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 Table of Contents  
ORIGINAL ARTICLE
Year : 2016  |  Volume : 6  |  Issue : 2  |  Page : 61-67

Shaping ability of different endodontic single-file systems using simulated resin blocks


1 Department of Conservative Dentistry, Duhok University, Duhok, Iraq
2 Department of Restorative Dentistry, Faculty of Dentistry, Ajman University of Science and Technology, Ajman, United Arab Emirates

Date of Web Publication6-Jan-2017

Correspondence Address:
Abdul Rahman Mohammed Saleh
Department of Restorative Dentistry, Faculty of Dentistry, Ajman University of Science and Technology, P.O. Box 346, Ajman
United Arab Emirates
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2229-6360.197745

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  Abstract 

Objectives: The aim of this study was to compare the shaping ability of four different single-file systems; WaveOne (Dentsply Maillefer, Ballaigues, Switzerland), Reciproc (VDW), OneShape (Micro Mega), and F360 (Komet Brasseler, Lemgo, Germany). Stainless steel K-file (KSS) (Dentsply Maillefer, Ballaigues, Switzerland) was used as a control during the preparation of simulated root canals.
Materials and Methods: Eighty L-shaped canals in resin blocks were prepared to an apical size of 25 using one of the five groups (each group = 16). A series of pre- and post-operative images were taken by a digital camera (EOS 650D. Canon) and superimposed on two different layers. The amount of resin removed from both the inner and the outer sides of the canal were measured at five different points: orifice, half way of the orifice, beginning of the curvature, apex of the curve, and the apical end. The amount of resin removed by each system was measured using image analysis software. Canal aberrations and the preparation time were also recorded. The data were statistically analyzed by using analysis of variance, Tukey's post hoc, and Chi-square tests.
Results: There are significant differences between all single files and KSS in time for preparation (P < 0.05) while there is no significant difference between all single nickel-titanium (NiTi) files. No instrument is fractured during canal preparation. More canal aberrations were reported with hand K-files in which there is a highly significant difference compared with other single-file systems. OneShape file reported fewer canal aberrations, but all OneShape files deformed after use. There are significant differences between single NiTi files and KSSs in preserving the canal curvature while there is no significant difference between all single NiTi files. Reciproc and WaveOne files removed significantly greater amounts of resin from the inner side at the beginning and apex of the curve (P < 0.05). Canals prepared with the F360 and OneShape systems were better centered compared with the Reciproc and WaveOne systems.
Conclusion: Within the limitation of this study, NiTi instruments are superior to stainless steel K-files in their shaping ability. All single-file systems maintained root canal curvature well and were safe to use. Canals prepared with the F360 and OneShape systems were better centered compared with the Reciproc and WaveOne systems.

Keywords: Reciprocation; shaping ability; simulated canals; single file


How to cite this article:
Rashid AA, Saleh AM. Shaping ability of different endodontic single-file systems using simulated resin blocks. Indian J Multidiscip Dent 2016;6:61-7

How to cite this URL:
Rashid AA, Saleh AM. Shaping ability of different endodontic single-file systems using simulated resin blocks. Indian J Multidiscip Dent [serial online] 2016 [cited 2017 May 26];6:61-7. Available from: http://www.ijmdent.com/text.asp?2016/6/2/61/197745


  Introduction Top


Disinfection of the root canal by instrumentation and irrigation is regarded as the most crucial factor in the treatment and prevention of endodontic diseases. In daily clinical practice, instrumentation of the root canal system is usually the most time consuming and the technically demanding element of the treatment. [1] The introduction of nickel-titanium (NiTi) instruments into endodontic practice has greatly enhanced the root canal shaping and decreased the time required for mechanical preparation. [2]

The use of the NiTi rotary instrumentation has made endodontic practice easier and faster than hand instrumentation, the shaping of curved canals has become more predictable, reducing operator fatigue and the time required to complete the preparation. [3]

Moreover, an increasing number of NiTi rotary systems have been marketed by various manufacturers. These systems differ from one another in the design of cutting blades, body taper, and configuration of the file tip. Despite the purported clinical advantages of the rotary techniques, unexpected instrument fracture is not uncommon, especially for less-experienced operators. [4]

Currently, two different concepts of single-file systems are used as follows:

  1. Reciproc (VDW, Munich, Germany) and WaveOne (Dentsply Maillefer, Ballaigues, Switzerland). These instruments are used in a reciprocal motion, made of M-wire technology. The reciprocating working motion consists of counterclockwise (cutting direction) and clockwise motions
  2. Another concept of single-file instrumentation is that a single instrument is to be used in the full clockwise rotation using conventional NiTi alloy. OneShape (Micro Mega, Besancon, France) and F360 (Komet Brasseler, Lemgo, Germany) belong to this group of single-file systems.


The shaping ability of these single-file systems has been compared with full-sequence rotary systems both in extracted teeth and resin blocks with encouraging results. Saleh et al. [5] compared the shaping ability of four different single-file systems in simulated S-shaped canals. WaveOne, Reciproc, OneShape, and F360 were used. S-shaped canals in resin blocks were prepared to an apical size of 25. They concluded that all single-file instruments were safe to use and were able to prepare the canals efficiently. However, single-file systems that are less tapered seem to be more favorable when preparing S-shaped canals. In a study by Bürklein et al. [6] using extracted teeth, Reciproc and WaveOne prepared severely curved canals significantly faster than full-sequence systems, with no difference regarding the maintenance of the original canal curvature. However, only sparse information is currently available regarding the shaping ability of these single-file systems together when used in L-shaped canals.


  Materials and Methods Top


Simulated canals

Eighty simulated L-shaped canals (Endo Training Block-L; Dentsply Maillefer, Ballaigues, Switzerland) with a taper of 0.02, an apical diameter of 0.15 mm, and length of 16 mm were used in this study.

Preoperative imaging

A preinstrumentation image of each simulated canal was recorded by the digital camera (EOS 650D. Canon). To take standardized and reproducible pictures, a camera stand was used, and the camera was positioned centrally and at 90° to the specimen, placed at a fixed distance from the block on a custom-made template to ensure placement of the block in a fixed place under camera lens in mesiodistal view. Three landmarks were made with a permanent pen in the resin block from the side wall to the near inner and outer curve of the canal without penetrating into the canal. Each simulated canal will be colored with black ink injected with a syringe. Preinstrumentation images of all resin blocks were obtained and saved as JPEG format files.

Sample distribution

The sample size calculation was based on the difference between means obtained from a pilot study and was performed at the 95% level of confidence and 80% statistical power. The calculation indicated that 16 simulated resin block per group would be necessary.

The patency of the canals was confirmed by passing a size 10 K-file just beyond the apex; subsequently, the resin blocks were randomly divided into five groups (n = 16 canals/group) and were numbered according to the type of file used to prepare the canals.

The canals were instrumented using four experimental single-file systems while the hand K-files step-back preparation was used as a control group. The simulated canals were instrumented to the full working length as follows:

  • Group 1: The WaveOne primary file (tip size, 25; apical taper, 0.08) was used in a programed reciprocating motion generated by the X Smartplus motor (Dentsply Maillefer, Ballaigues, Switzerland) in "WAVEONE ALL" mode. The files were used in a pecking motion (amplitude <3 mm, three pecks) according to manufacturer's instructions. The flutes of the instrument were cleaned after three in-and-out-movements (pecks)
  • Group 2: The R25 Reciproc file (tip size, 25; apical taper, 0.08) was used in a programed reciprocating motion generated by the X Smartplus motor in "RECIPROC ALL" mode. The files were used in a pecking motion (amplitude < 3 mm, three pecks) according to the manufacturer's instructions. The flutes of the instrument were cleaned after three in-and-out-movements (pecks)
  • Group 3: The OneShape file (tip size, 25; taper, 0.06) was used in full clockwise rotation with a rotational speed of 400 rpm generated by the X-Smartplus motor, and the torque was adjusted to 4 Ncm. The files were used in a slight pecking motion according to the manufacturer's instructions
  • Group 4: The F360 file (tip size, 25; taper, 0.04) was used in full clockwise rotation with a rotational speed of 300 rpm generated by the X-Smartplus motor, and the torque was adjusted to 1.8 Ncm. The files were used in a slight pecking motion according to the manufacturer's instructions
  • Group 5: In this control group, simulated root canal was prepared using stainless steel K-files (KSSs) (Dentsply Maillefer, Ballaigues, Switzerland) hand instrumentation using step-back preparation technique. The shaping procedure started with 15/.02, 20/.02/, and 25/.02 to the full working length and then step-back continuous with 30/.02 (W.L-1), 25/.02 (W.L), 35/.02 (W.L-2), 25/.02 (W.L), 40/.02 (W.L-3), 25/.02 (W.L), 45/.02 (W.L-4), 25/.02 (W.L), 50/.02 (W.L-5), 25/.02 (W.L). 55/.02 (W.L-6), 25/.02 (W.L), 60/.02 (W.L-7), and 25/.02 (W.L).


A new instrument was used to prepare four canals in all groups according to the previous studies. [7] Glyde-Prep (Dentsply Maillefer, Ballaigues, Switzerland) was used as a lubricant before the utilization of each instrument and distilled water was used for irrigation during preparation. All canals were prepared by one experienced operator. Measurement of the canals was carried out by a second examiner who is unaware of the experimental groups. A randomly laid down sequence was used to avoid bias toward one of the fifth instrumentation groups.

Assessment of canal preparation

A postoperative image of each sample was taken under the same conditions used in taking the preoperative image after injecting the block with red ink. The pre- and post-operative images were superimposed using image software (Adobe Photoshop Elements 7.0, Adobe Systems Incorporated, San Jose, CA, USA). The composite image was assessed using a computer program Image J 1.48v software (Wayne Rasband, National Institutes of Health, USA).

Preparation time

The time for canal preparation, which included total active instrumentation, cleaning of the flutes of the instruments, and irrigation, was recorded.

Canal aberrations assessment

Each composite image was assessed for the presence of canal aberrations including zip and elbow, ledges, perforation, danger zone, and outer widening, according to al-Omari et al., 1992, [8] and al-Omari et al., 1992. [9]

Width measurements

Superimposed image using Adobe Photoshop detailed the outline of the original canal preoperative and the outline of the canal postoperative images; it was possible to quantify the amount of the resin material removed by measuring the difference in width between the two images. Measurements were taken at fixed measurement position in L-shaped canal including the width of the resin removed from the outer and inner aspects of the curve of the original canal.

The resin removal calculated at five different points using Alodeh and Dummer methods is described below. [10] The inner and outer width is taken perpendicularly to the long axis of the canal for L-shaped canal:

  • Position 1: 5 mm from the orifice
  • Position 2: Half-way from the beginning of the curve to the orifice (7 mm from orifice)
  • Position 3: The beginning of the curve. The point where the canal starts to deviate from the long axis of the straight part of the canal
  • Position 4: Apex of the curve. This was determined by the intersection of two lines; one drawn along the outer border of the straight part of the canal and the second drawn along the outer border of the apical aspect of the canal
  • Position 5: Apical end, this represents the end point of the preparation.


Statistical analysis

Statistical evaluations were performed with SPSS software (IBM SPSS Statistics 21, SPSS Inc., Chicago, USA). The normality of the data was verified for each set of measurements by using Kolmogorov-Smirnov test. The results of width measurements were statistically analyzed using one-way analysis of variance (ANOVA) and the post hoc Tukey's test. ANOVA and the post hoc Tukey's test were also used to analyze the preparation times, and Chi-square test was used to analyze the incidence of canal aberrations. The significance level was set at P < 0.05.


  Results Top


Preparation time

The mean and standard deviations for the time required to prepare the simulated resin blocks by the different file systems are shown in [Table 1].{Table 1}

The statistical analysis shows that there is a highly significant difference among all the single-file systems compared to the hand K-file while there is no statistically significant difference between the WaveOne, Reciproc, OneShape, and F360 file systems.

Incidence of canal aberration

Regarding the incidence of canal aberration, the results [Table 2] show that more aberrations were reported with hand K-files in which there is a highly significant difference compared with other single-file systems in the formation of apical zip, elbow, danger zone, and ledge occurrence. OneShape file reported no canal aberrations except danger zone as reported in two samples. The incidence of danger zone was reported more in canals prepared with WaveOne and Reciproc files than canals prepared with F360 and OneShape files.{Table 2}

Width measurements

Inner width measurements


There were statistically significant differences in the mean values of inner width of material removal between WaveOne system and Reciproc system, OneShape, and F360 systems at all points except the apex of curve and apical end, and there were statistically significant differences in the mean values of inner width of material removal between WaveOne system and hand K-files system at all measuring points, except apical end.

There were statistically significant differences in the mean values of the inner width of material removal between Reciproc system and OneShape system at all points except orifice and the apical end.

There were statistically significant differences in the mean values of the inner width of material removal between F360 and OneShape systems at all points except apex of the curve and the apical end.

Outer width measurements

There were statistically significant differences in the mean values of outer width of material removal between WaveOne system and Reciproc system only at the beginning of curve, there were statistically significant differences in the mean values of outer width of material removal between WaveOne system and OneShape system only at the apex of curve, there were statistically significant differences in the mean values of outer width of material removal between WaveOne system and F360 at all points except apical end, and there were statistically significant differences in the mean values of outer width of material removal between WaveOne system and hand K-file at all points.

There were statistically significant differences in the mean values of the outer width of material removal between Reciproc system and OneShape system only at the beginning of the curve and apex of the curve. There were statistically significant differences in the mean values of the outer width of material removal between Reciproc system and F360 system only at the orifice, and there were statistically significant differences in the mean values of the outer width of material removal between Reciproc system and hand K-file at all points except half of the orifice.

There were statistically significant differences in the mean values of the outer width of material removal between OneShape system and F360 system only at all points except the apical end, and there were statistically significant differences in the mean values of the outer width of material removal between OneShape system and hand K-file at all points except half of the orifice.

There were statistically significant differences in the mean values of the outer width of material removal between F360 system and hand K-file only at all points except half of the orifice and the apical end [Table 3].{Table 3}


  Discussion Top


This study aimed to compare the efficiency and shaping ability of the four single-file systems, i.e. WaveOne, Reciproc, OneShape, and F360. WaveOne and Reciproc systems are designed specifically to be used in reciprocating motion, while OneShape and F360 systems are designed to be used in continuous rotation.

Simulated root canals are made out of resin and have a central canal with a fixed curvature and diameter. When used in studies to compare different file systems, the simulated canal can help to standardize the canal dimensions to be prepared and the amount of stress placed on the file. The use of a resin also allows the hardness to be standardized, whereas in a tooth, the hardness of dentine can vary dramatically. [11]

All groups of single-file systems with size 25 apical diameter were used in this investigation. These instruments had the same tip size of 25. This was achieved by the recommendation of the manufacturers as these sizes are designated for narrow and curved canals when hand instruments do not passively reach the full working length. Moreover, OneShape system is only available with this tip size while size 25 K file is selected to be the master apical file for hand instrument group.

It should be taken into consideration that the taper of the instruments used was different. The final taper was 0.08 at the apical 3 mm for Reciproc and WaveOne systems, 0.06 for OneShape system, and 0.04 for F360 system.

Preparation time

Preparation time is dependent on the technique and the number of instruments used, the operator experience, and on further details of the study design. [11] In this study, the preparation time involved active instrumentation as well as the time required for shifting files, cleaning the flutes of the files, and irrigation to allow comparison of the results with those of previous studies conducted with an identical experimental setup. [6],[12]

The K-file hand instruments as used in this investigation required ten instruments to prepare the root canal to a size of 25 while only one instrument was used for WaveOne, Reciproc, OneShape, and F360 systems. All single-file systems were significantly faster than K-file hand instruments (P
< 0.05), while there are no significant differences in preparation time for all single-file systems such as Waveone, Reciproc, OneShape, and F360. Other studies that investigated the shaping ability of different single-file systems in extracted teeth and simulated S-shaped canal [5],[6] found some differences in speed between single-file systems.

Canal aberration

Regarding the incidence of canal aberration, results of this study show that more aberrations were reported with hand K-files in which there is a highly significant difference compared with other single-file systems in the formation of apical zip, elbow, danger zone, and ledge occurrence. This is clearly due to the stiffness of the stainless steel (SS) instrument materials and multiple instruments used to prepare the canal.

OneShape file reported no canal aberrations except danger zone as reported in two samples; this is due to the design of the instrument which is in the tip region, the cross-sectional design represents three symmetrical cutting edges, while in the middle of the working part, the cross-sectional design progressively changes from an asymmetrical three-cutting edge design to two cutting edges. At the coronal part, the S-shaped cross-sectional design shows two symmetrical cutting edges, resembling the cross-sectional design of Reciproc and F360 instruments. The incidence of danger zone was reported more in canals prepared with WaveOne and Reciproc systems than canals prepared with F360 and OneShape systems, and this may be due to the reciprocating motion of these two instruments. These results are in agreement with the results of Saleh et al. [5]

Width measurement

Measurements were determined at certain different points. The width at the orifice, halfway between the curve and the orifice, width at the beginning of the curve, width at the apex of the curve of the original canal, and width at the end point.

At the beginning of the curve point, all systems cut more in the inner wall than outer and there is significant difference between single-file systems and KSS. WaveOne and Reciproc systems show more cuts in the inner wall than OneShape and F360 systems, so these instruments should be used cautiously to avoid excessive removal at the inner curve, leading to danger zones and straightening of the canal. The results obtained for the Reciproc system are consistent with those of a previous study by Yoo and Cho [13] who suggested careful preparation of severely curved canals with Reciproc to avoid danger zone formation. However, the results obtained with the WaveOne system are not consistent with another study in which good shaping effects were obtained when this instrument was used to prepare both L- and S-shaped simulated canals. [13]

At the apex of curve point, all systems cut in the inner surface more than the outer except OneShape which shows more canal preservation than other systems at this point. In the apex region, all systems cut more at the outer wall than the inner and there is a significant difference between all single NiTi files and KSS files. OneShape system shows more canal preservation at this point.

This study found that SS instrument led to more resin removal at the middle level (curved region) and the outer wall at the apex region than NiTi instruments. This result indicates that NiTi instruments decreased the risk of strip perforation in the curved canals. SS hand file has a high frequency of preparation errors, probably as a result of the inherent stiffness of the metal. In most circumstances, the use of SS files in narrow curved canals is difficult and cause preparation errors at apex, thus hindering obturation. [14]

This study showed that the F360 file system with a constant of 0.04 taper removes less resin than OneShape file system of a constant of 0.06 taper, and OneShape less than Waveone and Reciproc respectively (0.08 taper at the apical 3 mm followed by a regressive taper). These differences were clearly due to differences in their taper. Despite WaveOne and Reciproc instruments having similarities (same alloy, reciprocation movement, and tip size), their different cross-sectional designs may explain these results. Reciproc has a double-cutting edge S-shaped geometry, whereas WaveOne has a modified, convex, triangular cross section with radial lands at the tip and a convex triangular cross section in the middle and coronal portion of the instrument. This result is in agreement with that of Capar et al. [15]

During the present study, no instrument fractured, there are no signs of bending or distortion in all file systems except files of OneShape system. This finding is in agreement with the findings of Saber et al. [7] All instruments were used to enlarge four curved canals. Thus, in this laboratory study, these files could be used to enlarge at least four canals using the instrumentation sequence described in the present study without an increased risk of fracture.

F360 instrument showed no signs of distortion compared to OneShape instruments which may be due to the less tapering (0.04). From a clinical perspective, the obtained differences might be of subordinate importance.

The main findings of the present study were that less tapered instruments caused less canal transportation compared with more tapered single-file instruments and that the taper of the instruments is the predetermining factor regarding the shaping ability of the tested instruments in the L-shaped canal. This finding is consistent with the findings of Saleh et al. [5]


  Conclusion Top


Within the limitation of this present study, all single-file systems are superior to stainless steel K-files in their shaping ability. All single-file systems maintained root canal curvature well and were safe. They preserved the shape of L-shaped canals by gradually decreasing the amount of resin material removed from the orifice towards the apical end produced a continuous tapering funnel shaped, with less canal aberration. There is no statistically significant difference between the WaveOne, Reciproc, OneShape, and F360 systems for the time required to prepare the canal. Canals prepared with the F360 and OneShape systems were better centered compared with the Reciproc and WaveOne systems. OneShape file reported less canal aberration than other single file systems.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

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Haapasalo M, Endal U, Zandi H, Coil J. Eradication of endodontic infection by instrumentation and irrigation solutions. Endod Top 2005;10:72-102.  Back to cited text no. 1
    
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Thompson SA, Dummer PM. Shaping ability of Lightspeed rotary nickel-titanium instruments in simulated root canals. Part 1. J Endod 1997;23:698-702.  Back to cited text no. 3
    
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Yared G, Bou Dagher F, Kulkarni K. Influence of torque control motors and the operator's proficiency on ProTaper failures. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2003;96:229-33.  Back to cited text no. 4
    
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Saleh AM, Vakili Gilani P, Tavanafar S, Schäfer E. Shaping ability of 4 different single-file systems in simulated S-shaped canals. J Endod 2015;41:548-52.  Back to cited text no. 5
    
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Bürklein S, Hinschitza K, Dammaschke T, Schäfer E. Shaping ability and cleaning effectiveness of two single-file systems in severely curved root canals of extracted teeth: Reciproc and WaveOne versus Mtwo and ProTaper. Int Endod J 2012;45:449-61.  Back to cited text no. 6
    
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Saber SE, Nagy MM, Schäfer E. Comparative evaluation of the shaping ability of WaveOne, Reciproc and OneShape single-file systems in severely curved root canals of extracted teeth. Int Endod J 2015;48:109-14.  Back to cited text no. 7
    
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al-Omari MA, Dummer PM, Newcombe RG. Comparison of six files to prepare simulated root canals 1. Int Endod J 1992;25:57-66.  Back to cited text no. 8
    
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al-Omari MA, Dummer PM, Newcombe RG, Doller R. Comparison of six files to prepare simulated root canals 2. Int Endod J 1992;25:67-81.  Back to cited text no. 9
    
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Alodeh MH, Dummer PM. A comparison of the ability of K-files and Hedstrom files to shape simulated root canals in resin blocks. Int Endod J 1989;22:226-35.  Back to cited text no. 10
    
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Hülsmann M, Peters OA, Dummer Paul MH. Mechanical preparation of root canals: Shaping goals, techniques, and means. Endod Top 2005;10:30-76.  Back to cited text no. 11
    
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Schäfer E, Erler M, Dammaschke T. Comparative study on the shaping ability and cleaning efficiency of rotary Mtwo instruments. Part 2. Cleaning effectiveness and shaping ability in severely curved root canals of extracted teeth. Int Endod J 2006;39:203-12.  Back to cited text no. 12
    
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Yoo YS, Cho YB. A comparison of the shaping ability of reciprocating NiTi instruments in simulated curved canals. Restor Dent Endod 2012;37:220-7.  Back to cited text no. 13
    
14.
Schäfer E, Tepel J, Hoppe W. Properties of endodontic hand instruments used in rotary motion. Part 2. Instrumentation of curved canals. J Endod 1995;21:493-7.  Back to cited text no. 14
    
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Capar ID, Ertas H, Ok E, Arslan H, Ertas ET. Comparative study of different novel nickel-titanium rotary systems for root canal preparation in severely curved root canals. J Endod 2014;40:852-6.  Back to cited text no. 15
    




 

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