Medical

Communication

Biosci. Biotech. Res. Comm. 9(4): 725-728 (2016)

Ex vivo

comparative analysis of root-canal dentin

removal by MTwo and K3 rotary  les using spiral

computed tomography

Hengameh Akhavan

, Mehrdad Panjnoush

, Neda Montaser Kuhsari

, Azin Sadighnia

and Sohrab Tour Savadkouhi

Assistant Professor, Department of Endodontics, Dental Branch, Islamic Azad University, Tehran, Iran

Assistant Professor, Department of Oral and Maxillofacial Radiology, Dental Branch, Tehran University of

Medical Sciences, Tehran, Iran

Student of Dentistry, Dental Branch, Islamic Azad University, Tehran, Iran

Dentist

ABSTRACT

The main objective in root canal preparation is to develop an enlarged and shaped taper from apical to coronal,

maintaining the original canal shape. The aim of this study is analysis of root canals dentin removal shaped by MTwo

(Group M) and K3 (Group K) rotary  les using spiral-computed tomography. A total of 40 mesiobuccal root canals of

mesial roots with curvatures ranging 20-35 degree, and working length ranging 15-17 mm included the study. The

initial images were reconstructed and cross- sections corresponding to distance 2, 4.5 and 7mm from the anatomic

apex. Group M was prepared with Mtwo  les with master apical  le size 40 (single length technique) and group K

was prepared with K3  les (VT technique, %4), with master apical  le size 40. Post instrument images was recorded

as same as the initial ones. Dentinal thickness measured in buccal, mesial, lingual and distal sections of each root

canal. Statistical analysis was performed with one sample test Kolmogorov- Smirnov and T-test for comparing sam-

ples between groups. The mean total root dentine removal between group M (0.17+-0.04) and group K (0.20+_0.07)

was statistically different (P<0.001). Group K showed 15% more dentin removal compared group M. Recording to our

 ndings K3 had showed more dentin removal than Mtwo especially in apical and coronal third of curved root canals,

so Mtwo acted better than K3.

KEY WORDS: MTWO, K3, RESIDUAL DENTIN THICKNESS, ROOT CANAL CBCT

725

ARTICLE INFORMATION:

*Corresponding Author: s_savadkouhi@yahoo.com

Received 25

Oct, 2016

Accepted after revision 12

Dec, 2016

BBRC Print ISSN: 0974-6455

Online ISSN: 2321-4007

Thomson Reuters ISI ESC and Crossref Indexed Journal

NAAS Journal Score 2015: 3.48 Cosmos IF : 4.006

reserved.

Online Contents Available at: http//www.bbrc.in/

726

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COMPARATIVE ANALYSIS OF ROOT-CANAL DENTIN REMOVAL BIOSCIENCE BIOTECHNOLOGY RESEARCH COMMUNICATIONS

Hengameh Akhavan et al.

INTRODUCTION

The main objective in root canal preparation is to

develop an enlarged and shaped taper from apical to

coronal, maintaining the original canal shape. Shap-

ing procedure directly related not only to the length but

also to the position and curvature of each individual

root canal (Schilder, 1974). When a curvature is present,

endodontic preparations become challenging. Devia-

tion from the original curvature can lead to excessive

or inappropriate dentine removal, which weakens the

tooth, resulting in stripping perforations or fracture of

the root. Several instrument systems have been recom-

mended in the past with different features. Today, the

use of rotary Ni-Ti  les has signi cantly reduced devia-

tions from the original root canal shape compared with

stainless steel hand  les, (Kandaswamy et al 2009 Talati

et al 2013 and Stavileci et al., 2015).

Several methods have been introduced for assess-

ment of post canal instrumentation shaping such as

scanning electron microscope, radiographs, photo-

graphic assessment and computer manipulation (Hüls-

mann, Peters, & Dummer, 2005). The methods are inva-

sive in nature; hence accurate repositioning of pre- and

post-instrumented specimens is dif cult (Cumbo et al

2015).

Spiral computed tomography; a non-invasive tech-

nology has been advocated for pre-and post-instrumen-

tation evaluation of canal. It can render cross-sectional

(cut plane) and 3D images that are highly accurate and

quanti able. At any level, the amount of post instru-

mentation dentinal removal and canal transportation

can be analyzed without loss of specimen (Narayan

et al., 2012, Maitin et al., 2013 and Deepak et al., 2015).

The aim of this study is analysis of root canals dentin

removal shaped by M Two and K3 rotary  les using spi-

ral computed tomography.

MATERIAL AND METHODS

In this experimental study human extracted mandibular

 rst molars, which had no restorations and had been

extracted due to extensive destruction of coronal struc-

tures or periodontal problems subjected the study. The

teeth were disinfected in 1% hypochlorite solution for

one hour and kept in sterile normal saline solution until

further processing. Assessment radiographic images

were taken using E-speed  lms (AGFA, Heraeus Kulzer

GmbH; Hanau, Germany) with 70 kVp and 8 mA.

A total of 40 mesiobuccal root canals of mesial roots

with curvatures ranging 20-35 degree, and working

length ranging 15-17 mm were included in the study.

They were randomly divided in two experimental groups

of 18 canals each, and the remaining two for control

group. The teeth were imbedded in a self-cure acrylic

material (Acropars OP, Marlic medical industries, Tehran,

Iran) and submitted to CBCT analysis (Somatom sensa-

tion 16 CT scanner, Siemens LTD Berlin, Germany). The

initial images were reconstructed and cross- sections

corresponding to distance 2, 4.5 and 7mm from the ana-

tomic apex (Syngo CT software VB20, Siemens) (Fig.1).

The access cavities of all samples were prepared and

Initial  ling was done from 08 to 15 size k  le and both

experimental groups were instrumented with X-Smart

(Dentsply Maillefer, Ballaigues, Switzerland). Between

each instrument, the root canals were irrigated with 5

ml of 5.25% sodium hypochlorite and  nally  ushed

with normal saline. Single length technique was used in

a gentle in and outward motion according to the manu-

facturers’ instruction. Group M was prepared with Mtwo

 les with master apical  le size 40 and group K was

prepared with K3  les (VT technique, %4), with master

apical  le size 40 according to manufactures protocol.

Post instrument images was recorded as same as the ini-

tial ones. Dentinal thickness measured in buccal, mesial,

FIGURE 1. CBCT analysis (Somatom sensation 16 CT scanner, Siemens LTD Berlin,

Germany and Syngo CT software VB20, Siemens)

BIOSCIENCE BIOTECHNOLOGY RESEARCH COMMUNICATIONS

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COMPARATIVE ANALYSIS OF ROOT-CANAL DENTIN REMOVAL 727

Hengameh Akhavan et al.

lingual and distal sections of each root canal. Statistical

analysis was performed with one sample test Kolmogo-

rov- Smirnov and T-test for comparing samples between

groups.

RESULTS

No specimens excluded because of  le fracture or other

mishaps. The two specimens in control group showed

the  xing method was accurate and there was no dif-

ference between  rst and second scans. In 2mm sections

from the apices, root canal dentin removal for group

M (0.12 +- 0.20) and group K (0.14 +- 0.04) was statis-

tically different (P<0.001). Group K showed 16% more

dentin removal compared group M.In 4.5mm sections

from the apices, root canal dentin removal for group M

(0.18 +- 0.04) and group K (0.18 +- 0.04) was the same

(P<0.09).

In 7mm sections from the apices, root canal dentin

removal for group M (0.21 +- 0.01) and group K (0.27

+- 0.06) was statistically different (P<0.001). Group K

showed 27% more dentin removal compared group M

(table-1). The mean total root dentine removal between

group M (0.17+-0.04) and group K (0.20+_0.07) was sta-

tistically different (P<0.001). Group K showed 15% more

dentin removal compared group M (table-2).

DISCUSSION

NiTi rotary  les have superior shaping ability to main-

tain canal centered during instrumentation compared to

stainless steel hand  les (Gergi, Rjeily, Sader, & Naaman,

2010). But this advantage is differ among different

brands of NiTi rotary  les, depends on their speci cs.In

this study, we analyzed the effect of canal instrumenta-

tion on dentin removal using MTwo and K3 rotary  les.

The method used for dentin removal in the current study

(spiral tomography) allowed us to evaluate morphologi-

cal changes after root canal preparation in a conserva-

tive manner (Özer, 2011).

Within the limits of an “in vitro” study, the cone

beam computed tomography offers a method that is

relatively simple and economical and provides useful

information about the action of instruments in the canal

space (Gergi et al., 2010; Maitin et al., 2013; Özer, 2011;

Tasdemir, Aydemir, Inan, & Ünal, 2005). An alternative

conservative method of assessing root canal instrumen-

tation techniques is the microcomputer tomography that

is more expensive and requires well-trained operators in

order to obtain valid results (Peters et al 2001; You et al.,

2011; Zhao et al 2013).

Cumbo et al reported that M Two and BioRace

rotary  les had comparable results in amount of den-

tine removal in different levels of root canals (Cumbo et

al., 2015). For this comparison they had used specimens

with single root canals with a curvature lower than 20

degrees that is lower than our specimens (20-35 degrees).

They had used resin blocks and digital photographs for

shaping ability assessment (the Bramante technique) but

the technique they had used is not conservative com-

pared the technique had used in this study (CBCT).

In an ex vivo study by Maitin et al, they reported

the MTwo rotary  les had better well centered prepa-

ration in coronal and mid root compared to ProTaper,

K3 and Race (Maitin et al., 2013). They had used sin-

gle rooted specimens with a curvature ranging 20 to 40

degrees comparable to our specimens (20-35 degrees).

The severity of curvature makes the preparation proce-

dure more challenging. The result of our study con rms

their results and shows MTwo has little dentine removal

and better centering ability compared to K3 rotary  les.

In contrast of our results Narayan et al concluded that

MTwo rotary  les shaped root canals enlarger in volume

and with compared K3 and Race. This difference can be

explained by difference in shaping procedures (Narayan

et al., 2012).

Recording to our  ndings K3 had showed more dentin

removal than Mtwo especially in apical and coronal third

of curved root canals, so M two acted better than K3.

The authors deny any con icts of interest related to

this study.

REFERENCES

Cumb o, E., Russo, R., & Gallina, G. (2015). Assessment of Root

Canal Enlargement Using Mtwo and BioRace Rotary Files. The

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Table 1: Root dentine removal in different sections

Rotary

systems

Root

sections

Dentin removal

(mm)

Coef cient

Variations

MTwo 2mm 0.12+-0.02 17

4.5mm 0.18+-0.04 22

7mm 0.21+-0.01 5

K3 2mm 0.14+-0.04 28

4.5mm 0.18+-0.04 22

7mm 0.27+-0.06 22

Table 2: The mean total root dentine removal

Rotary

systems

Mean dentin

removal (mm)

Coef cient

Variations

MTwo 0.17+-0.04 23

K3 0.20+-0.07 35

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