dr. ratnakar. p - 52.172.27.147:8080

“ Comparison of different endodontic file systems on the incidence of root

dentinal defects with and without EDTA – A stereomicroscopic analysis”

By

Dr. T. NANDA KUMAR

Dissertation Submitted to the Rajiv Gandhi University of Health Sciences In partial fulfillment of the requirements

For the award of degree of

MASTER OF DENTAL SURGERY

IN

CONSERVATIVE DENTISTRY AND ENDODONTICS

Under the guidance of

Dr. RATNAKAR. P M.D.S

Professor& HOD Department of conservative dentistry and endodontics

DEPARTMENT OF CONSERVATIVE DENTISTRY AND ENDODONTIC S H.K.E. SOCIETY’S S. NIJALINGAPPA INSTITUTE OF DENTA L SCIENCES

AND RESEARCH, KALABURAGI, KARNATAKA. 2016-19

XI

List Of Abbreviations

%: Percentage

VRF: Vertical root fracutre

R:phase :rhombohedral phase

NiTi: Nitinol or Nickle Titanium

PTN:protaper next

SAF: self adjusting file

TF: Twisted File

EDTA: Ethylene Diamine Tetraacetic Acid

Naocl: sodium hypochlorite#

mm: Millimeter

cm:centimeter

#: number

rpm: revolutions per minute

P: probability value

N-cm: Newton - centimeter

TFA: Twisted File Adaptive

WOG: Wave One Gold

CM: Controlled Memory

XII

LIST OF TABLES

Table

No.

Title Page

No.

1 Types of root dentinal cracks 32

2 The percentage and number of root dentinal defects at different root level as a

result of root canal instrumentation in all groups.

44

3 Comparison of types of root dentinal defects between the all groups as a result of

root canal instrumentation in sub group with EDTA gel

46

4 Comparison of types of root dentinal defects between the all groups as a result of

root canal instrumentation of sub group without EDTA gel.

48

5 Comparison of root dentinal defect as a result of root canal instrumentation

between the sub groups within the group.

50

6 Comparison of root dentinal defect as a result of root canal instrumentation

between the groups.

51

XIII

LIST OF FIGURES

Figure

No.

Title Page

No.

1 Specimens 33

2 Specimens mounted in epoxy resin blocks (2X2X2cm) 33

3 Coronal sectioning 34

4 Standardisation of root length 34

5 Decoronated sectioned sample 34

6 Samples divided in to groups 35

7 Armamentarium 35

8 Hand k file group 36

9 Twisted fIle group 36

10 Protaper Next File group 37

11 Self Adjusting file group 37

12 Cleaning and shaping of specimens with Hand K file,Twisted Adaptive file,

Self Adjusting File and Protaper Next file

38

13 Isomet saw low speed saw Buehler 38

XIV

14 Sectioned sample of 9mm,6mm,3mm 39

15 Digital stereomicroscope 39

16 Stereomicroscopic images showing No defects at 3mm,6mm,9mm 40

17 Stereomicroscopic images showing Type I defects at 3mm,6mm,9mm 41

18 Stereomicroscopic images showing Type II defects at 3mm,6mm,9mm 42

19 The percentage and number of root dentinal defects at different root level as a

result of root canal instrumentation in all groups

45

20 Multiple bar diagram represents comparison of types of root dentinal defects

between the all groups as a result of root canal instrumentation of sub group

with EDTA

47

21 Multiple bar diagram represents comparison of types of root dentinal defects

between the all groups as a result of root canal instrumentation of sub group

without EDTA

49

ABSTRACT

TITLE:Comparison of different endodontic file systems on the incidence of root dentinal

defects with and with EDTA – A stereomicroscopic analysis.

Aims and objectives:The aim of this study was to evaluate the incidence of root dentinal

defects while using Hand k-file, Twisted File,Self adjusting file, protaper next file with

and without ethylenediaminetetraacetic acid (EDTA) gel.

Material and methods:Hundred extracted mandibular first premolars were included.

The teeth were decoronated until roots of 12± 1 mm were obtained. Samples were

distributed into five groups further each group divided in to subgroups.Subgroup 1a: hand

k file + EDTA, subgroup1b: hand k file; subgroup: 2aTwisted File + EDTA, subgroup2b:

Twisted File; subgroup3a: Self adjusting file+ EDTA, subgroup3b:Self adjusting file;

subgroup4a: Protaper next file+ EDTA, subgroup4b: Protaper next file; subgroup5a: no

canal preparation (control) + EDTA, subgroup5b: no canal preparation (control). Roots

were horizontally sectioned from 3, 6 and 9 mm from the apex and observed under

stereomicroscope.

Results:The number and the incidence of cracks were recorded and statistically analyzed

withFischer’s exact test. Control group did not reveal any cracks. root dentinal defect as a

result of root canal instrumentation in all groups. Group 4(PTN) showed more no.of

defects in both the subgroups that is 43.3% (with EDTA) and 33.3% (without EDTA)

while Group 3 showed less no.of defects that is 10% (with EDTA) and 6.7% (without

EDTA) with p value <0.01 as significant.

Conclusion:The incidence of root dentinal defects after root canal preparation with

different endodontic file system with EDTA was comparatively more than without

EDTA.The no. of root dentinal defects were highest with Protaper next group then

followed by twisted file group. Comparatively very less no.of root dentinal defects were

observed in Self-adjusting file group and Hand K-file group.

Keywords: Root dentinal defects, EDTA, Hand K-file, Twisted file, Self adjusting file,

Protaper next.

1

INTRODUCTION

Endodontic therapy involves treating vital and necrotic dental pulps so that patients can retain

their natural teeth in function and esthetics. Although successful therapy depends on many

factors, one of the most important steps in any root canal treatment is canal preparation. This is

essential because preparation determines the efficacy of all subsequent procedures and includes

mechanical debridement, creation of space for medicament delivery, and optimized canal

geometries for adequate obturation. Unfortunately, canal preparation influenced adversely by the

highly variable root-canal anatomy and the relative inability of the operator to visualize this

anatomy from radiographs. Hence, root canal preparation is not only important but also

demanding for the clinician1.

Mao Tse Tung wrote “The foundation of success is failure”. Clinicians who strive for endodontic

excellence appreciate the elements that comprise success and use these criteria to evaluate the

causes of failure. Endodontic failures may generate confusion, anxiety, and frustration for

clinicians and patients alike. Focusing the attention of the patient on the stepping stones to

endodontic health helps alleviate concerns and creates the clinical pathway to successful

retreatment. Regretfully, numerous additional failures can be identified as cases treated with

techniques incongruent with biological principles. Regardless, the causes of failure are

multifaceted and endure due to an abundance of misinformation, misconceptions, and

perpetuated endodontic myths.

Additionally, spectacular change is occurring in clinical endodontics and is driven by an

explosion of new technologies, instruments, materials, and the emergence of new practice

building techniques.

2

It was found that endodontic success rates ranging from 53% to 95%. This startling range in

success can be attributable to a variety of factors such as number of treated cases, tooth type,

operator ability, limited follow-up periods, and all the clinical treatment factors that will

ultimately influence success or failure. Even if we assume 90% of all endodontics works over

time, the reciprocal failure rate is 10%. Clinical observation of endodontic failure reveals

multiple etiologies.

The causes of endodontic failure include coronal leakage, radicular fractures, post errors due to

diameter, length and direction, missed canals, short fills, overextensions with internal

underfilling, blocks, ledges, perforations, transportations, broken instruments, surgical failures,

and hopelessly involved periodontal teeth2.

Shemesh ,Bier et al. were possibly the first authors to report that root canal preparation with

rotary files may cause dentinal damage. They reported that canal preparation could cause

significant dentinal defects such as fractures, craze lines, and incomplete cracks. Vertical root

fracture (VRF) is likely caused by the propagation of a given initial dentinal defect, such as a

microcrack or craze lines. Wilcox et al., observed that all teeth that they evaluated showed some

degree of craze lines, and this led to the rationale that VRF is the endpoint of these dentinal

defects when the tooth is exposed to continual stress from any source3.

Traditionally, canal shaping has been achieved using (international organization for

standardization) ISO-normed 0.02 tapered stainless steel instruments manipulated by hand. The

preparation sequence advocated originally for traditional hand instruments involved determining

working length radiographically followed by preparation of the canal from the apical constriction

to the orifice. Unfortunately, when carried out in curved canals such procedure, often results in

iatrogenic damage to the natural shape of the canal, particularly in its apical third. A further

3

disadvantage of 0.02 taper hand instruments is their tendency to create narrow canal shapes

minimizing access of irrigants and creating potential to allow debris to be pushed apically4.

In 2008, Sybron Endo presented twisted file the first fluted Ni-Ti file manufactured by plastic

deformation, similar to the twisting process that is used to produce stainless steel K-files.

According to the manufacturer, a thermal process allows twisting during a phase transformation

into the so-called (rohmbohedral) R-phase of NiTi. The instrument is available with only no. 25

tip sizes, in taper .04% up to .12%. However, instruments with tip sizes no. 30, 35, and 40 were

recently added. The unique production process is believed to result in superior physical

properties; indeed, early studies suggested significantly better fatigue resistance of size no. 25

.06 taper5.

ProTaper Next (PTN)(DentsplyMaillefer, Ballaigues, Switzerland) is a novel NiTi file system. It

has an off-centered rectangular design and progressive and regressive percentage tapers on a

single file. Having various percentage tapers decreases the effect of the screw and dangerous

taper lock by minimizing the contact between the file and the dentin. Moreover, the offset design

maximizes augering debris out of the canal compared with a file with a centered mass and axis of

rotation6.

All rotary file systems tested so far create micro-cracks in the radicular dentin in a high

percentage of treated roots, which may predispose them to vertical root fractures. This last

challenge applies to roots with round crosssections as well .The new Self-adjusting File (SAF)

technology uses a hollow, compressible NiTi file, with no central metal core, through which a

continuous flow of irrigant is provided throughout the procedure. The SAF technology allows for

effective cleaning of all root canals including oval canals, thus allowing for the effective

disinfection and obturation of all canal morphologies.

4

1. This technology uses a new concept of cleaning and shaping in which a uniform layer of

dentin is removed from around the entire perimeter of the root canal, thus avoiding

unnecessary excessive removal of sound dentin. Furthermore, the mode of action used by

this file system does not apply all root canals to a circular bore, as do all other rotary file

systems, and does not cause micro-cracks in the remaining root dentin7.

Hence, the present study have been undertook to evaluate and compare the incidence of dentinal

microcracks caused by hand and rotary NiTi (twisted file and ProTaper Next file) and Self

Adjusting File during root canal preparation with and without using EDTA(ethylene

diaminetetraacetic acid ).

5

Aims and objectives

Aim of the study: Evaluation of incidence of root dentin micro cracks after root canal

preparation with different endodontic file system with and without use of EDTA.

Objectives of the study:

1. Root canal instrumentation was done with and without use of EDTA and dentinal cracks

were assessed at 9mm, 6mm, 3mm of root length.

2. Comparing the type of dentinal cracks formed in root duringroot canal instrumentation

using different file systems.

6

REVIEW OF LITERATURE

Lisa R. Wilcox, Chad Roskelley, and Todd Sutton (1997) conducted an invitro study to assess

the effect of lateral condensation forces on the development of vertical root fracture (VRF) in

teeth after controlled internal root reduction. Thirty four maxillary anterior teeth were prepared

with the step-back method so that the canal width was 20% of the total root width and obturated.

24 hours after obturation, the teeth were examined by transillumination for VRF. Teeth not

exhibiting VRF were tested after Guttapercha removal and further canal enlargement to 30%,

40%, and 50% of the root width. The teeth sectioned to examine under stereomicroscope. No

VRF occurred at 20% or 30%; five teeth fractured at 40% and seven at 50%. Craze lines

developed in all seventeen of the remaining unfractured samples. 8

Adorno CG, T. Yoshioka and H. Suda (2010) evaluated the effects of working length and root

canal preparation technique on crack development in the apical root canal wall. Seventy

mandibular premolars mounted in a resin block with simulated periodontal ligaments. The crown

was removed 2 mm above the proximal cementoenamel junction to ensure straight line access

and provide a reference point. The apical 2-3 mm of the root exposed to allow intraoperative

image recording. The teeth were randomly divided into seven experimental groups (n=10)

according to preparation technique and working length: Group A, step back preparation with

stainless steel files with working length set at the apical foramen and defined as root canal

length(CL); group B, same as for A, except that the working length was CL-1mm; group C,

crown down preparation with Profile instruments followed by an apical enlargement sequence

with CL as working length and group D, same as for C, except that the working length was CL-

1mm. Groups E, F and G served as controls. Groups E and F were prepared only with the crown

down sequence up to CL and CL-1mm, without further apical enlargement, and Group G was

7

left unprepared. Digital images of the apical root surface (AS) were recorded before preparation,

immediately after instrumentation and after removing the apical 1mm (AS-1mm) and 2mm (AS-

2mm) of the root end. It was observed that working length significantly affected crack

development at AS (p < 0.05). Preparation technique significantly affected crack development at

AS-1mm (p < 0.05).At AS-2mm; there was no significant difference between preparation

technique and working length in terms of crack development on dentin wall. It was concluded

that root canal preparation alone, regardless of the technique used, can potentially generate

cracks on the apical root canal wall as well as apical surface. Working 1 mm short of the apical

foramen might produce fewer cracks in the apical region. 9

Oguz Yoldas, Shehnaz Yilmaz, Ghokam Atakan, CihanKuden and Zeynep Kasan (2012)

conducted an invitro study to compare dentinal microcrack formation while using hand files, four

brands of nickel-titanium (NiTi) rotary files and the self-adjusting file in mesial canals of

mandibular molars. One hundred forty mandibular first molars were selected. Twenty teeth were

left unprepared and served as control, and the remaining one hundred twenty teeth were

randomly divided into six groups: Hand files (DentsplyMaillefer), HERO Shaper (Micro-Mega),

Revo-S (Micro-Mega), Twisted file (Sybron Endo), ProTaper (DentsplyMaillefer), and Self-

adjusting files (ReDent Nova). After canal instrumentation, roots were sectioned at 3mm, 6mm

and 9 mm from the apex and observed under a stereomicroscope for the presence of dentinal

microcracks. Results revealed that the control, hand file and self-adjusting file groups did not

show any microcracks. In roots prepared with the HERO Shaper, Revo S, Twisted file and

ProTaper, dentinal microcracks were observed in 60%, 25%, 44% and 30% of teeth respectively.

There was a significant difference between the control/ hand file/ self-adjusting file group and

the four NiTi rotary instrument groups (p < 0.0001). However, no significant difference was

8

found among the four NiTi rotary instruments (p > 0.005). It was concluded that all rotary files

created microcracks in the root dentin, whereas the self-adjusting file and hand instrumentation

presented with satisfactory results with no dentinal microcracks. 10

An invitro study was undertaken by Rui Liu, Ben Xiang Hou, Paul R. Wesselink , Min-Kai

Wu, and Hagay Shemesh (2013) to compare the incidence of root cracks observed at the apical

root surface and in the canal wall after canal instrumentation with three single-file systems and

the ProTaper system. One hundred mandibular incisors were selected. Twenty control teeth are

coronally flared with Gates-Glidden drills and no further preparation was made. The other 80

teeth were mounted in resin blocks with simulated periodontal ligaments and the apex was

exposed. They were divided into 4 experimental groups(n = 20); the root canals were first

coronally flared with Gates-Glidden drills and then instrumented to the full working length with

the ProTaper (DentsplyMaillefer), OneShape (Micro-Mega), Reciproc (VDW) and the Self-

Adjusting File (ReDent Nova). The apical root surface and horizontal sections 2, 4, and 6 mm

from the apex were observed under a microscope to evaluate for the presence of cracks. No

cracks were found in the control teeth and teeth instrumented with Self adjusting file, whereas

cracks were found in 50%, 35% and 5% of the teeth after canal instrumentation with the

ProTaper, One Shape and Reciproc files respectively. The difference between the experimental

groups was statistically significant (p < 0.001). The authors concluded that the Self-adjusting file

and Reciproc files caused less cracks compared to the ProTaper and OneShape file. 11

Ellemieke S. Hin, Min-Kai Wu, Paul R. Wesselink, and Hagay Shemesh In (2013) evaluated

the incidence of microcracks in root dentin after root canal shaping with hand files,SAF,

ProTaper and Mtwo. One hundread extracted tooth were selected and kept in distilled water.

They were divided into five groups of twenty each, group-1 no root canal preparation performed.

9

Group -2 was prepared with K-Flexofiles.Group-3 prepared with ProTaper file. Group 4 was

prepared with Mtwo. Group -5 was prepared by SAF. Roots were sectioned horizontally at 3, 6,

and 9 mm from apex and observed under microscope. From the study it has been noticed that

hand files did not produced any cracks, SAF produced incomplete cracks where as ProTaper and

Mtwo produced complete cracks. 12

N. Tulasi Priya Veeramachaneni Chandrasekhar, S.Anita, Muralidhar Tummala,

T.B.Phanindar Raj, Vijetha Badami, Pradeep Kumar, E.Soujanya (2014) compared the

incidence of dentinal microcracks after instrumentation with various types of NiTi files in rotary

and reciprocating motion. One hundred human extracted mandibular central incisors were taken

and divided into 10 groups (n=10);Group 1- No preparation (Positive Control group), Group 2 –

Hand instrumentation with NiTi K-files (Negative Control group), Groups 3,4 - ProTaper files

(DentsplyMaillefer) in rotary and reciprocating motion respectively, Groups 5,6 - ProTaper Next

files (DentsplyMaillefer) in rotary and reciprocating motion respectively, Groups 7,8 – Oneshape

files (Micro-Mega) in rotary and reciprocating motion respectively, Groups 9,10 – Reciproc files

(VDW) in rotary and reciprocating motion respectively. Specimens were sectioned horizontally

at 3, 6 and 9 mm from the apex and dentinal micro cracks were observed under a

stereomicroscope. No cracks were observed in the controls, whereas all other instrumentation

protocols resulted in dentinal microcracks. Least cracks were seen in canals instrumented with

ProTaper Next files both in rotary and reciprocating motion. Full sequence rotary systems

showed less cracks than single file systems and full sequence rotary systems showed less cracks

in reciprocating motion than in rotary motion. 13

Ersan CE Iceek, Mustafa Murat Koceak, Baran Can Sage Lam, And Sibel Koceak (2014)

evaluated the formation of microcracks in root canals after instrumentation with different NiTi

10

rotary file systems. Sixty extracted mandibular molars were selected. The mesial roots were

resected and teeth were randomly divided into four groups (n=15). Group 1 samples were

prepared with K- Flexofiles (Dentsply-Maillefer), group 2 with ProTaper Universal

(DentsplyMaillefer), group 3 with ProTaper Next (DentsplyMaillefer) and group 4 with

WaveOne reciprocating system (DentsplyMaillefer). The roots were then sectioned horizontally

at 3mm, 6mm and 9mm from the apex and digital images were captured at 40 fold magnification

using scanning electron microscopy to detect microcracks. It was observed that the prevalence of

microcracks in group2, group 3 and group 4 were significantly higher when compared to group 1

(p < 0.001). Group 2, group 3 and group 4 demonstrated similar prevalence of microcracks

without significant difference (p > 0.05) in all sections. Also the highest percentage of

microcrack was recorded in 3mm section for all the groups. 14

Ismail Davut Capar, Hakan Arslan, Merve Akcay, and Banu Uysal (2014) investigated the

incidence of cracks in root dentin after root canal preparation with ProTaper Next, Hyflex and

ProTaper universal rotary instruments. One-hundred mandibular premolars were selected.

Twenty-five teeth were left unprepared and served as negative control; another 25 teeth were

instrumented with the ProTaper Universal system (DentsplyMaillefer) up to size F4 as positive

control, and the remaining 50 teeth were shaped with the following experimental groups with an

apical size 40 file: ProTaper Next X4 (DentsplyMaillefer) and HyFlex40/0.4 (VDW), with 25

teeth in each experimental group. After root canal preparation, all of the roots were sectioned

horizontally at 2, 4, 6 and 8 mm from the apex, and the sections were then observed under a

stereomicroscope. No cracks were observed in the negative control group. The ProTaper Next

and Hyflex instruments caused fewer cracks (28%) than the ProTaper Universal instrument

(56%) and the difference was statistically significant (p < 0.05). However, there were no

11

significant differences in crack formation between the ProTaper Next and Hyflex groups (p >

0.05). The authors concluded that all of the instrumentation systems created cracks in root

dentin. However, the ProTaper Next and Hyflex instruments caused fewer dentinal cracks

compared with the ProTaper Universal instrument.15

Ugur Aydin, Fatih Aksoy,Emrah Karatasliogluand, Cihan Yildirim, (2014) evaluated the

incidence of crack formation while using Reciproc (VDW), WaveOne (DentsplyMaillefer) and

Twisted File Adaptive (Kerr Dental) with and without ethylenediaminetetraacetic acid (EDTA).

Seventy extracted mandibular premolars were included in the study. The teeth were decoronated

until roots of 16 mm were obtained. Samples were distributed into seven groups (n=10): group 1,

no canal preparation (control); group 2, Reciproc;group 3, Reciproc + EDTA; group 4,

WaveOne; group 5, WaveOne + EDTA; group 6, Twisted File Adaptive; group 7, Twisted File

Adaptive + EDTA. After instrumentation, roots were horizontally sectioned 3, 6 and 9 mm from

the apex and observed under stereomicroscope. The authors concluded that no microcracks were

observed in the control group, whereas, all other NiTi instruments resulted in dentinal defects.

However, there was no significant difference in crack formation between the experimental

groups. Also, EDTA gel did not reduce the incidence of crack occurrence.16

Gustavo De-Deus, Emmanuel Joao Nogueira Leal Silva, Juliana Marins, Erick Souza,

Aline de Almeida Neves, Felipe Gonc¸alves Belladonna, Haimon Alves, Ricardo Tadeu

Lopes, and Marco Aurelio Versiani (2015) conducted a study to evaluate the frequency of

dentinal microcracks observed after root canal preparation with ProTaper Next (PTN; Dentsply

Maillefer, Ballaigues, Switzerland) and Twisted File Adaptive (TFA; SybronEndo, Orange, CA)

systems through micro–computed tomographic analysis. Twenty moderately curved mesial roots

of mandibular molars presenting a type II Vertucci canal configuration were randomly assigned

12

to 2 experimental groups (n = 10) according to the system used for the root canal preparation:

PTN or TFA systems. The specimens were scanned through high-resolution micro–computed

tomographic imaging before and after root canal preparation. Afterward, pre- and postoperative

cross-sectional images of the mesial roots (N = 25,820) were screened to identify the presence of

dentinal defects. Dentinal microcracks were observed in 38.72% (n = 5150) and 30.27% (n =

3790) of the cross-sectional images in the PTN and TFA groups, respectively. All dentinal

defects identified in the postoperative scans were already present in the corresponding

preoperative images. Concluded that Root canal preparation with PTN and TFA systems did not

induce the formation of new dentinal microcracks.17

Yakup Ustun, Tugrul Aslan, Burak Sagsen, Bertan Kesim(2015) investigated the effects of

different NiTi instruments on dentinal microcrack formation during root canal preparation. 120

extracted human mandibular incisor teeth were divided into five experimental groups and one

control group (n = 20): Group 1: Hand preparation with balanced force technique up to #25 K-

file. Group 2: Preparation with only ProTaper F2 (DentsplyMaillefer) instrument in a

reciprocating movement. Group 3: Preparation of root canals with Reciproc R25 (VDW)

instrument in reciprocating movement. Group 4: Preparation of root canals with ProTaper

instruments up to F2 instrument in rotational movement. Group 5: Preparation with ProTaper

Next (DentsplyMaillefer) instruments up to X2 instrument in rotational movement. No procedure

was applied to the control group. The roots were sectioned horizontally at 3, 6 and 9 mm from

the apex and examined under stereomicroscope for the absence or presence of dentinal

microcracks. The authors concluded that except the hand file and control group, all experimental

groups showed microcrack formation. However, there was no statistically significant difference

amongst the experimental groups regarding the incidence of microcrack formation.18

13

Dilek Helvacioglu Yigit, Seda Aydemir & Ayca Yilmaz (2015) evaluated the presence of

dentinal defects after root canal preparation with hand instruments and two different

reciprocating instruments. Sixty freshly extracted mandibular incisor teeth were selected for the

in vitro study. On the basis of root length, mesiodistal and buccolingual dimensions, the teeth

were allocated into three experimental groups and one control group (n =15). The teeth in the

control group (Group A) were left unprepared. In group B, teeth were prepared with stainless

steel K-files (Mani). In groups C and D, canals were prepared with WaveOne primary

(DentsplyMaillefer) and Reciproc R25 (VDW) instruments, respectively. Horizontal sections

were made 3, 6 and 9 mm from the apex. Samples were stained with methylene blue and viewed

through a stereomicroscope for the detection of microcracks. It was concluded that no defects

were observed in the control group and hand file group. Other than these, all other experimental

groups induced dentinal microcracks, with no significant difference between them. It was also

observed that significantly more defects were demonstrated at 3 mm level in comparison to the

control (p =0.032), whereas, at the other levels, there was no significant difference between the

groups.19

Ertugrul Karatas¸, Hicran Ates¸ Gunduz, Damla Ozsu Kırcı,Hakan Arslan, , Meltem

Colak Topcu, and Kubra Yesildal Yeter (2015) conducted an in vitro study to compare the

incidence of root cracks after root canal instrumentation with the Twisted File Adaptive (Kerr

Dental), WaveOne (DentsplyMaillefer), ProTaper Next ( DentsplyMaillefer) andProTaper

Universal (DentsplyMaillefer) system. Seventy five extracted mandibular central incisors with

mature apices and straight root canals were selected for the study. The teeth were randomly

assigned to one control group and four experimental groups (n=15). In control group, teeth were

not instrumented. Root canals in other groups were instrumented by using the

14

ProTaperUniversal, ProTaper Next, WaveOne, and TF Adaptive systems. All the roots were then

horizontally sectioned 3, 6, and 9 mm from the apex with a low-speed saw under water cooling.

The slices were then viewed through astereomicroscope at x 25 magnification. The samples were

photographed with a camera to determine the presence of dentinal cracks. It was concluded that

except for the control group, all experimental groups resulted in microcrack formation, and the

difference between the control group and the experimental groups was statistically significant (p

< 0.001). Also, the ProTaper Next and TF Adaptive systems produced significantly less cracks

than the ProTaper Universal and WaveOne systems in the apical section (p < 0.05).20

Shu-hui Li, Ying Lu, Dongzhe Song, Xuedong Zhou, mQing-hua Zheng, Yuan Gao, and

Ding-ming Huang (2015) evaluated the occurrence of dentinal microcracks in severely curved

root canals with ProTaper Universal, WaveOne, and ProTaper Next file systems. Sixty extracted

human molars with 25° to 40° root curvatures were divided into 3 groups of 20 canals each

(n=20). ProTaper Universal (DentsplyMaillefer), WaveOne (DentsplyMaillefer), and ProTaper

Next (DentsplyMaillefer ) file systems were used for root canal procedures. Untreated root

canals of 60 molars served as negative controls. After preparation, all roots were stained with 1%

methylene blue for 24 hours. Roots were then sectioned at the most curved plane and 2 mm

below and above the most curved plane with a lowspeed saw under cold water. A

stereomicroscope was used to inspect dentinal microcracks at 60 x magnification. It was

observed that the ProTaper Next system induced less complete and incomplete dentinal

microcracks compared with the ProTaper Universal and WaveOne systems (p < 0.05), and there

were no significant differences between ProTaper Universal and WaveOne systems (p > 0.05).

Thus, the authors concluded that The ProTaper Next system induced less dentinal microcracks

15

during root canal procedures in severely curved root canals as compared with the ProTaper

Universal and WaveOne systems.21

Mohamed Abdel Aziz Mohamed El Sayed, Maryam Omar Al amoud, Malak Rashid

Mgharfaoui (2015) compared the incidence of dentinal defects after using EDTA gel during

root canal preparations by three different instrumentation techniques. One hundred and forty

maxillary central incisors were decoronated and roots were embedded in resin blocks. Twenty

samples were left unprepared (Control group), and the remaining 120 samples were divided into

three groups (n=40). Each group was divided equally into two subgroups (n=20) according to the

use of EDTA gel during root canal instrumentation. Roots were prepared with stainless steel K-

files (Group 1), ProTaper Universal (DentsplyMaillefer) (Group 2) and WaveOne

(DentsplyMaillefer) (Group 3). Roots were then sectioned 3, 6, and 9 mm from the apex, and the

cut surface was observed microscopically and the presence of dentinal defects was checked. It

was observed that unprepared roots did not show any dentinal defects. Dentinal defects were

seen in all experimental groups and the difference between experimental groups and subgroups

regarding the incidence of dentinal defects was not statistically significant. The authors

concluded that canal preparation using hand or rotary files created radicular dentinal defects. The

use of EDTA gel during root canal preparation did not reduce the incidence of dentinal defects.22

Deepa Deepak Shori, Pratima Ramakrishna Shenoi, Arshia R Baig, Rajesh Kubde,

Chetana Makade, Swapnil Pandey (2015) undertook an in vitro study to compare the dentinal

defects caused by ProTaper Universal, Hero Shaper and ProTaper Next files. Sixty single-rooted

premolars were selected. All the specimen were decoronated and divided into four groups, each

group having 15 specimens (n=15). Group I specimens were prepared by Hand K-files (Mani),

Group II with ProTaper Universal (PT;DentsplyMaillefer), Group III with Hero Shaper

16

(HS;Micro-Mega, Besancon, France), and Group IV with ProTaperNext (PTN

;DentsplyMaillefer). Roots of each specimen were sectioned at 3, 6, and 9mm from the apex and

were then viewed under a stereomicroscope to evaluate for the presence or absence of dentinal

defects. It was observed that roots prepared with hand files (HFs) showed lowest percentage of

dentinal defects (6.7%); whereas, roots prepared with PT, HS, and PTN showed dentinal defects

in 40 %, 66.7%, and 26.7%, of the samples respectively. There was significant difference

between the HS group and the PTN group (P< 0.05). The authors concluded that dentinal defects

were observed irrespective of the type of instrumentation. However, hand instrumentation

induced minimal defects as compared to rotary instrumentation.23

Shiwani Garg, Pardeep Mahajan, Deepa Thaman, and Prashant Monga (2015) compared

dentinal damage caused by different NiTi rotary instruments during root canal preparation. One

hundred and fifty freshly extracted mandibular premolars were randomly divided into five

experimental groups of 30 teeth each (n=30) and biomechanical preparation was done: Group 1

with unprepared teeth; Group 2 were prepared with stainless steel Kfiles (DentsplyMaillefer);

Group 3 with ProTaper rotary instruments (DentsplyMaillefer); Group 4 with K3 rotary (Sybron

Endo); Group 5 with Easy RaCe rotary instruments (FKG Dentaire). Then, roots were cut

horizontally at 3, 6, and 9 mm from apex and were viewed under stereomicroscope for detection

of microcracks. Significant difference was seen between groups. No defects were found in

unprepared roots and those prepared with hand files. ProTaper, K3 rotary, and Easy RaCe

preparations resulted in dentinal defects in 23.3%, 10%, and 16.7% of teeth, respectively. More

defects were shown in coronal and middle sections, and no defect was seen in apical third. The

authors concluded that use of rotary instruments could result in an increased chance for dentinal

defects as compared to hand instrumentation.24

17

Dr. Nooruldiin A. Saeed Dr. Iman M. Al-Zaka(2015)Conducted an vitro study to compare the

effect of different Nickel Titanium instruments on the root dentin in term of dentinal defects.

Seventy-five palatal roots of maxillary first molars teeth were selected for the study. Fifteen

roots were left unprepared to serve as a negative control group; the remaining 60 roots were

divided into four tested groups. Group (I) prepared using ProTaper Universal, group (II)

prepared by EndoSequence, Group (III) prepared by ProTaper Next and finally group (IV)

prepared by RECIPROC systems. After preparation the roots were embedded in clear acrylic and

then sectioned at different levels (apical, middle and coronally) and examined under

Stereomicroscope. Results: No cracks were observed in the negative control group, while

dentinal defects were observed in roots prepared with ProTaper Universal, EndoSequence,

ProTaper Next and RECIPROC systems (28.88%, 8.89%, 11.11% and 33.33% respectively). The

results showed a nonsignificant difference between EndoSequence and Protaper Next groups and

between ProTpaer Universal and RECIPROC groups (p > 0.05), ProTaper had a significant

difference with EndoSequence and ProTaper Next groups (P < 0.05) While The RECIPROC

group had a highly significant difference with EndoSequence and ProTaper Next groups (P <

0.01). Conclusion, all instrumentation systems used in this study created cracks in the root

dentin. The EndoSequence and ProTaper Next instruments tended to cause least dentinal cracks

compared with the ProTaper Universal and RECIPROC instruments.25

Dr. Pratik Mavani, Dr. Madhu Pujar, Dr. Veerendra u ppin, Dr. Hemant Vagarali, Dr.

Chetan Patil, Dr. Viraj Yalagi conducted a study to to evaluate and compare the incidence of

root microcracks observed at apical root surface and within canal wall after canal preparations

with different rotary and reciprocating files. Ninety single rooted teeth were selected and divided

into 6 groups of 15 each. Group 1 served as a control in which no treatment was performed.

18

Teeth in Group 2, 3, 4, 5 and 6 were instrumented with ProTaper universal system, Mtwo,

K3XF, ProTaper Next system respectively in rotary motion and WaveOne system in

reciprocating motion. All roots were sectioned perpendicular to the long axis at 2 and 4mm from

the apex and were then observed under a stereomicroscope. The absence/presence of cracks was

recorded, and the data were analyzed with Fischer exact test. The significance level was set at

p=.05. The ProTaper Next and WaveOne groups showed lesser incidence of cracks as compared

to K3XF, Mtwo and ProTaper Universal groups (P < .05). Concluded that within the limitations

of this in vitro study, all of the instrumentation systems used in this study created microcracks in

root dentin.26

Huseyi .n si .nan topc¸uog lu, salih du zgu n, firdevs akpek, and gamze topc¸uog.(2016)

evaluated the effect of creating a glide path and apical preparation size on the incidence of apical

cracks during canal preparation in mandibular molar teeth with curved canals. One hundred and

forty extracted teeth were used. The teeth were randomly assigned to one control group or six

experimental groups (n=20 per group) for canal preparation. No preparation was performed on

teeth in the control group. In three of the six experimental groups, a glide path was not created; a

glide path was created on the curved mesial canals of all teeth in the remaining three

experimental groups. All teeth in experimental groups were then instrumented with the following

systems: Reciproc, WaveOne (WO), and ProTaper Next (PTN). Digital images of the apical root

surfaces of these teeth were recorded before preparation, after instrumentation with size 25 files,

and after instrumentation with size 40 files. The images were then inspected for the presence of

any new apical cracks and propagation. There was no significant difference between the

experimental groups during canal preparation using size 25 files (p>0.05). Reciproc and WO

caused more new apical cracks than did PTN during canal preparation using size 40 files

19

(p<0.05). However, canal preparation using size 40 files did not cause propagation of existing

cracks (p>0.05). Performing a glide path prior to canal preparation did not change the incidence

of apical crack during preparation. Additionally, increasing apical preparation size may increase

the incidence of apical crack during canal preparation.27

Manju Raj KuMaRi1, Manjunath MySoRe KRiShnaSwamy(2016) conducted a study to

compare and evaluate the effects of root canal preparation techniques and instrumentation length

on the development of apical root cracks. Seventy extracted premolars with straight roots were

mounted on resin blocks with simulated periodontal ligaments, exposing 1-2 mm of the apex

followed by sectioning of 1mm of root tip for better visualization under stereomicroscope. The

teeth were divided into seven groups of 10 teeth each – a control group and six experimental

groups. Subgroup A & B were instrumented with: Stainless Steel hand files (SS) up to Root

Canal Length (RCL) & (RCL –1 mm) respectively; sub group C & D were instrumented using

ProTaper Universal (PTU) up to RCL and (RCL -1mm) respectively; subgroup E & F were

instrumented using ProTaper Next (PTN) up to RCL & (RCL -1 mm) respectively.

Stereomicroscopic images of the instrumentation sequence were compared for each tooth

Stainless steel hand file group showed most cracks followed by ProTaper Universal & ProTaper

Next though statistically not significant. Samples instrumented up to 1mm short of working

length (RCL-1mm) showed lesser number of cracks.All groups showed cracks formation, the

stainless steel group being the highest. Working 1mm short of apex reduces the incidence of

crack formation.28

Marcely Cassimiro, Kaline Romeiro, Luciana Gominho, Andressa de Almeida, Larissa

Costa and Diana Albuquerque (2017) conducted a study to evaluate the frequency of dentinal

defects after root canal preparation with the ProTaper NEXT, K3XF and WaveOne GOLD

20

systems using microcomputed tomography. Sixty permanent mandibular incisors with a single

canal were selected. Inspection of the teeth was performed under a stereomicroscope (15x) to

observe the presence of pre-existing cracks and fractures lines. Samples were divided into three

experimental groups (n=20): ProTaper NEXT (PTN), K3XF (K3XF) and WaveOne GOLD

(WOG). Specimens were scanned through high-resolution microcomputed tomography before

and after the preparation of the root canal. Subsequently, all the axial images were examined by

two different methods to find possible dentinal defects. Furthermore, an analysis of each

millimeter of ten apical millimeters was also performed. The absence or presence of dentinal

defects was screened by 3 pre-calibrated blinded examiners After analysing all 45,720 slices,

dentinal defects were observed in 48.33%

(22096 slices). PTN, K3XF and WOG groups represented 11.11% (5079 slices), 17.22% (7873

slices) and 20% (n=9144) of the cross-sectional images, respectively. At 10 apical millimeters

(600 slices), 33.33% (200 slices) presented some dentinal defects, representing 7.22% (43

slices), 13.33% (80 slices) and 12.77% (77 slices) of the cross-sectional images in the PTN,

K3XF and WOG groups, respectively. All the dentinal defects presented in the postoperative

images existed in the images prior to instrumentation and concluded that there was no correlation

between the preparation of a root canal using the PTN, K3XF and WOG systems and the

formation of new dentinal defects.29

Mehmet Çitak,Taha Özyürek(2017) conducted a study to compare the dentinal defects caused

by Reciproc, TF Adaptive and ProTaper Next NiTi rotary file systems during the retreatment

procedure A total of 150 mandibular incisors with straight and single root canals were included

in the present study. All the root canals were prepared up to an apical diameter 0.40 mm using

stainless steel files. Thirty teeth were randomly stored as the negative control group. A total of

21

120 specimens were obturated with gutta-percha and AH Plus sealer using vertical compaction

technique. Thirty specimens with root canal filling were randomly separated for the only-filled

group. Then the teeth were randomly divided into 3 groups; Reciproc, TF Adaptive and ProTaper

Next. The retreatment procedure was performed with these NiTi files. Then 150 specimens were

cut perpendicular to tooth axis at 3, 6, and 9mm distances from the apex, and examined to

determine the presence of any cracks at X 25 under a stereomicroscope. Chi-squared test was

used at 5% significance level All the tested NiTi file systems were found to cause significantly

more dentinal defects compared to unprepared and only-filled groups (P<0.05). No statistically

significant differences were found between the groups in terms of dentinal defects (P>0.05). No

correlation was found between the slice levels and the dentinal defect distribution (P>0.05) and

concluded that all the tested NiTi file systems were found to cause significantly more dentinal

defects compared to unprepared and only-filled groups.30

H. melike bayryam, Emre bayram, Mert ocak , Ahmet debirham, Hakan hamdi (2017)

conducted a study to evaluate the frequency of dentin microcracks after root canal treatment with

protaper universal , protaper gold , self adjusting file, Xp- endo shaper instruments using Micro

CT. Forty human mandibular premolars with straight canals with four experimental groups

(n=10) according to different NiTi systems used for experimental groups , PTU , PTG , SAF ,

XP-ENDO SHAPER .In the SAF and Xp files first prepared till 25# k file at working length and

then SAF and X P files are used. The specimens were scanned using high resolution micro

computed tomography before and after root canal preparation. Afterwards preoperative and

postoperative cross-sectional images were scanned to identify the dentinal defects. The PTU

system postoperative specimens significantly more micro cracks than preoperative

specimens(p=<0.05).31

22

Mario Luis Zuolo,Gustavo De-Deus,Felipe Gonc¸alves Belladonna,Emmanuel Jo~ao

Nogueira Leal da Silva,Ricardo Tadeu Lopes,Erick Miranda Souza, Marco Aur_elio

Versianiand Alexandre Augusto Zaia (2017) Conducted study to evaluate the percentage

frequency of dentinal micro-cracks observed after root canal preparation with TRUShape and

Self-Adjusting File (SAF) systems by means of micro–computed tomography imaging analysis.

A conventional full-sequence rotary system (BioRace) and a single-file reciprocation system

(Reciproc) were used as reference techniques for comparison because of their known assertive

cutting efficiency. Forty anatomically matched mandibular incisors were selected, scanned at a

resolution of 14.25 mm, and assigned to 4 experimental groups (n = 10), according to the

preparation protocol: TRUShape, SAF, BioRace, and Reciproc systems. After the experimental

procedures, the specimens were scanned again, and the registered preoperative and postoperative

cross-section images of the roots (n = 70,030) were screened to identifythe presence of dentinal

micro-cracks. Overall, dentinal defects were observed in 28,790 cross-section images (41.11%).

In the TRUShape, SAF, BioRace, and Reciproc groups, dentinal micro-cracks were visualized in

56.47% (n = 9842), 42.38%(n = 7450), 32.90% (n = 5826), and 32.77% (n = 5672) of the slices,

respectively. All dentinal defects observed in the postoperative data sets were already present in

the corresponding preoperative images and Concluded that None of the preparation systems

induced the formation of new dentinal micro-cracks.32

Ekta garg, shafia sarfi , dildeep bali , akhil k garg(2017)Conducted a study to evaluate and

compare the incidence of dentinal defects induced by Hand Files, HyFlex CM, ProTaper Next

(PTN), and One Shape during canal preparation. Materials and Methods: One hundred and fifty

extracted mandibular premolar teeth with single root canal were selected. Specimens were then

divided into five groups with thirty specimens each. Group I: Specimens were prepared with

23

hand instruments. Group II: Specimens were prepared with HyFlex CM rotary files (Coltene)

using a crown-down technique according to the manufacturer’s instructions. Group III:

Specimens were prepared with PTN rotary files (Dentsply) using a crown-down technique

according to the manufacturer’s instructions. Group IV: Specimens were prepared with One

Shape Single file rotary system (MicroMega) using a crown-down technique according to the

manufacturer’s instructions. Group V: Specimens were used as a control and left unprepared. All

roots were cut horizontally at 3, 6, and 9 mm from the apex. Sections were then viewed under

stereomicroscope and dentinal defects were registered as “no defect,” “fracture,” and “other

defects.”Results were expressed as the number and percentage of defected, partially defected and

roots with no defects in each groups. Concluded thatHand files and One Shape file system

caused less root defects compared to PTN and HyFlex file systems.33

Suparna Ganguly Saha, Neelam Vijaywargiya, Divya Saxena, Mainak Kanti Saha1, Anuj

Bharadwaj, Sandeep Dubey(2017) conducted a study to evaluate the incidence of microcrack

formation canal preparation with two rotary nickel–titanium systems Mtwo and ProTaper Next

along with the self�adjusting file system.One hundred and twenty mandibular premolar teeth

were selected. Standardized access cavities were prepared and the canals were manually

prepared up to size 20 after coronal preflaring. The teeth were divided into three experimental

groups and one control group (n = 30). Group 1: The canals were prepared using Mtwo rotary

files. Group 2: The canals were prepared with ProTaper Next files. Group 3: The canals were

prepared with self�adjusting files. Group 4: The canals were unprepared and used as a control.

The roots were sectioned horizontally 3, 6, and 9 mm from the apex and examined under a

scanning electron microscope to check for the presence of microcracks. The Pearson’s

Chi�square test was applied. Results: The highest incidence of microcracks were associated

24

with the ProTaper Next group, 80% (P = 0.00), followed by the Mtwo group, 70% (P = 0.000),

and the least number of microcracks was noted in the self�adjusting file group, 10% (P = 0.068).

No significant difference was found between the ProTaper Next and Mtwo groups (P = 0.368)

while a significant difference was observed between the ProTaper Next and self�adjusting file

groups (P = 0.000) as well as the Mtwo and self�adjusting file groups (P = 0.000). Concluded

that all nickel–titanium rotary instrument systems were associated with microcracks. However,

the self�adjusting file system had significantly fewer microcracks when compared with the

Mtwo and ProTaper Next.34

Akshayraj K Langaliya, Anjali K Kothari, Nishantkum ar R Surti, Amiben R Patel, Prerak

R Doshi1, Devarshi J Pandya(2018) conducted a study to evaluate and compare dentinal

microcracks formation during root canal preparation by different commercially available

nickel-titanium (NiTi) file systems. Eighty-four single-rooted mandibular premolars were

selected. All specimens were decoronated and divided into seven groups of 12 each.Twelve teeth

served as a control in which no treatment was performed. Experimental groups were

instrumented with Hand NiTi, ProTaper universal, ProTaper Next, Silk, WaveOne, and

self-adjusting files (SAF). SAF group and Hand NiTi group showed no cracks formation along

with control group. ProTaper rotary files showed more number of cracks than ProTaper Next,

Silk and WaveOne used in the study. However, no statistically significant difference was found

among ProTaper rotary, ProTaper Next, Silk, and WaveOne (P > 0.05). Concluded that All

rotary files created microcracks in the root dentin at all three levels, whereas the SAF and hand

files presented with satisfactory results with no dentinal microcracks.35

Sonalkumari vakilram nishad, g. B. Shivamurthy(2018)conducted a study to compare the

incidence of apical root crack formation after root canal preparation at different instrumentation

25

lengths using ProTaper Universal (PTU), ProTaper Next (PTN) and ProTaper Gold (PTG) file

systems.Eighty-four mandibular first premolars with single and straight root canal were mounted

in resin block after simulating periodontal ligaments. 1–2 mm of root apex was exposed followed

by sectioning of 1 mm of root tip for better stereomicroscopic visualization. While the Control

group was left unprepared, experimental groups were instrumented up to root canal length (RCL)

and (RCL-1 mm) respectively using PTU, PTN and PTG. After staining the root apex with 1%

methylene blue dye, stereomicroscopic images were obtained for evaluating apical root

cracks.Significantly less dentinal defects were seen between PTG and PTU while there was no

significant difference between PTU-PTN and PTN-PTG. Furthermore, samples instrumented up

to RCL-1 mm showed lesser cracks as compared with samples instrumented up to RCL.

Concluded that PTG produced least number of cracks followed by PTN and PTU. Furthermore,

instrumenting short of RCL reduced the crack formation risk.36

Sanjib Das, Prasanti Kumari Pradhan, S. Lata, Sachidananda Prasad Sinha(2018)

conducted a study to compare the incidence of dentinal crack formation after root canal

preparation using ProTaper Next, OneShape, and Hyflex electrodischarge machining (HEDM)

.A total of 75 extracted mandibular premolars were selected. The root canals were instrumented

using ProTaper Next, OneShape, and HEDM rotary files. All roots were horizontally sectioned at

3, 6, and 9 mm from apex with slow-speed saw under water cooling. The sections were observed

under a stereomicroscope at ×25 to determine the absence or presence of crack. Data were

analyzed using post hoc test and one-way ANOVA. ProTaper Next and HEDM produced

significantly less cracks than OneShape. Concluded that Within the limitation of this in vitro

study, nickel–titanium instruments may cause cracks on the root surface. ProTaper Next and

HEDM tend to produce less number of cracks as compared to OneShape.37

26

MATERIAL AND METHODOLOGY

Ethical clearance

The synopsis of the proposed study was prepared and submitted to the chairperson, Institutional

review board, H.K.E.S S. Nijalingappa Institute of dental sciences and research for ethical

approval. After extensive review and scrutiny by the board members, approval was granted to

conduct the study.

Study Design: In-Vitro study

Source of data:

100 Freshly extracted human mandibular first premolar teeth were collected from the

Department Of Oral and Maxillofacial Surgery, H.K.E.S’s S.N. Dental Sciences and

Research.

MATERIALS:

1) 100 extracted mandibular 1st premolar teeth.

2) Airotar hand piece (NSK).

3) Conventional hand K file (DENTSPLY, Maillefer, Ballaigues, Switzerland).

5) Micro Motor Hand Piece (NSK).

6) Carborundum disc.

4) Rotary files –

a) Twisted File (TF; Sybronendo, Orange, CA).

b) Self -Adjusting File (ReDent-Nova, Ra’anana, Israel).

c) Pro Taper Next (DENTSPLY, Maillefer).

27

7) 3%Naocl

8) Distilled water.

9) EDTA gel (GLYDE, DENTSPLY).

2. Stereomicroscope (Leica Microsystems Ltd, S8 APO)

3. X-smart or X –smart plus rotary system (DENTSPLY).

4. Endo station rotary system.

Procedure:

METHOD OF DATA COLLECTION:

Sample Collection: Hundred freshly extracted human mandibular first premolars were collected

from the Department of Oral & Maxillofacial Surgery, H.K.E. Society’s Nijalingappa institute of

dental sciences and research. Immediately after extraction, the teeth were rinsed under running

water and stored in specimen bottles filled with distilled water. This storage medium causes the

smallest changes in dentin over time and was previously recommended for investigations of

human dentin.

Sample Size: Hundred single rooted human mandibular first premolars were randomly selected

from the sample collected as mentioned above which met the inclusion and exclusion criteria.

Equipment

1. Precision saw (Buehler, an ITW Company, Illinois, USA)

28

Selection of Teeth: All the teeth were radiographed in both buccolingual and mesiodistal

directions using radiographs to detect the presence of single canal and each tooth was studied.

Inclusion criteria:

1)Sound teeth with intact root

2) Non carious teeth

3) Teeth with no anomalies

Exclusion criteria:

1) Fractured teeth

2) Teeth with crack

3) Previously restored teeth

4) Teeth with any root caries

PREPERATION OF SPECIMENS

All the teeth were cleaned of tissue fragments and visible debris using ultrasonic scaler (EMS,

Switzerland) and were stored in distilled water until use. To standardize canal instrumentation,

teeth were decoronated by using carborundum disc, establishing a standardized root length of 12

± 1mm(millimeter). All roots were inspected with a stereomicroscope (Leica Microsystems Ltd,

S8 APO) under 12 x magnification to detect any pre-existing craze lines or cracks. Teeth with

29

such findings were excluded and replaced with similar teeth in the study. During the study,

specimens were wrapped in 4×4 gauze and kept moist

A standard model for periodontal ligament simulation were used for all groups. Roots were

placed in melted wax up to 1mm below the coronal end. After cooling, they were embedded in 2

X 2 X 2 cm(centimeter) blocks filled with clear acrylic resin. After setting, the roots were made

cleared of wax from root surface and socket using warm water. Sockets were then filled with a

silicone impression material (AQUASIL, LIGHTBODY, and DENTSPLY) and roots were

reinserted in to the respective sockets. The excess impression material were removed with a

scalpel.

A total of 100 samples taken out of which, 20 samples were left unprepared and considered as a

control group. Remaining 80 samples were divided according to the instrumentation techniques

into four groups of 20 samples each and these groups were further divided into two subgroups

of 10 samples each accordingly , with and without use of EDTA gel as a lubricanting agent

during canal instrumentation

GROUP 3 - Self-Adjusting File (n=20)

Sub group 3(a) - Self-Adjusting File with using EDTA (n=10)

GROUP 1- Hand K file (n=20)

Sub group 1(a)- Hand K File with using EDTA (n=10)

Sub group 1(b)- Hand K file without using EDTA(n=10)

GROUP 2 - Twisted file (n=20)

Sub group 2(a)- Twisted file with using EDTA (n=10)

Sub group 2(b)- Twisted file without using EDTA(n=10)

30

Sub group 3(b) - Self-Adjusting File without using EDTA (n=10)

GROUP 4 - ProTaper Next File (n=20)

Sub group 4(a) - ProTaper Next file with using EDTA (n=10)

Subgroup 4(b) - ProTaper Next file without using EDTA (n=10)

GROUP 5 - Control group (intact root without any root canal preparation) (n=20)

Sub group 5(a) – control group with EDTA (n=10)

Sub group 5(b)- control group without EDTA (n=10)

Preparation of canal:

Canals were negotiated with size #10 K files and after removal of gross pulpal tissue, working

length was established by advancing file into canal until just visible at the apical foramen and

then subtracting 1 mm from it. Then glide path was established by using 15-k file.

Rotary instruments were set into rotation with a 16:1 reduction hand piece powered by a torque-

limited endo motors (X-smart TMplus or X Smart Dentsply Tulsa Dental). For each file, the

individual torque limit and rotational speed recommended by the manufacturer were used.

Canals were prepared according to the following protocol. Self-Adjusting file was used as per

manufacturer’s instructions.

Root canals were irrigated with 2ml of 3% sodium hypochlorite solution. After preparation the

specimen from the prepared groups were rinsed with 5ml distilled water.

GROUP1: HAND FILE

Canals were enlarged up to #40 size and followed bystep back technique till 70# k file.

GROUP 2: TWISTED FILE

31

Establishing an apical glide path using 15# k file and enlarged till 20# k file. Then Canals were

prepared in a crown down fashion with asequence of files #25/.08, #25/.06 at a speed of

500rpm(revolutions per minute) with torque of 4N-cm(newton-cetimeter).With the file rotating

as it enter the canal, the file was advanced slowly with a single continuous and controlled motion

with a minimum force until the file engages dentin, then the file was withdrawn. The filing was

done up to 25 with taper of 0.06%.

GROUP 3: SELF ADJUSTING FILE

The instrumentation was done according to the manufacturer's instructions after establishing an

apical glide path using 15# k file and enlarged till 20# k file. The 1.5 mmfile was used with an

in-and-out vibrating motion using a RDT3 handpiece (ReDent Nova, Ra'anana, Israel) at an

amplitude of 0.40 mm and at 5000 vibrations/min. The self-adjusting file was used in a pecking

motion to the working length for 4 min in each tooth.

GROUP 4: PROTAPER NEXT

Establishing an apical glide path using 15# k file and enlarged till 20# k filethen canals were

prepared in a crown down fashion with a sequence ofthe ProTaper shaping SX was used in

coronal enlargement then X1(17/0.04),X2 (25/0.06) files with a speed of 250 rpm at torque

4.0N-cm to the working length.

GROUP 5: CONTROL GROUP

Unprepared root canal shaping group (Control Group)

Sectioning and Microscopic Examination

32

All roots were sectioned perpendicular to long axis at 3mm, 6mm, 9mm from apex using a low

speed saw under water cooling to examine micro dentin cracks in apical third, middle third

andcoronal third of root a total of 30 sections in each subgroup. Digital images of each section

were captured at 25X magnifications using a digital stereomicroscope. Microscopic

examinations of specimens were done to examine micro dentin cracks. In order to avoid

confusing definitions of root fractures, three distinguished categories were made: no cracks,

complete cracks and partial crack. According to Wilcox et al root dentin defects were classified

as craze line, partial crack or a fracture. For the sake of simplicity, the root dentinal defects was

categorized as Type I defect which includes complete crack line while Type II defect includes

craze line and partial crack.

No cracks Root dentin without cracks or craze lines either at the

internal surface of the root canal wall or at the external

surface of the root.

Complete crack A line extending from the inner root canal space all the way

to the outer surface of the root.

Partial crack A line extending from the canal walls into the dentin without

reaching the outer surface.

Craze line A line extending from the outer canal walls into the dentin

without reaching the canal lumen.

Table no. 1 Types of root dentinal cracks

33

Figure1: Specimens

34

Figure 2: Specimens mounted in epoxy resin blocks(2X2X2cm)

Figure 3: Coronal sectioning

Figure 4: Standardisation of root length

35

Figure 5: Decoronated sectioned sample

Figure 6: Samples divided in to groups

Figure 7: Armamentarium

36

Figure 8: Hand k file group

Figure 9 : Twisted fIle group

37

Figure 10 : Protaper Next File group

Figure 11: Self Adjusting file group

38

Figure12: Cleaning and shaping of specimens with Hand K file,Twisted Adaptive file, Self

Adjusting File and Protaper Next file

Figure 13: Isomet saw low speed saw Buehler

39

Figure 14: Sectioned sample of 9mm,6mm,3mm

Figure15: Digital stereomicroscope

40

RESULT

Stereomicroscopic images showing No defects, Type 1 defects and Type 2 defects at

3mm,6mm,9mm

Figure16: Stereomicroscopic images showing No defects at 3mm,6mm,9mm

3mm section 6mm section

41

9mm section

Figure17: Stereomicroscopic images showing Type I defects at 3mm,6mm,9mm


9mm section

42

Figur18 : Stereomicroscopic images showing Type II defect at 3mm, 6mm, 9 mm section


9mm section

43

Results are expressed in number and percentage of dentinal defects in each subgroup. Dentinal

defects in each section was observed regardless the number of defects. Fischer’s exact test was

used to compare the different dentinal defects between each experimental groups and subgroups

by using SPSS computer program. The level of significance was set at p<0.05.

In this study 100 samples of mandibular first premolar were decoronated and roots were

embedded in the resin blocks. Twenty samples were left unprepared (control group) and

remaining 80 samples were divided into four groups. Each group was divided equally into two

sub groups, where each sub group contains 10 samples.

Present study observed that the maximum number of root dentinal defects was found with EDTA

than without EDTA in all the groups. While comparison of root dentinal defects among different

groups, it was found that group 4 (PTN) secured the highest place in both, with and without

EDTA subgroups.

Table no.2 represents root dentinal defect as a result of root canal instrumentation in all groups.

Group 2 (TF) and Group 4(PTN) showed more no.of defects in both the subgroups that is 36.7%

(with EDTA) and 30% (without EDTA), 43.3% (with EDTA) and 33.3% (without EDTA)

respectively.

The value was comparatively less among group 1 and Group 3 that is 26.7% (with

EDTA) and 16.7% (without EDTA), 10% (with EDTA) and 6.7% (without EDTA) respectively.

There was statistically highly significant difference of root sections of dental defects between the

groups in with EDTA and without EDTA (P<0.01) as shown in the same Table no.2.

44

There was no statistical significant difference in the type of root dentinal defects between the sub

groups within each group and also the between the groups in the root section at 9mm, 6mm and

3mm (P>0.05) shown in Table no 3, 4 and 5.

In detail significance among various groups are explained in detail in Table no.6.

Table No.2: The percentage and number of root dentinal defects at different root level as a result of root canal instrumentation in all groups.

Groups

Subgroups

(N = 10)

Root sections with no. of

dental defects

Total no.

of dental

defects

Percentage

9mm 6mm 3mm

Group 1

Hand K-file

With EDTA (1a) 2 3 3 8 26.7

Without EDTA (1b) 1 2 2 5 16.7

Group 2

Twisted file (TF)

With EDTA (2a) 3 4 4 11 36.7


Group 3

Self adjusting file

With EDTA (3a) 0 1 2 3 10.0


Group 4

Protaper Next (PTN)

With EDTA (4a) 6 3 4 13 43.3

Without EDTA (4b) 4 2 4 10 33.3

Group 5

Control group

With EDTA (5a) 0 0 0 0 0.0


Fisher Exact

Probability Test

P- value & sign

With EDTA

P = 0.00054

Highly significant

--

Fisher Exact

Probability Test

P- value & sign

Without EDTA P = 0.00676

Highly significant

--

Figure 19: The percentage and number of root dentinal defects at different root level as a result of root canal instrumentation in all groups.

0

5

10

15

20

25

30

35

40

45

26.7

16.7

Ro

ots

pre

sen

tin

g d

efe

cts

in p

erc

en

tag

e

45

The percentage and number of root dentinal defects at different root level as a result of root canal instrumentation in all groups.

36.7

30

106.7

43.3

33.3

Groups

The percentage and number of root dentinal defects at different root

0 0

46

Table No.3: Comparison of types of root dentinal defects between the all groups as a result

of root canal instrumentation in sub group with EDTA gel

Groups

Root sec. at 9mm (N

=10)

Root sec. at 6mm

(N =10)

Root sec. at 3mm

(N =10)

Type I

No (%)

Type II

No (%)

Type I

No (%)

Type II

No (%)

Type I

No (%)

Type II

No (%)

Group 1

Hand K-file (1a)

0 (0.0) 2 (20.0) 1 (10.0) 2 (20.0) 1 (10.0) 2 (20.0)

Group 2

Twisted file (TF)(2a)

1 (10.0) 2 (20.0) 0 (0.0) 4 (40.0) 1 (10.0) 3 (30.0)

Group 3

Self Adjusting

File(SAF)(3a)

0 (0.0) 0 (0.0) 0 (0.0) 1 (10.0) 1 (10.0) 1 (10.0)

Group 4

Protaper Next (PTN)(4a)

1 (10.0) 5 (50.0) 0 (0.0) 3 (30.0) 2 (20.0) 2 (20.0)

Group 5

Control group(5a)

0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0)

Fisher Exact Probability

Test

P- value & sign

P = 0.364

NS

P = 0.739

NS

P = 0.145

NS

NS = Not significant

Figure 20: Multiple bar diagram representscomparison of types of

between the all groups as a result of root canal instrumentation of sub group with EDTA

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Hand K-

file(With

EDTA)

Twisted file

(With EDTA)

0

1

2 2

1

2

1

2

No

of

roo

t se

ctio

ns

pre

sen

tin

g d

efe

cts

47

Multiple bar diagram representscomparison of types of


Twisted file

(With EDTA)

Self

adjusting

file(With

EDTA)

Protaper

Next(With

EDTA)

Control

group

0

1

0

2

0

5

00 0 0 0

4

1

3

1 1

2

3

1

2

Groups

Multiple bar diagram representscomparison of types of root dentinal defects


Control

group

0 0 0

Type I (9mm)

Type II (9mm)

Type I (6mm)

Type II (6mm)

Type I (3mm)

Type II (3mm)

48

Table No.4: Comparison of types of root dentinal defects between the all groups as a result

of root canal instrumentation of sub group without EDTA gel

Groups

Root sec. at 9mm (N

=10)

Root sec. at 6mm

(N =10)

Root sec. at 3mm

(N =10)

Type I

No (%)

Type II

No (%)

Type I

No (%)

Type II

No (%)

Type I

No (%)

Type II

No (%)

Group 1

Hand K-file (1b)

0 (0.0) 1 (10.0) 0 (0.0) 2 (20.0) 0 (0.0) 2 (20.0)

Group 2

Twisted file (TF)(2b)

0 (0.0) 1 (10.0) 1 (10.0) 3(30.0) 2 (20.0) 2 (20.0)

Group 3

Self Adjusting File(3b)

0 (0.0) 0 (0.0) 0 (0.0) 1 (10.0) 0 (0.0) 1 (10.0)

Group 4

Protaper Next (PTN)(4b)

1 (10.0) 3 (30.0) 0 (0.0) 2 (20.0) 1 (10.0) 3(30.0)

Group 5

Control group(5b)

0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0)

Fisher Exact Probability

Test

P- value & sign

P = 0.213

NS

P = 0.552

NS

P = 0.278

NS

Figure 21: Multiple bar diagram representscomparison of types of between the all groups as a result of root canal instrumentation of sub group without EDTA

0

0.5

1

1.5

2

2.5

3

Hand K-

file(Without

EDTA)

0

1

0

2

0

2

No

. o

f ro

ot

sect

ion

s p

rese

nti

ng

de

fect

s

49

Multiple bar diagram representscomparison of types of between the all groups as a result of root canal instrumentation of sub group without

Twisted file

(Without

EDTA)

Self adjusting

file(Without

EDTA)

Protaper

Next(Without

EDTA)

Control group

0 0

1

0

1

0

3

1

0 0

3

1

22

0

1

2

1

3

Groups

Multiple bar diagram representscomparison of types of root dentinal defects between the all groups as a result of root canal instrumentation of sub group without

Control group

0 0 0 0 0

Type I (9mm)

Type II (9mm)

Type I (6mm)

Type II (6mm)

Type I (3mm)

Type II (3mm)

50

Table No.5: Comparison of root dentinal defect as a result of root canal instrumentation

between the sub groups within the group.

Groups

Subgroups

(N = 10)


dental defects

Total no.

of dental

defects

Fisher Exact

Probability

Test

P- value&

sign.

9mm 6mm 3mm

Group 1

Hand K-file

With EDTA (1a) 2 3 3 8 P = 0.131

NS Without EDTA (1b) 1 2 2 5

Group 2

Twisted File (TF)

With EDTA (2a) 3 4 4 11 P = 0.423


Group 3

Self Adjusting

File(SAF)

With EDTA (3a) 0 1 2 3 P = 0.664


Group 4

Protaper Next (PTN)

With EDTA (4a) 6 3 4 13 P = 0.275


Group 5

Control group

With EDTA (5a) 0 0 0 0 ---

Without EDTA (5b) 0 0 0 0

Study reveals that, there was no statistical significant difference of dentinal defectsamong with

and without EDTA gel in all the groups (P>0.05)

51

Table No.6: Comparison of root dentinal defect as a result of root canal instrumentation

between the groups

Groups

Subgroups

(N = 10)


dental defects

Total no. of

dental defects

9mm 6mm 3mm

Group 1

Hand K-file

With EDTA (1a) 2 3 3 8


Group 2

Twisted File (TF)

With EDTA (2a) 3 4 4 11


Group 3

Self Adjusting File



Group 4

Protaper Next (PTN)

With EDTA (4a) 6 3 4 13


Group 5

Control group



Comparison between group 1 with group 2, group 3, group 4 and group 5

Group 1 and 2 � P = 0.078 not significant

Group 1 and 3 � P = 0.013 significant


Group 1 and 5 � P = 0.00000 highly significant





52












53

DISCUSSION

The basic goals that are required for a chemomechanical preparation are cleaning and shaping of

the root canal. These objectives could be achieved simultaneously during preparation through the

use of instruments and irrigants. Chemomechanical preparation assumes a pivotal role in

treatment because it acts mechanically and chemically on bacterial communities colonizing the

main canal.36

Rotational forces generated during the use of Ni-Ti rotary instruments can lead to dentinal

defects such as cracks and craze lines, and geometrical properties and mechanical behaviours of

the instruments can influence the degree of crack formation.22

The number and percentage of such defect formation is may be due to file design, crosssectional

geometry, alloy of instrument, constant or progressive taper type, constant or variable pitch, and

flute form.37

The use of EDTA gel during rotary instrumentation is to reduce incidence of instrument

separation and facilitate instrument procedure. This lubricant can reduce rotational and frictional

forces on radicular dentinal walls and may theoretically reduce incidence of dentinal defects.38

EDTA is a demineralization agent used for the removal of smear layer, and long-time exposure

of root dentin to 17% EDTA may lead to dentinal erosion and significantly reduce its

microhardness, whichsubsequently increases the fracture susceptibility of the teeth.In the present

study was to evaluate the possible effects of EDTA gel as a lubricant during root canal

instrumentation using hand files, twisted files, protaper next files and self-adjusting file systems

on the incidence of radicular dentinal damage in the form of micro cracks in root dentin.39

54

In the present study,Mandibular first premolars were selected for the study because of the high

prevalence of VRF as reported by Tamseet al. Mandibular premolars of nearly same root length

taken to minimize the anatomical variations It was also reported that occlusal load on

mandibular premolars during chewing is three times as high as the other teeth42. The root

surfaces were covered with a silicone impression material in clear acrylic resin blocks to

simulate periodontal ligament and distribute stresses during root canal preparation as it has

viscoelastic properties similar to periodontal ligament.40, 15, 27

The samples of the present study were sectioned with a saw under water cooling. The sectioning

of roots is a widely used method to determine dentinal defects. Numerous studies have used this

method and revealed that the control group sections were devoid of cracks, so concluded that

defects were as a result of different instrumentation techniques.41

File design is also likely to affect the shaping forces on the root dentin. Forces generated during

instrumentation have been linked to an increased risk of root fracture. During preparation, a

canal is shaped by the contact between instrument and dentin walls.Higher stresses in the root

during instrumentation can be expected to increase dentinal defects and thus increase VRF risk.42

But in the present study whatever the file design there is an incidence of crack formation which

varies in percentage but not seen in control group.

In the present study, the percentage ofroot dentinal cracks with and without EDTA in stainless

steel hand k-file was 26.7%&16.7% respectively. These were in accordance with study

conducted by Adorno, Yoshikoa, H. Suda. Yoldas et al. Hin et al. and this could be attributed to

the less aggressive movements of the hand files in the canal compared with engine-operated files

in which there is more aggressive rotation of Ni-Ti instruments.20

55

Milanialso showed that technique of hand instrumentation may influence the crack formation.

Balanced force produced significantly less cracks than step back technique.43

The number of rotations required for complete root canal preparation is more with NITi

instruments than with the hand files. Additionally, it has been suggested that the total volume of

dentin removed from the root canals was significantly greater with NiTi rotary systems in

comparison with hand files, which implicates more problems that might affect prognostic

stability of the teeth..3, 43 Thus a general conclusion can be drawn that hand files result in less

dentinal cracks than rotary files.

PTN file is the newest innovation to the ProTaper Universal system, which has been the gold

standard in endodontics for many years. It has M-wire technology with an off-centered

rectangular cross-section, giving the file a snake�like swaggering movement as it moves along

the root canal.32

In the present study PTN file with EDTA and without EDTA showed 43.3% & 33.33 cracks

which is a highest compared to all other groups. R.Ambikakumari and Madhudhi S.

vishwasstudied the incidence of dental cracks by using TFA(twisted file adaptive),WOG(wave

one gold),PTN in which PTN showed highest number of cracks , continuous rotation caused

more cracks than reciprocation and adaptaion.44 Arbabchirani et al45 were also reported that

protaper rotary associated files causing more dentinal cracks than other nickel titanium files

because of their larger cross-sections, high stiffness, high level of torque and bending force.

This is also in accordance with the study done by Ektagarget al., to compare hand instruments,

ProTaper Next files, HyflexCM(controlled memory) and One shape. He concluded that the

ProTaperNext files produced more number of dentinal microcracks.32

56

Twisted Files (Sybron endo) has a triangular cross�section. They are non�landed with positive

rake angles. TF instruments are created by taking a raw NiTi wire in the austenite crystalline

structure and transforming it into a different crystalline structure rhombohedral (R�phase), by a

process of heating and cooling. In the R�phase, NiTi cannot be ground, but it can be twisted.

Once twisted, file is heated and cooled again to maintain its new shape and convert it back into

austenite crystalline structure, which is superelastic once stressed.46

In this study with EDTA and without EDTA Twisted files produced 36.7% & 30% micro

dentinal cracks. It was also observed that the maximum number of root dentinal defects in group

4 (PTN) followed by group 2(TF). These results can be explained with the fact that the twisted

files have the property of increased flexibility and minimal canal transportation and maintains

original shape of the canal which induces less stress on the root dentin and eventually leads in

less dentinal cracks.

The observation found in this study is supported by previous literature. Xin ZHOU47studied and

also concluded that TF shows less no number of dentinal defects due to its increased flexible

nature and maintains canal shape and adapts to the canal.

The self-adjusting file (SAF; ReDent-Nova, Raanana, Israel) represents a new approach in file

design and mode of operation. The file is a hollow device, designed as a cylinder of thin-walled,

delicate NiTi lattice with a lightly abrasive surface.Offset design produce a mechanical wave of

motion that travels along the active length of the file. Like the progressively percentage tapered

design of any given ProTaper file, this offset design serves to further minimize the engagement

between the file and dentin .48

57

In this study self-adjusting file with and without EDTA showed 10% and 6.7% of micro dentinal

cracks. In group1 (Hand k file) and group 3 (SAF) the no.of dentinal defects and type I dentinal

defect were very less as compare to group 2 and group 4.

Hand k-files and self-adjusting file showed less number of cracks this might be due to less

number of rpm, no torque. Hence from this study, we can say that it exerts less pressure on root

canal and they have a constant Taper -0.02.

Ellemiekes has performed a study and showed that SAF produced more number of incomplete

cracks and no complete crack was formed. It creates less stress on canal wall and continuous

irrigation through SAF may minimize friction and facilitates removal of dentin.12

Rui Li et al. said that SAF has neither cutting edge, nor flutes and operates like sand paper

removing the dentin producing no cracks.11

The results of the present study showed that all canal instrumentation techniques produced

dentinal defects. The degree of significance varied within group (with and without EDTA) and

between the groups. This result is consistent with previous studies that demonstrated increased

crack formation and fracture susceptibilityof teeth as a result of instrumentation49

However, when NaOCl followed EDTA, NaOCl directly attached to the collagen which had

already been exposed by demineralization. About 70- 75% of the mineral was removed rapidly,

while the remaining mineral etched at a significantly slower rate. Hence dentin erosion occurred

markedly when NaOCl followed EDTA.50Changes in the organic and inorganic components of

dentin will also affect the mechanical properties of dentin. It is shown that the mineral

component in hard connective tissues contributes to strength and elastic modulus, whereas the

collagen component is responsible for toughness of the tissues.51

58

The use of EDTA gel in this study insignificantly increased the percentage of dentinal defects

and the type of defect at different level of root sections in all experimental groups. This may be

explained by the gel form of EDTA, which may collect more debris in the cutting flutes of the

files decreasing the cutting efficiency of the file and indirectly increasing the stress on the

dentinal wall and enhancing dentinal crack formation.22

By the above explanation, the benefits of using EDTA as lubricating agent without interfering

with the efficacy of the agent is more than its disadvatages which is common with all the

lubricating agents available in the market today.

Furthermore, studies using EDTA in different concentrations or other chelators at different time

intervals, in the same manner as the present study, may help the clinician to get a clear idea.

LIMITATIONS OF THE STUDY

1. Regarding sectioning method has some limitations.

Besides the inability to detect pre-existing defects, it is possible that some pre-existing defects

can extend to different levels of the root and counted as defects. Crack lines and craze lines along

the longitudinal surfaces can go undetected during sectioning methods.

2. Stereomicroscopic observations

Every sophisticated equipment inherent some percentage of errors and thus are not 100%

accurate. Light reflection on root surface make identification of dentinal cracks difficult

and may have resulted in greater observer inaccuracy.

3. The use of different speed and torque settings for each file system during the procedure

could be a limitation of the present study.

59

CONCLUSION

1. The incidence of root dentinal micro cracks after root canal preparation with different

endodontic file system with EDTA was comparatively more than without EDTA.

2. The no. of root dentinal defects were highest with Protaper next group then followed by

twisted file group. Comparatively very less no.of root dentinal defects were observed in

Self-adjusting file group and Hand K-file group.

3. Type I dentinal defects (complete crack) was seen more in Protaper next and twisted file

in comparison to self-adjusting file and hand k-file.

4. At different level of root sections, 3mm root sections show more no.of dentinal defects

than in 6mm and 9mm. This is can be due to thin less dentine thickness to counteract the

lateral stresses generated by instrumentation.

Thus wise decision must be taken by the clinican considering the root dentin thickness

and root canal anatomy correspondingly use the suitable file system.

60

SUMMARY Biomechanical preparation of root canals is one of the main steps in achieving endodontic

success due to enabling bacterial elimination, removal of debris and facilitating obturation.

A frequent reason for tooth loss after root canal treatment is vertical root fracture.

Instrumentation of root canal alone significantly reduced resistance to fracture of teeth. Different

preparation techniques and file designs have identified as being responsible for degrees of

dentinal damage and induction of micro cracks.

In the present study an attempt was made to evaluate the incidence of root dentin micro cracks

after root canal preparation with different endodontic file system like hand k-files, twisted files,

self-adjusting file and protaper next files with and without EDTA.

The result showed that the maximum number of root sections of dentinal defects in group 4

(PTN) with EDTA 43.3% without EDTA 33.3% followed by group 2 (TF) with EDTA 36.7%

without EDTA 30.0%then group 1(Hand k-File) shows 26.7% with EDTA and 16.7% without

EDTAand least number of dentin defectswas seen in group 3 (SAF) with EDTA 10% and

without EDTA 6.7% due to its tear drop cross section and adaptation to root canal anatomy.

Control group showedno dental defects.The incidence and types of dentinal defects were

statistical significant difference is seen between groups and insignificant within each group when

analyzed and compared.

The use of EDTA gel in this study insignificantly increased the percentage of dentinal defects

and the type of defect at different level of root sections in all experimental groups. This may be

explained by the gel form of EDTA, which may collect more debris in the cutting flutes of the

61

files decreasing the cutting efficiency of the file and indirectly increasing the stress on the

dentinal wall and enhancing dentinal crack formation.22

By the above explanation, the benefits of using EDTA as lubricating agent without interfering

with the efficacy of the agent is more than its disadvantages which is common with all the

lubricating agents available in the market today.

62

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Dept. of Prosthodontics and Crown & Bridge H.K.E.S’s S.N Institute of Dental Sciences & Research, KalaburagiPage 62

H.K.E.S’s. S.NILALINGAPPA INSTITUTE OF DENTAL SCIE NCES & RESEARCH

PATIENT CONSENT FORM

I _____________________________ do state that I hereby declare that in my complete

consciousness am ready to undergo investigation / examination / treatment or any other

necessary procedure carried out by Dr. T. NANDA KUMAR who is undertaking a research

work titled “COMPARISON OF DIFFERENT ENDODONTIC FILE SYSTEMS

ON THE INCIDENCE OF ROOT DENTINAL DEFECTS WITH AND

WITHOUT EDTA – A STEREOMICROSCOPIC ANALYSIS.”and the time

duration is of 6 MONTHS. I have been assured of my confidentiality and do not involve any

sort of extra / incidental expenses to me related to research. I can withdraw from the research

at any given point of time. The whole procedure was explained to me in my own language

and I whole heartedly agree to give my consent.

SIGNATURE

Proforma

Dept. of Prosthodontics and Crown & Bridge H.K.E.S’s S.N Institute of Dental Sciences & Research, Kalaburagi Page 64

PROFORMA FORMAT (USED FOR DOCUMENTATION)

The study undertaken was an in-vitro study, for which only Extracted teeth were used. Thus

proforma was not applicablefor the same.