“ 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
XV
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
3mm section 6mm section
9mm section
42
Figur18 : Stereomicroscopic images showing Type II defect at 3mm, 6mm, 9 mm section
3mm section 6mm 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
Without EDTA (2b) 1 4 4 9 30.0
Group 3
Self adjusting file
With EDTA (3a) 0 1 2 3 10.0
Without EDTA (3b) 0 1 1 2 6.7
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
Without EDTA (5b) 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
between the all groups as a result of root canal instrumentation of sub group with EDTA
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
between the all groups as a result of root canal instrumentation of sub group with EDTA
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)
Root sections with no. of
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
NS Without EDTA (2b) 1 4 4 9
Group 3
Self Adjusting
File(SAF)
With EDTA (3a) 0 1 2 3 P = 0.664
NS Without EDTA (3b) 0 1 1 2
Group 4
Protaper Next (PTN)
With EDTA (4a) 6 3 4 13 P = 0.275
NS Without EDTA (4b) 4 2 4 10
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)
Root sections with no. of
dental defects
Total no. of
dental defects
9mm 6mm 3mm
Group 1
Hand K-file
With EDTA (1a) 2 3 3 8
Without EDTA (1b) 1 2 2 5
Group 2
Twisted File (TF)
With EDTA (2a) 3 4 4 11
Without EDTA (2b) 1 4 4 9
Group 3
Self Adjusting File
With EDTA (3a) 0 1 2 3
Without EDTA (3b) 0 1 1 2
Group 4
Protaper Next (PTN)
With EDTA (4a) 6 3 4 13
Without EDTA (4b) 4 2 4 10
Group 5
Control group
With EDTA (5a) 0 0 0 0
Without EDTA (5b) 0 0 0 0
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 4 � P = 0.0411 significant
Group 1 and 5 � P = 0.00000 highly significant
Comparison between group 2 with group 1, group 3, group 4 and group 5
Group 2 and 1 � P = 0.078 not significant
Group 2 and 3 � P = 0.0031 highly significant
Group 2 and 4 � P = 0.478 not significant
52
Group 2 and 5 � P = 0.0000 highly significant
Comparison between group 3 with group 1, group 2, group 4 and group 5
Group 3 and 1 � P = 0.013 significant
Group 3 and 2 � P = 0.0031 highly significant
Group 3 and 4 � P = 0.001 highly significant
Group 3 and 5 � P = 0.784 not significant
Comparison between group 4 with group 1, group 2, group 3 and group 5
Group 4 and 1 � P = 0.0411 significant
Group 4 and 2 � P = 0.478 not significant
Group 4 and 3 � P = 0.001 highly significant
Group 4 and 5 � P = 0.0000 highly significant
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.
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