sealer and in accordance with

the studies done by Madison and Zakariasen et al , Bourgeois and Lemon et al and

Abramovitz et al.

Post space preparation procedure for glass fiber post :

For the post space preparation the obturation material was removed

to 9 mm using peeso reamer #1, #2, and #3 and # 4 (1.3mm) for glass fiber post

(Tenax fiber post Trans) and for the Edelweiss group the manufacturer recommended

drill was used. The apical gutta percha was maintained at 5 to 6mm to provide apical

seal.

Post space preparation drills for Edelweiss post and core unit :

The manufacturer recommended drills were used in this study which

had the following features :The drill had more cutting edges designed to improve

efficiency which allows inward progression of drill flutes designed to allow debris out

60

of the canal . It has solid center core to maintain centrality within the canal and allows

for ideal post fit .It has tapered post design to follow canal anatomy and stepped

cutting tip for enhanced cutting and shaping of post space. The post drill used in the

study has a diameter of about 1.4mm.55

A review article by Goodacre and Spolnik in 1995

recommends post length equal to 3⁄4 of root canal length if possible, or at least equal

to the length of the crown. They caution that 4 to 5 mm of gutta-percha should remain

apically to maintain an adequate seal.63 In a retrospective study, Sorensen and

Martinoff 1984 reported 97% success if the post length at least equalled the crown

height.64 According to Neagley et al 1964,8 mm is the minimum length required for a

post.65 Hunter et al in 1989 has shown that forces concentrate at the crest of bone

during masticatory function and recommend that a post should always extend apically

beyond the crest of bone.66

A study done by Érico Braga Franco et al 2014 explained that

post length, although important for the mechanical behaviour of metal posts, did not

significantly influence the resistance to shear load for glass fiber post.30 Another study

by Shurooq S. Abdulrazzak et al 2013 tested the fracture resistances of endodontically

treated maxillary central incisors with different post lengths and three different ferrule

heights.They confirmed that endodontically treated teeth with the presence of a ferrule

was superior in the prevention of tooth fracture under a static load regardless of the

post length. Results indicated that increasing the ferrule height significantly increased

the fracture resistance of endodontically treated teeth .The most reasonable

explanation given by them is that when the amount of remaining dentine increases, it

allows for redistribution and dissipation of large forces. Besides, more coronal dentine

61

structure form a more stable foundation for the post and core with greater resistance to

rotation could be achieved.The study also found no significant differences between

the mean failure loads for the three post lengths used in each of the three ferrule

height groups. These findings may be due to the fact that the effect of ferrule was

masking the effect of post length. It was also confirmed that the ferrule length was

more important than the post length in terms of enhancing the fracture resistance of

crowned teeth and increasing the post length did not significantly increase the fracture

resistance of endodontically treated teeth restored with prefabricated glass fiber

posts.25

A study by Necdet Adanir et al 2008 revealed that increased post

length also increases risk of fracture and perforation of the remaining root especially

when dowel length is increased beyond two thirds of the root.They found that when

stresses in the apical region increase post length extension may damage the root apical

sealing. In this respect, the apical 3 to 6 mm of gutta-percha must be preserved to

maintain the apical seal. No significant difference in retention of posts with 8 mm and

10mm lengths was observed in their study.26According to traditional teachings, a

minimum of 3 to 5 mm of gutta-percha should remain in the apical portion of the root

to maintain an adequate seal .A study by Abramovitz et al. in 2001 demonstrated that

3 mm of gutta-percha provides an unreliable apical seal, therefore, 4 to 5 mm is

recommended.67 In the current study 9mm post length for both the glass fiber post and

edelweiss composite post , was selected in accordance with the previous studies done

by Shurooq S et al (2005) and Necdet Adanir et al 2008 and 4-5mm apical GP was

retained for apical seal.

62

Irrigation protocol for post space:

The post space was irrigated with 5ml of 17% EDTA solution for 1

minute followed by 5 ml of 3 % NaOCl solution for one minute and then 2ml saline

was used for one minute to cease the irrigant activity and then the post space was

dried using paper point.

A study done by Rahele Mirseifinejad et al 2017 compared the

effect of different irrigants on smear layer removal after post space preparation and

concluded that 17% EDTA+5.25% NaOCl is an effective irrigant for smear layer

removal after post space preparation.33

A study was done by Daniel Poletto et al 2017 to evaluate the smear layer

removal with chemical solution with or without ultrasonic activation after post space

preparation. Poletto explained that 17 % EDTA with 2.5% sodium hypochlorite was

required for the effective removal of smear layer.The study also explained that

ultrasonic activation had no effect on the secondary smear layer removal after post

space preparation.69

In the current study 17% EDTA and 3% of sodium hypochlorite

was used in accordance with the results of the study of Daniel Poletto et al 2017.69

Cementation of the post systems:

1. Etching & Bonding

Bonding to dentin may be achieved using etch-and-rinse (i.e.

total-etch) and self-etch adhesives with conventional resin cement or self adhesive

cement.

Total etch adhesive system involves the application of etching

solution with a rinsing and drying procedure for priming, application of a bonding

63

agent, and then a cementation procedure with resin cement. In the self-etch system,

the etching and priming solution is combined in an acidic primer, and no rinsing and

drying procedure is needed.41

In the self-adhesive system, the etching, priming, bonding, and

resin cement are combined in one component, so there is only one application

procedure. In the total etch system because of the more complex application process,

the risk of residual etching solution and water remaining in the post space is higher .

But, there is an increase of surface bonding area in the root canal after the total-

etching procedure. Application of etching solution in the total-etch system can

demineralize dentine and promote a deeper hybrid layer and resin tag formation than

the self-adhesive system. In the self-adhesive system, a smear layer on the dentine

surface is often not cleaned completely, so the hybrid layer and resin tag formation is

more superficial.41

The total-etch system is a technique-sensitive procedure

because of the high risk of over wetting and overdrying during the rinsing and drying

procedure after application of etching solution. The application of etching solution

removes the smear layer, demineralize hydroxyapatite inorganic matrix, and then

expose collagen fibers and dentinal tubules. Good bonding is formed when monomers

in the bonding agent penetrate dentinal tubules and collagen fibers, forming a good

hybrid layer and resin tag. If the drying procedure after etching and rinsing is not

complete, the dentine would be wet or overwet. On wet dentine, monomer penetration

to dentine tubuli and collagen fibers would be easily dissolved because monomers

tend to be hydrophilic. The dissolved monomers would cause failure of hybrid layer

and resin tag formation, resulting in bonding failure. If the drying procedure after

etching and rinsing is excessive with overdrying, the collagen fibers would be fragile

64

and broken with decreased permeability. As a result, monomers in the bonding agent

would not penetrate to collagen fibers and dentine tubules, so hybrid layer and resin

tag formation would fail, resulting in bonding failure.

The self-adhesive system has three weaknesses that can lead

to bonding failure. The first weakness is in the use of one component that is a

combination of components. It is difficult to maintain a stable combination of some

chemical components for a long time. Secondly the self-adhesive system has a high

composition of water that tends to hydrolyze and cause chemical reaction failure,

especially during exposure to the high temperatures that occur during the application

process. Its hydrophilic character, also can dissolve adhesive sometime after

application and polymerization on dentine. The third weakness in the self-adhesive

system is that the acidic composition of the adhesive compound relies on a self-cured

and dual-cured polymerization system. Acid can degrade the tertiary aromatic amines

that are needed for chemical polymerization. These weaknesses could explain why the

self-adhesive system had the lowest adhesive capability among the adhesive

systems.41

Goracci et al 2005 reported that the interfacial strength and

ultrastructure of total-etch, self-etch and self-adhesive resin cements (Variolink II,

Panavia 21 and RelyX Unicem) used for luting endodontic glass fiber posts was

assessed with the "thin-slice" pushout test and transmission electron microscopy

(TEM). The values achieved by Variolink II (total etch )were significantly higher than

Panavia and RelyX Unicem. TEM analysis revealed that the acidic resin monomers

responsible for substrate conditioning in Panavia 21 and RelyX Unicem(self etch and

self adhesive cement respectively) did not effectively remove the thick smear layer

created on root dentin during post space preparation.The study emphasis the

65

interfacial strength and microscopic findings were in agreement and indicated that

bonding potential of the total etch resin cement was greater.70

Valandro and colleagues et al 2005 concluded that more

reliable bond strengths in the dowel space might be achieved when using multiple

bottle total-etch adhesive systems instead of self-etching adhesives .71

A study by Y Theodor et al 2017 stated that the self-etch

system is the best adhesive system for fiber post cementation. The self-etch adhesive

application was less technique-sensitive than the total-etch system because it has the

easiest application process. However, this study showed that the adhesive capability

of the self-adhesive system was lower than the total-etch and self-etch systems.41

In the current study the total etch system was followed in

accordance with previous studies by Goracci et al and Theodor et al .The post space

and the remaining dentin was etched with 36% phosphoric acid . Further bonding was

done by Prime & Bond® NT™ Nano-Technology Dental Adhesive .Prime & Bond ®

NT™ is a light-cure self-priming dental adhesive designed to bond composite

materials which combines primer and adhesive in a single container.The reduction of

components and treatment steps simplifies use, maintaining superior bond strengths

and protection against microleakage. Prime & Bond® NT™ Dual Cure bonding

system used in the study include the Prime & Bond ® NT™ and Self Cure Activator

components.72

2. Sialinization

Post adhesion in the root canal represents the weakest point of the restoration.

Bonding of fiber posts to composite materials relies on the chemical interaction

between the post surface and the resin material used for luting and building-up the

core. In an attempt to maximize resin bonding to fiber posts, several surface

66

treatments have been recently suggested : 1. silanization and/or adhesive application;

2. acid etching, sandblasting and silica coating ; 3. alternative etching

techniques(treatments that combine both a micromechanical and a chemical

component).73

Silanization and/or adhesive application represent the most

investigated surface treatment in the current literature. Several studies suggest the use

of silane coupling agents in coating fiber posts for enhancing adhesion to composite

resins.

However according to Bitter K et al 2005 with silane

treatment the clinical relevance of enhance bond strength was of minor importance.74

On the contrary, Goracci and colleagues 2005 reported an improvement in bond

strength between silanized fiber posts and flowable composite cores.75 Aksornmuang

and colleagues in 2004 confirmed the benefit of silane application in enhancing the

microtensile bond strength of a dual-cure resin core material to translucent fiber posts.

These results rely on silane capability of increasing surface wettability resulting in

chemical bridges formation with OH-covered substrates, such as glass or quartz

fibers. However, interfacial strength is still relatively low in terms of MPa. The

absence of chemical union between resin composites (methacrylate-based) and the

matrix of fiber posts (often made of epoxy resin) represent one possible

explanation.76,77

In the current study the glass fiber post was surface

treated with silane coupling agent by Ultradent and Edelweiss post and core single

unit was surface treated with Edelweiss Veener Bond.

67

3. Cementation with Core X flow and Core build up

After the sialinization the posts were cemented with Core X Flow (Dentsply).It is a

Dual Cure Core Build-Up Material used for the Cementation of Endodontic Posts.

Core-X® flow consists of two-components, base and catalyst, which when mixed

form a dual cured, highly filled, composite resin core build-up and post-cementation

material. Core-X® flow uses a biocompatible urethane resin and is supplied in a

tooth-colored shade which is ideal in situations where esthetics and show-through of

the core are of primary concern.78After the cementation of the post the core build up

was subsequently done in the glass fiber post samples so as to obtain a standard core

build up of length 5.5mm and width of approximately 5mm . In the case of Edelweiss

post and core single unit system after the cementation of the post and core unit,the

deficient areas were restored with Core X flow dual cure composite.In the edelweiss

post and core single unit the core dimension was standardised to length of 5.5mm and

mesiodistal width of 5mm approximately.

Mounting of the tooth samples in acrylic blocks

After the cemention of the two post system in their respective groups the samples

were mounted on acrylic resin block .The height and breadth of the acrylic block was

standardised to 2.1x2.1x2.7cm3. The use of rigid material to embed the extracted teeth

may lead to distorted load values and possibly affect the mode of failure of the

specimen. Therefore an attempt was made to simulate the periodontal ligament and

surrounding anatomical structures by coating the roots with polyvinyl siloxane and

then embedding the roots in acrylic resin.79

68

After this step,the samples were subjected to thermocycling.

Effect of thermocycling in a water bath

Thermocycling has been viewed as an essential aspect of dentin

adhesion testing. Thermo cycling create stress at the cementing agent-hard tissue

interface, either by differences in thermal expansion coefficients within the multi

component material or by an accelerated hydrolytic degeneration of the cementing

agent.27

David et al 2003 studied the effect of thermocycling on the retention

of glass fiber root canal posts (light post) cemented with Panavia F resin cement and

found that there were no significant differences in the forces required to cause post

retention failure between the control and thermocycling samples.80,81

In the current study manual thermocycling (servological water bath)

for about 1000 cycles at 5o c and 55o c with a dwell time of 30 seconds was carried out

on all samples .

Fracture testing :

After thermocycling the samples were subjected to universal testing machine for

determination of the fracture resistance.82The load tip of 1mm diameter was placed

135 degree horizontal plane on to a standard marking made in the middle of the

lingual occlusal line angle of the core in accordance with previous studies. A

continuous compressive forces was applied with a cross head speed of 0.5mm/min till

fracture83,84.The point of fracture was determined by a sudden drop of the applied

force and that audible crack and the force was recorded in newtons.

69

Fracture resistance of glass fiber post with other FRC post has

been already discussed in the literature . According to this Shewtha et al 2016 said

that glass fiber post has less fracture resistance than quartz fiber post.52A study done

by Sweta et al 2017 said that glass fiber post has less fracture resistance than

Everstick post system20. A study done by Ambica et al 2011 revealed that

experimental dentin post has more fracture resistance than glass fiber post.28 A study

done by Buket Ayna 2018 concluded that polyethylene and zirconia-rich glass fiber

posts were similar, suggesting that both types of fiber post can be used successfully to

help retain resin composite restorations.31 Though the studies show good amount of

fracture resistance of the fiber reinforced post system ,the literature also reveals the

less fracture resistance of glass fiber post when compared to other metallic post

system such as the cast post and titanium post and also when compared to zirconia

post .But all these post system tend to cause catastrophic fracture when subjected to

load until failure which was comparatively less in the case of glass reinforced post

system 85,86 .

In the current study the fracture resistance of the glass reinforced

fiber post with composite core and Edelweiss single unit composite post were

subjected to load until failure .The fracture resistance of the edelweiss composite post

and core system system showed a high fracture resistance when compared to glass

reinforced fiber post .The possible explanation of the high fracture resistance could be

due to resin composite material which is a nano-hybrid composite modified through a

special laser sintering and vitrification process whereby the composite becomes a

single inorganic phase, thus improving both its physical and mechanical properties.

Although the fracture resistance of glass fiber post was less than the Edelweiss post

and core single unit ,the values may not have much of a clinical significance.

70

Anusavice et al recorded in his study that the maximum bitting force is about 756N.87

The fracture resistance values of the glass reinforced fiber post were much higher than

the expected maximum bitting force stated by Anusavice.

Failure mode :

Later the failure mode of all the samples were viewed under

stereomicroscope at 20X .All kinds of failure modes were observed in glass fiber post

such as Core fracture, post debonding, post fracture,tooth fracture and root fracture.

According to the studies most of the failure associated with the

fiber reinforced composite posts are due to debonding of the posts. The debonding is

between post-cement interface rather than cement-dentin or intracemental fracture

(cohesive failure of cement). This debonding is often attributed to various causes like

most of the glass fiber reinforced composite post are made of highly cross-linked

epoxy resin which makes it difficult to bond with methacrylate based resin cement.

Other reasons might be change in physical properties such as flexural strength and

modulus of elasticity due to water sorption leading to expansion, changes in

temperature (difference in coefficient of thermal expansion of glass fiber post, dentin,

and core material), and dynamic functional loading.88 When considering fiber

reinforced post and composite core, it was suggested that resin fiber posts are

industrially cured, with a high level of polymerization and concomitant relatively

small quantities of free resin available to interact with the reactive chemical

constituents present in resin lutes or composite resin cores.89

A study done by Kiran Kulkarni et al in 2016 stated that all

failures of the fiber reinforced post were favourable, that is the post and core

71

separation or a core fracture or post fracture.12 An important limitation in

prefabricated glass fiber reinforced composite post requires separate fabrication of the

core.12 In the present study twenty samples were restored with glass fiber post (Tenax

fiber post Trans) .These samples showed a mean fracture resistance of

1089.234±225.324N. The type of fractures seen in Glass fiber post group were 45%

core fracture,30% of the post debonding,15% of post fracture,5%tooth fracture and

5% root fracture. The results obtained in the present study was in accordance with the

previous studies showing that glass fiber post group resulted in mainly non

catastrophic fractures that could be retreated.

The edelweiss post and core system also showed

similar kind of failure mode but post debonding was not seen. The possible

explanation of occurrence of such condition may be due to the monobloc system

achieved in the case of Edelwiess post and core . In the present study twenty samples

were restored with Edelweiss post and core single unit .These samples showed a mean

fracture resistance of 1305.419±327.689 N. The type of fractures seen in Edelweiss

post and core single unit group were 85% core fracture, 15% tooth fracture .No post-

core debonding nor post fractures or root fracture were observed. The results obtained

in the present study showed that the Edelweiss post and core single unit showed

mainly non catastrophic fractures like the Glass fiber post.

Limitations of the study :

According to the study done by Asif et al 1993 , a

complete crown with a 2mm ferrule on the sound tooth structure changed the

distribution of forces to the root and the post and core complex .In this study the test

loads were applied directly on the cores which were not restored with a complete

crown.This was to exclude any external strengthening influence on the post and core

72

foundation. If complete crown over the core were included in the study the results of

this study may have been different.79Another limitation of this study was that

continually increasing static load was applied on the samples which are not the kinds

of load in the oral cavity.A study under cyclic loading would have probably mimicked

forces acting on the teeth in the oral cavity.12Futhermore, this is an invitro study .The

performance of the material might be different in clinical situation.A long term

clinical evaluation of success of these material in restoring the tooth to its natural

strength will help in their comparison.

73

CONCLUSIONS

Within the limitation of the study ,considering the fracture resistance and the failure

mode of the Glass reinforced fiber post with dual cure composite core build up

(CORE X FLOW) and Edelweiss resin composite post and core single unit it can be

concluded that

• The fracture resistance of Edelweiss resin composite post and core single unit

is significantly more than the Glass fiber post .

• Failure modes in both the groups were non catastrophic in nature.

• The failure mode of Glass fiber post was mainly core fracture, post debonding,

post fracture and tooth fracture while Edelweiss resin composite post and core

single unit showed core fractures and tooth fracture. But no post debonding or

post fracture were seen in Edelweiss post and core single unit.

74

SUMMARY

Endodontically treated teeth show a lower fracture resistance to intraoral forces. Post

endodontic tooth fractures usually occur as a result of weakened tooth structure, large

dental caries, tooth wear, and physical changes in tooth structure caused by aging,

vital pulp tissue loss, and endodontic therapy procedures . The fracture susceptibility

of teeth restored with posts may be related to factors such as the amount of remaining

tooth structure, which provides resistance to the fracture of the tooth, as well as the

characteristics of the post, such as the material composition, modulus of elasticity,

diameter and length.

Metallic posts have a much higher modulus of elasticity than

the supporting dentine; this mismatch in modulus could lead to stress concentration and

failure. This has lead to the search for a non metallic fiber based material that has

modulus closer to that of dentine .

Tooth-colour posts have increased in popularity since they

were introduced in 1997. Prefabricated tooth colored post systems have become more

popular because they can provide satisfactory results while saving chair time and redu-

cing costs.

Integration of adhesive technique into post and core procedures

resulted in “monobloc” type of restoration. So in glass fiber post and composite core

system along with resin adhesive cement resulting in “monobloc” type of restoration

which transmits and distributes functional stresses along the tooth root properly. To

overcome this disadvantage of placing a separate core, recently Edelweiss Dentistry,

Austria has introduced prefabricated tooth colored post and composite core with high

dense laser sintered composite material which has modulus of elasticity similar to that

75

of dentin. This post system with core is customizable and is radiopaque with a

shortened chair side time and improved clinical characteristics.

The present study was done to compare the fracture resistance of glass reinforced

fiber post (Tenax fiber post Trans) with separate dual cure composite resin core build

up with single unit Edelweiss post and core .Forty single rooted mandibular

premolars were decoronated to length 2mm above the cementoenamel junction . The

working length was determined, cleaning and shaping was performed by crown down

technique and obturation was completed.

Obturating material was removed up to 9mm. Peeso reamers were used for

glass fiber post and standardised drills recommended by manufacturer was used for

Edelweiss post-core system for preparation of post space so as to have 5 to 6mm of

gutta percha for apical seal. The samples were divided into two groups (n=40). Group

1–Glass fiber post (Tenax fiber post trans)(n=20) Group 2– Edelweiss resin composite

post and core single unit(n=20) . Then the posts were luted using dual cure resin

cement(Core X Flow) and core build up was done for glass fiber post samples with

direct composite(Dual Cure Core X Flow) to same size and shape for fracture

resistance test such that both groups have standardised their core build up of 5.5mm

length and 5mm width. All samples roots were mounted on resin blocks to simulate

periodontal ligament. The models for fracture resistance test were then loaded in

universal loading machine at 135º angulation on the core with a cross head speed

0.5mm/min and tip diameter of 1mm.

The results of fracture resistance test showed that Group 2

(Edelweiss resin composite post and core) showed highest fracture resistance when

compared to Group 1 (Glass fiber post -Tenax fiber post trans ).

76

The failure mode of both the groups were also observed under

stereomicroscope 20X . The failure mode of Glass fiber post showed non catastrophic

core fractures,post debonding,post fracture and tooth fracture while Edelweiss resin

composite post and core single unit also showed non catastrophic core and tooth

fractures.

77

REFERENCES

1. Saritha MK, Paul U, Keswani K, Jhamb A, Mhatre SH, Sahoo PK.

Comparative evaluation of fracture resistance of different post systems.

Journal of International Society of Preventive & Community Dentistry.

2017 Nov;7(6):356.

2. Tikku AP, Chandra A, Bharti R. Are full cast crowns mandatory after

endodontic treatment in posterior teeth?. Journal of conservative dentistry:

JCD. 2010 Oct;13(4):246.

3. Makade CS, Meshram GK, Warhadpande M, Patil PG. A comparative

evaluation of fracture resistance of endodontically treated teeth restored

with different post core systems-an in-vitro study. The journal of advanced

prosthodontics. 2011 Jun 1;3(2):90-5.

4. Moyin S, Chaturvedi S, Alqahtani NM, Shariff M, Abdelmonem AM,

Alfarsi MA. An in vitro evaluation of fracture resistance strength of

different post systems in endodontically treated teeth. Journal of Pharmacy

& Bioallied Sciences. 2019 May;11(Suppl 2):S236.

5. de Farias Sales GC, Gusmão ES, dos Santos RL, Carlo HL, de Barros S,

de Figueiredo VM. Effect of periodontal disease on the bond strength of

fiber post cemented with different adhesive systems and resin luting

agents. Applied Adhesion Science. 2014 Dec;2(1):11.

6. Qualtrough AJ, Mannocci F. Tooth-colored post systems: a review.

Operative Dentistry. 2003 Jan 1;28(1):86-91.

78

7. Trabert KC, Cooney JP. The endodontically treated tooth. Restorative

concepts and techniques. Dental Clinics of North America. 1984

Oct;28(4):923-51.

8. Moosavi H, Afshari S, Manari F. Fracture resistance of endodontically

treated teeth with different direct corono-radicular restoration methods.

Journal of clinical and experimental dentistry. 2017 Mar;9(3):e454.

9. Alhashim NS, Al-Moaleem MM, Al-attas HA. Tooth Colored Post

System: Review of Literature. International Journal of Contemporary

Dentistry. 2013 Mar 8;4(1).

10. Grandini S, Goracci C, Tay F R, Grandini R, Ferrari M: Clinical

evaluation of the use of fiber posts and direct resin restorations for

endodontically treated teeth. International J Prosthet Dent 2005; 18: 399-

404.

11. Peutzfeldt A, Sahafi A, Asmussen E. A survey of failed post-retained

restorations. Clinical oral investigations. 2008 Mar 1;12(1):37.

12. Kulkarni K, Godbole SR, Sathe S, Gotoorkar S, Jaiswal P, Mukherjee P.

Evaluation of the Mode of Failure of Glass Fiber Posts: An In Vitro

Study.International journal of scientific study. 2016 Mar 1;3(12):34-9.

13. Glassman GD, Serota KS. Endoesthetics. Rehabilitation of the

endodontically treated tooth. Dental clinics of North America. 1998

Oct;42(4):799-811.

14. Alnaqbi IO, Elbishari H, Elsubeihi ES. Effect of Fiber Post-Resin Matrix

Composition on Bond Strength of Post-Cement Interface. International

journal of dentistry. 2018;2018.

79

15. Shukri BM. Evaluation the Fracture Resistance of Endodontically Treated

Teeth Restored With Different Post and Core Materials. Tikrit Journal for

Dental Sciences. 2013;2(2):110-6.

16. Mangold JT, Kern M. Influence of glass-fiber posts on the fracture

resistance and failure pattern of endodontically treated premolars with

varying substance loss: an in vitro study. The Journal of prosthetic

dentistry. 2011 Jun 1;105(6):387-93.

17. Rezaei Dastjerdi M, Amirian Chaijan K, Tavanafar S. Fracture resistance

of upper central incisors restored with different posts and cores.

Restorative dentistry & endodontics. 2015 Aug 1;40(3):229-35.

18. Newman MP, Yaman P, Dennison J, Rafter M, Billy E. Fracture resistance

of endodontically treated teeth restored with composite posts. The Journal

of prosthetic dentistry. 2003 Apr 1;89(4):360-7.

19. Torabi K, Fattahi F. Fracture resistance of endodontically treated teeth

restored by different FRC posts: an in vitro study. Indian Journal of Dental

Research. 2009 Jul 1;20(3):282.

20. Sinha S, Jayakumar T, Santhosh L, Panchajanya S, Aswathnarayana S. A

comparative evaluation of the fracture resistance and mode of failure of

GC ever Stick post and Easy post-an in vitro study. International Journal

of Oral Health Dentistry. 2017;3(2):77-80.

21. Scotti N, Rota R, Scansetti M, Migliaretti G, Pasqualini D, Berutti E. Fiber

post adhesion to radicular dentin: The use of acid etching prior to a one-

step self-etching adhesive. Quintessence International. 2012 Jul 1;43(7).

22. Abduljabbar T, Sherfudhin H, AlSaleh SA, Al-Helal AA, Al-Orini SS, Al-

Aql NA. Fracture resistance of three post and core systems in

80

endodontically treated teeth restored with all-ceramic crowns. King Saud

University Journal of Dental Sciences. 2012 Jan 1;3(1):33-8.

23. Amarnath GS, Swetha MU, Muddugangadhar BC, Sonika R, Garg A, Rao

TP. Effect of post material and length on fracture resistance of

endodontically treated premolars: an in-vitro study. Journal of

international oral health: JIOH. 2015 Jul;7(7):22.

24. Torres-Sánchez C, Montoya-Salazar V, Córdoba P, Vélez C, Guzmán-

Duran A, Gutierrez-Pérez JL, Torres-Lagares D. Fracture resistance of

endodontically treated teeth restored with glass fiber reinforced posts and

cast gold post and cores cemented with three cements. The Journal of

prosthetic dentistry. 2013 Aug 1;110(2):127-33.

25. Abdulrazzak SS, Sulaiman E, Atiya BK, Jamaludin M. Effect of ferrule

height and glass fibre post length on fracture resistance and failure mode

of endodontically treated teeth. Australian Endodontic Journal. 2014

Aug;40(2):81-6.

26. Adanir N, Belli S. Evaluation of different post lengths’ effect on fracture

resistance of a glass fiber post system. European journal of dentistry. 2008

Jan;2:23.

27. Suliman RT. Evaluation the Effect of Thermocycling on Push Out Bond

Strength of Fiber Post to Human Radicular Dentin (An In Vitro Study).

Evaluation. 2015 May;4(5).

28. Kathuria A, Kavitha M, Khetarpal S. Ex vivo fracture resistance of

endodontically treated maxillary central incisors restored with fiber-

reinforced composite posts and experimental dentin posts. Journal of

conservative dentistry: JCD. 2011 Oct;14(4):401.

81

29. Kurthukoti AJ, Paul J, Gandhi K, Rao DB. Fracture resistance of

endodontically treated permanent anterior teeth restored with three

different esthetic post systems: An in vitro study. Journal of Indian Society

of Pedodontics and Preventive Dentistry. 2015 Oct 1;33(4):296.

30. Franco ÉB, do Valle AL, de Almeida AL, Rubo JH, Pereira JR. Fracture

resistance of endodontically treated teeth restored with glass fiber posts of

different lengths. The Journal of prosthetic dentistry. 2014 Jan

1;111(1):30-4.

31. Ayna B, Ayna E, Çelenk S, Başaran EG, Yilmaz BD, Tacir İH, Tuncer

MC. Comparison of the clinical efficacy of two different types of post

systems which were restored with composite restorations. World journal of

clinical cases. 2018 Mar 16;6(3):27.

32. Kaur J, Sharma N, Singh H. In vitro evaluation of glass fiber post. Journal

of clinical and experimental dentistry. 2012 Oct;4(4):e204.

33. Mirseifinejad R, Tabrizizade M, Davari A, Mehravar F. Efficacy of

different root canal irrigants on smear layer removal after post space

preparation: a scanning electron microscopy evaluation. Iranian

endodontic journal. 2017;12(2):185.

34. Campos ea, michel md, gonzaga cc. Customized fiber glass posts. Fatigue

and fracture resistance. American journal of dentistry. 2012 Feb;25(1).

35. Padmanabhan P. A comparative evaluation of the fracture resistance of

three different pre-fabricated posts in endodontically treated teeth: An in

vitro study. Journal of conservative dentistry: JCD. 2010 Jul;13(3):124.

36. Schiavetti R, Garcia-Godoy F, Toledano M, Mazzitelli C, Barlattani A,

Ferrari M, Osorio R. Comparison of fracture resistance of bonded glass

82

fiber posts at different lengths. American journal of dentistry. 2010 Aug

1;23(4):227.

37. Salameh Z, Sorrentino R, Papacchini F, Ounsi HF, Tashkandi E, Goracci

C, Ferrari M. Fracture resistance and failure patterns of endodontically

treated mandibular molars restored using resin composite with or without

translucent glass fiber posts. Journal of endodontics. 2006 Aug

1;32(8):752-5.

38. Manjunath P, Sujatha I, Jayalakshmi KB. Comparison of fracture

resistance of endodontically treated teeth restored with two different fiber

posts.

39. Kumar L, Pal B, Pujari P. An assessment of fracture resistance of three

composite resin core build-up materials on three prefabricated non-

metallic posts, cemented in endodontically treated teeth: an in vitro study.

PeerJ. 2015 Feb 24;3:e795.

40. Panitiwat P, Salimee P. Effect of different composite core materials on

fracture resistance of endodontically treated teeth restored with FRC posts.

Journal of Applied Oral Science. 2017 Apr;25(2):203-10.

41. Theodor Y, Koesmaningati H, Gita F. Adhesive capability of total-etch,

self-etch, and self-adhesive systems for fiber post cementation. InJournal

of Physics: Conference Series 2017 Aug (Vol. 884, No. 1, p. 012098). IOP

Publishing.

42. Sadeghi M. A comparison of the fracture resistance of endodontically

treated teeth using three different post systems. Journal of Dentistry of

Tehran University of Medical Sciences. 2006;3(2):69-76.

83

43. Pereira JR, Valle AL, Juvêncio TM, Fernandes TM, Ghizoni JS, Só MV.

Effect of post length on endodontically treated teeth: fracture resistance.

Brazilian journal of oral sciences. Piracicaba. Vol. 9, no. 3 (July/Sept.

2010), p. 371-375. 2010.

44. Ok E, Dilber E, Altunsoy M, Kalkan A, Demir N. Comparison of the

effect of three different post systems on root fracture. Journal of

Restorative Dentistry. 2014 Sep 1;2(3):125.

45. Armstrong S, Breschi L, Özcan M, Pfefferkorn F, Ferrari M, Van

Meerbeek B. Academy of Dental Materials guidance on in vitro testing of

dental composite bonding effectiveness to dentin/enamel using micro-

tensile bond strength (μTBS) approach. Dental Materials. 2017 Feb

1;33(2):133-43.

46. Peroz I, Blankenstein F, Lange KP, Naumann M. Restoring endodontically

treated teeth with posts and cores--a review. Quintessence international.

2005 Oct 1;36(9).

47. Bateman G, Ricketts DN, Saunders WP. Fibre-based post systems: a

review. British dental journal. 2003 Jul;195(1):43.

48. Kallio TT, Lastumäki TM, Vallittu PK. Bonding of restorative and

veneering composite resin to some polymeric composites. Dent Mater.

2001.Jan;17(1):80–6.

49. Vallittu PK.A review of fiber-reinforced denture base resins.J

Prosthodont.1996. Dec;5(4):270–6.

50. Parčina I, Amižić, Baraba A. Esthetic Intracanal Posts. Acta Stomatologica

Croatica. 2016;50(2):143-150.

84

51. Richard Trushkowsky, Fiber Post Selection and Placement Criteria: A

Review, Inside Dentistry, April 2008, Volume 4, Issue 4.

52. Sharma S, Attokaran G, Singh KS, Jerry JJ, Ahmed N, Mitra N.

Comparative evaluation of fracture resistance of glass fiber reinforced,

carbon, and quartz post in endodontically treated teeth: An in-vitro study.

Journal of International Society of Preventive & Community Dentistry.

2016 Jul;6(4):373.

53. Vidhya S, Chandrasekar C, Narayanan L. A comparative evaluation of

fracture resistance and penetration of bonding resin into three different

fiber reinforced posts using confocal microscope. Internet J Dent Sci.

2010;9:1.

54. https://ap.coltene.com/pim/DOC/CAT/doccat60018433-01-19-katalog-

endo-ensenaindv1.pdf

55. Lampl S. Edelweiss dentistry. March 10 2015.http://www. edelweiss-

dentristry.com/en.

56. Singh, I., Shetty, R., Mehta, D., Lampl, S., & Chida, N. (2018).

Prefabricated Laser Sintered Composite Veneers and Occlusal Vertical

Dimensions: Case Reports. The journal of contemporary dental practice,

19 11, 1417-1423 .

57. Stankiewicz NR & Wilson PR (2002) The ferrule effect: literature review

International Endodontic Journal 35(7)575-581.

58. Jotkowitz A & Samet N (2010) Rethinking ferrule—a new approach to an

old dilemma British Dental Journal 209(1) 25 - 33

85

59. Joseph J & Ramachandran G (1990) Fracture resistance of dowel channel

preparations with various dentin thickness Federation of Operative

Dentistry 1(1) 32-35.

60. Fontana PE, Bohrer TC, Wandscher VF, Valandro LF, Limberger IF,

Kaizer OB. Effect of Ferrule Thickness on Fracture Resistance of Teeth

Restored With a Glass Fiber Post or Cast Post. Operative dentistry. 2019

Jul 8.

61. Tjan AH & Whang SB (1985) Resistance to root fracture ofdowel

channels with various thicknesses of buccal dentin walls Journal of

Prosthetic Dentistry 53(4) 496-500.

62. Solano F, Hartwell G, Appelstein C. Comparison of apical leakage

between immediate versus delayed post space preparation using AH Plus

sealer. Journal of endodontics. 2005 Oct 1;31(10):752-4.

63. Goodacre CJ, Spolnik KJ. The prosthodontic management of

endodontically treated teeth: a literature review. Part III. Tooth preparation

considerations. J Prosthodont 1995;4:122–8

64. Sorensen JA, Martinoff JT. Clinically significant factors in dowel design. J

Prosthet Dent 1984;52:28–35.

65. Neagley RL. The effect of dowel preparation on apical seal of

endodontically treated teeth. Oral Surg Oral Med Oral Pathol

1969;28:739–45

66. Hunter AJ, Feiglin B, Williams JF. Effects of post placement on

endodontically treated teeth. J Prosthet Dent 1989;62:166–72

67. Abramovitz L, Lev R, Fuss Z, Metzger Z. The unpredictability of seal after

post space preparation: a fluid transport study. J Endodon 2001;27:292–5

86

68. Heling I, Gorfil C, Slutzky H, Kopolovic K, Zalkind M, Slutzky-Goldberg

I. Endodontic failure caused by inadequate restoration procedures: Review

and treatment recommendations. J Prosthet Dent 2002; 87:674–678.

69. Poletto D, Poletto AC, Cavalaro A, Machado R, Cosme-Silva L, Garbelini

CC, Hoeppner MG. Smear layer removal by different chemical solutions

used with or without ultrasonic activation after post preparation.

Restorative dentistry & endodontics. 2017 Nov;42(4):324-31.

70. Goracci C, Sadek FT, Fabianelli A, Tay FR, Ferrari M. Evaluation of the

adhesion of fiber posts to intraradicular dentin. Oper Dent. 2005 Sep-

Oct;30(5):627-35.

71. Valandro LF, Filho OD, Valera MC, De Araujo MA. The effect of

adhesive systems on the pullout strength of a fiberglass-reinforced

composite post system in bovine teeth. J Adhes Dent. 2005

Winter;7(4):331-6.

72. http://www.dentsply.com.au/www/770/files/dfu-primeandbondnt.pdf

73. Monticelli F, Ferrari M, Toledano M. Cement system and surface

treatment selection for fiber post luting. Medicina Oral Patologia Oral y

Cirugia Bucal. 2008 Mar 1;13(3):214.

74. Bitter K, Meyer-Lückel H, Priehn K, Martus P, Kielbassa AM.

Bondstrengths of resin cements to fiber-reinforced composite posts. Am J

Dent. 2006 Jun;19(3):138-42.

75. Goracci C, Raffaelli O, Monticelli F, Balleri B, Bertelli E, Ferrari M. The

adhesion between prefabricated FRC posts and composite resin cores:

microtensile bond strength with and without post-silanizationDent Mater.

2005 May;21(5):437-44.

87

76. Dietschi D, Ardu S, Rossier-Gerber A, Krejci I. Adaptation of adhesive

post and cores to dentin after in vitro occlusal loading: evaluation of post

material influence. J Adhes Dent. 2006 Dec;8(6):409-19.

77. Ferrari M, Goracci C, Sadek FT, Monticelli F, Tay FR. An investigation of

the interfacial strengths of methacrylate resin-based glass fiber post-core

buildups. J Adhes Dent. 2006 Aug;8(4):239-45

78. https://www.dentsply.de/gebrauchsanweisungen?ifufile=coreXflow_IFU.p

df.

79. Singh V, Bogra P, Gupta S, Kukreja N, Gupta N. Comparative evaluation

of fracture resistance of endodontically treated teeth restored with resin

fiber post and stainless steel post: an in vitro study. Dental Journal of

Advance Studies. 2015 Aug;3(02):080-4.

80. Daivid, Alison JE: Effect of thermocycling on the retention of glass fiber

root canal post, Quntessence Int J, 2003;34:366-369.

81. Xiao J, SanjunZ ,Lina NM: effect of luting cement and thermomechanical

loading on the retention ofglass fiber post in root canal,J of Dent,

2014,42(1):75-83

82. Jakubonytė M, Česaitis K, Junevičius J. Influence of glass fibre post

cementation depth on dental root fracture. Stomatologija. 2018;20(2):43-8.

83. Xible AA, Tavarez RR, Araujo CD, Conti PC, Bonachella WC. Effect of

cyclic loading on fracture strength of endodontically treated teeth restored

with conventional and esthetic posts. Journal of Applied Oral Science.

2006 Aug;14(4):297-303.

84. Shetty N. Types of Post and Core Systems. Journal of International Oral

Health. 2016 Dec 1;8(12):1136.

88

85. Abdelaziz KM, Keshk CK, Al-Mashhour OS, Alhudairy MA, Asiri MS,

Alshehri AM, Elshinawy MI. Fracture resistance of endodontically treated

premolars with optimum and overprepared post spaces. International

Journal of Contemporary Dental & Medical Reviews. 2018;2018.

86. Elshereksi NW, Ghazali M, Muchtar A, Azhari CH. Review of titanate

coupling agents and their application for dental composite fabrication.

Dental materials journal. 2017 Jul 28:2016-014.

87. Anusavice KJ. In: Phillips' Science of Dental Materials. 10th ed.

Philadelphia: WB Saunders Co.; 1996. Mechanical Properties of Dental

Materials (Chapter 4); pp. 49-74

88. Goodacre CJ, Spolnik KJ. The prosthodontic management of

endodontically treated teeth: A literature review. Part I. Success and failure

data, treatment concepts. J Prosthodont 1994;3:243-50.

89. Mehta SB, Millar BJ. A comparison of the survival of fi bre posts

cemented with two different composite resin systems. Br Dent J

2008;205:E23.

90. Bitter K, Kielbassa AM. Post-endodontic restorations with adhesively

luted fiber-reinforced composite post systems: a review. American Journal

of Dentistry. 2007 Dec 1;20(6):353.

91. Beltagy TM. Fracture resistance of rehabilitated flared root canals with

anatomically adjustable fiber post. Tanta Dental Journal. 2017 Apr

1;14(2):96.

92. Fernandes AS, Dessai GS. Factors affecting the fracture resistance of post-

core reconstructed teeth: a review. International Journal of Prosthodontics.

2001 Jul 1;14(4).

It is an invitro study , hence consent form is not applicable.

Scanned by CamScanner

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Since it is an in -vitro study ,proforma is not applicable.

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ANNEXURE

SAMPLES USED FOR THE STUDY

FIG 1-20 TEETH SAMPLES -MANDIBULAR PREMOLARS

FIG 2-INDIVIDUAL TOOTH SAMPLE

95

FIG 3-STORAGE 0.5% CHLORAMINE T

FIG 4-MARKING AT 2 MM ABOVE THE LEVEL OF CEMENTO ENAMEL

JUNCTION FOR SECTIONING

96

FIG 5-MEASURING AT 2 MM ABOVE CEMENTO ENAMEL JUNCTION

WITH VERNIER CALIPER

DECORONATION OF THE TOOTH

FIG 6-SECTIONING WITH DIAMOND DISC

97

FIG 7- DECORONATED SAMPLES

FIG 8- ROOT LENGTH STANDARIZED TO APPROX. 13MM

98

ARMAMENTARIUM

FIG-9 SECTIONING AND TOOTH PREPARATION

FIG -10 BIOMECHANICAL PREPARATION

99

FIG 11-OBTURATION

FIG 12-ARMAMENTARIUM FOR POST SPACE PREPARATION –

POST DRILL FOR EDELWEISS POST AND CORE

POST DRILL 9 MM LENGTH

APICAL DIAMETER 1.4MM

100

FIG 13- ARMAMENTARIUM FOR POST SPACE AND CEMENTATION OF

THE POST

FIG 14-TENAX FIBER POST

101

FIG-15 EDELWEISS POST & CORE

EDELWEISS MANDIBULAR PREMOLAR POST

LENGTH OF THE POST-9MM

INCISOCERVICAL LENGTH OF THE CORE-5.5MM

MESIODISTAL WIDTH OF THE CORE -5MM

METHODOLOGY

FIG 16-WORKING LENGTH

102

FIG 17- IRRIGATION OF THE ROOTCANAL

FIG 18- BIOMECHANICAL PREPARATION UPTO SIZE F3(30/.09)

103

FIG 19- POST OBTURATION RADIOGRAPH

FIG 20-POST SPACE PREPARATION

FIG 21- RADIOGRAPHIC IMAGE OF THE POST SPACE PREPARATION

104

FIG 22- IRRIGATION OF THE POST SPACE PREPARATION WITH

17%EDTA &NaOCl

FIG 23- CHECKING THE FIT OF THE GLASS FIBER POST

105

FIG 24-CHECKING THE FIT POST OF EDELWEISS POST AND CORE

FIG -25 RADIOGRAPHIC IMAGE OF FIT OF GLASS FIBER POST

FIG -26 RADIOGRAPHIC IMAGE OF THE FIT OF EDELWEISS POST

106

CEMENTATION OF THE POST SYSTEMS

FIG 27-ETCHING WITH 36% PHOSPHORIC ACID

FIG-28 REMOVAL OF REMAINING ETCHANT AND DRYING OF THE

POST SPACE WITH PAPER POINTS

107

FIG 29- APPLICATION OF THE BONDING AGENT

FIG 30- APLLICATION OF THE BONDING AGENT IN THE POST SPACE

108

FIG 31- REMOVAL OF EXCESS /POOLING OF BONDING AGENT IN THE

POST SPACE

FIG 32- CURING OF THE BONDING AGENT WITH LIGHT CURING UNIT

( ULTRADENT VALO)

109

FIG 33- APPLICATION OF SILANE COUPLING AGENT ON GLASS FIBER

POST

FIG 34-APPLICATION OF EDELWEISS VENEER BOND ON EDELWEISS

POST &CORE

110

FIG 35- INJECTING DUAL CURE CORE X FLOW INTO THE POST

SPACE FOR CEMENTATION

FIG 36- CEMENTATION OF EDELWEISS POST AND CORE

111

FIG 37 -TOOTH SAMPLE AFTER CEMENTATION OF EDELWEISS POST

AND CORE

FIG 38-CEMENTATION OF GLASS FIBER POST

112

FIG 39- CORE BUILD UP FOR GLASS FIBER POST WITH DUAL CURE

CORE X FLOW

FIG 40- RADIOGRAPHIC IMAGE OF GLASS FIBER POST WITH DUAL

CURE CORE X FLOW

113

FIG 41-CORE BUILD UP STANDARIZED TO LENGTH 5.5MM AND

WIDTH 5MM

FIG 42-TOTAL SAMPLES AFTER CEMENTATION OF THE TWO POST

SYSTEMS

114

FIG 43- MOUNTING OF THE SAMPLES IN THE ACRYLIC BLOCK WITH

SIMULATION OF PERIODONTAL LIGAMENT

FIG 44 - THERMOCYCLING OF THE TOOTH SAMPLES

115

Fig 45 -FRACTURE TESTING -UNIVERSAL TESTING MACHINE

FIG 46-SCREEN SHOT OF FRACTURE RESISTANCE OF EDELWEISS

POST AND CORE

116

FIG 47- SCREEN SHOT OF FRACTURE RESISTANCE OF GLASS FIBE

FIG 48- FAILURE PATTERN VIEWED UNDER STEREOMICROSCOPE

117

FIG 49- TYPES OF FAILURE VIEWED UNDER

STEREOMICROSCOPE

GLASS FIBER POST

118

EDELWEISS POST AND CORE SINGLE UNIT

119