Saudi Endodontic Journal

ORIGINAL ARTICLE
Year
: 2019  |  Volume : 9  |  Issue : 1  |  Page : 21--26

Comparative evaluation of shaping ability of rotary and reciprocating nickel-titanium single file instruments on simulated root canals


Arvind Kumar, A Sheerin Sarthaj 
 Department of Conservative Dentistry and Endodontics, Rajas Dental College and Hospital, The Tamil Nadu Dr. MGR Medical University, Tirunelveli, Tamil Nadu, India

Correspondence Address:
Dr. A Sheerin Sarthaj
Department of Conservative Dentistry and Endodontics, Rajas Dental College and Hospital, The Tamil Nadu Dr. MGR Medical University, Tirunelveli, Tamil Nadu
India

Abstract

Introduction: Effective cleaning of the root canal system is the primary objective of rotary instrumentation. For three-dimensional obturation of the root canal system, ideal preparation should have a continuously tapering funnel shape from the orifice to the apex. The study aimed to evaluate the shaping ability of two rotary and two reciprocating nickel-titanium (NiTi) single-file instruments on simulated root canals using image analysis software. Materials and Methods: Forty resin blocks with simulated canals of 30° curvature were divided into four experimental groups containing ten samples in each group. The canals were prepared using Reciproc (VDW, Munich, Germany), WaveOne (Dentsply, Maillefer, Ballaigues, Switzerland), OneShape (Micro-Mega, Besancon, France), and F360 (Komet, Brasseler, Lemgo, Germany) size 25 NiTi systems using X Smart Plus (Dentsply). Pre- and post-preparation canals were photographed in a standardized manner and were superimposed. The inner and outer walls of canal curvature were evaluated to determine the most significant change using the image analysis software. Results: The amount of resin removed from the inner walls was less with rotary single-file NiTi systems when compared with reciprocating. Preparation time was less with rotary instruments. No instrument separation was noted. All instrument systems maintained the original canal curvature. Conclusion: Rotary single-file systems maintained the canal curvature better than reciprocating single-file systems.



How to cite this article:
Kumar A, Sarthaj A S. Comparative evaluation of shaping ability of rotary and reciprocating nickel-titanium single file instruments on simulated root canals.Saudi Endod J 2019;9:21-26


How to cite this URL:
Kumar A, Sarthaj A S. Comparative evaluation of shaping ability of rotary and reciprocating nickel-titanium single file instruments on simulated root canals. Saudi Endod J [serial online] 2019 [cited 2019 Feb 21 ];9:21-26
Available from: http://www.saudiendodj.com/text.asp?2019/9/1/21/249592


Full Text

 Introduction



Endodontic mishaps in the form of canal transportation, ledges and perforations occur partly because of inattention to minute details; however, the most of which is related to metal technology.[1] Root canal preparation is performed with files, reamers, burs, sonic instruments or mechanical apparatus and with nickel-titanium (NiTi) rotary files systems. Since most hand preparation techniques are time-consuming and may lead to iatrogenic errors,[2] much attention is directed toward root canal preparation techniques with NiTi rotary instruments. Numerous studies have reported that they could efficiently create smooth, predetermined funnel-form shapes, with minimal risk of ledging and transportation.[3],[4],[5] They also reduce operator fatigue and the time required to complete the preparation.[5] Even though NiTi instruments are known for their superelasticity and shape memory, they have by tensile-compressive forces.[6] The tensile-compressive forces are higher in the curved compared to the straight canals.

Yared[7] a pioneer in the field of reciprocating file systems put forth the balanced force technique. The reciprocating files move both in a counterclockwise and clockwise rotation. The counterclockwise rotation has a cutting action whereas the clockwise has a releasing operation. The metallurgy of reciprocating files is from M wire technology to the recently introduced gold wire technology with WaveOne gold files. This unequal reciprocating movement prevents taper lock and instrument separation.[7],[8],[9] The purpose of this study was to assess the morphological characteristics of prepared simulated curved canals by the use of four NiTi systems, two rotary, and two reciprocating. The shaping ability was evaluated by the amount of resin removed during instrumentation and also avoidance of iatrogenic errors.

 Materials and Methods



A total of 40 simulated canals with 30° curvature in transparent resin blocks (Endo training blocks, Nissin) were used in this study. Ethical Committee approval was obtained from Rajas Dental College & Hospital. The ethical committee approval number is RDCH/EC/03/2016. Since we used a curved canal morphology to analyze the shaping ability in this study the curved portion of the canal was 6 mm, and the straight part was 13 mm. The instrumentation was done using X Smart IQ Endomotor (Dentsply Maillefer). The endodontic training blocks were divided into four groups (OneShape, F360, WaveOne and Reciproc groups and preinstrumentation photographs of the canals were taken in a standardized manner using a digital camera [Figure 1].{Figure 1}

The standardization achieved by making an elastomeric impression on the base former and a transparent resin block was placed in the center of the impression before it sets to mark a template for the subsequent placement of blocks. The camera was mounted at an angle from the flat surface where the resin blocks were placed and the all the preoperative photographs were made from the same angulation and the same place of placement of resin blocks.

The canal preparation[10] was begun by checking the patency of the simulated canals with a 10K size file. The working length was kept 0.5 mm short of the apex. The irrigant that was used to remove the debris was distilled water. The instrumentation sequences were as follows:

Group 1

OneShape rotary single-file system (n = 10). The specifications of this file system include 25/0.06, speed 400 rpm, and torque 4Ncm. The files were used in a reaming motion. The motor that was used was X-Smartplus motor.

Group 2

F360 rotary single-file system (n = 10). The specifications of this file system include 25/0.04, speed 300 rpm and torque 1.8 N cm. The files were used in a reaming motion. The motor used was X-Smartplus motor.

Group 3

WaveOne primary reciprocating single-file system (n = 10) with the tip size, 25; apical taper, 0.08 was used in a programmed reciprocating motion generated by the X Smartplus motor (Dentsply Maillefer, Ballaigues, Switzerland). The files were used in an in and out pecking motion. With each pecking motion, the instrument advanced 3 mm into the canal. The debris accumulated in the flutes was removed using dampened cotton after three consecutive pecking motions.

Group 4

Reciproc reciprocating single-file system (n = 10) with the tip size, 25; apical taper, 0.08 was used in a programmed reciprocating motion generated by the X Smartplus motor. The files were used in an in and out pecking motion. With each pecking motion, the instrument advanced 3 mm into the canal. The debris accumulated in the flutes was removed using dampened cotton after three consecutive pecking motions.

One operator performed all the preparations.

Concerning the previous studies, for every four canals, a new instrument was used.[9] During the cleaning and shaping of the root canal system, Glyde-Prep (Dentsply Maillefer, Ballaigues, Switzerland) was used as a lubricant and Ballaigues, Switzerland) was used as a lubricant and distilled water was used for irrigation. After the root canal preparation using the respective File Systems, postoperative images were made under the same experimental conditions. The superimposition of images was done on digital software (Adobe Photoshop Elements 7.0, Adobe Systems Incorporated, San Jose, CA, USA). The composite image was assessed using an Image Analysis Software. The time taken for canal preparation, which included total active instrumentation, cleaning of the flutes of the instruments, and irrigation, was recorded. The presence of various canal aberrations including zipping and elbow, ledges, perforation, danger zone, and outer widening was also recorded.[11]

The shaping ability was assessed by the amount of resin that was removed during canal preparation. Measurements were taken at fixed measurement positions that are 0–3 mm, 3–6 mm, and 6–9 mm. The width of the resin removed from the outer and inner aspects of the curve of the original canal was calculated, and the data were recorded.

The superimposed images are shown in [Figure 2]:{Figure 2}

Statistical analysis

Statistical evaluations were performed with SPSS 21 software (IBM SPSS Statistics 16, SPSS Inc., Chicago, USA). The statistical tests employed include ANOVA and post hoc Tukey's test for both the shaping ability as well as the preparation times. The significance level was set at (P < 0.05).

 Results



The mean and standard deviation of the proportion of resin removed from the inner walls of the canal are tabulated in [Table 1].{Table 1}

The graphical representation of the above results is summarized in [Graph 1].[INLINE:1]

There were statistically significant differences in the mean values of the inner width of material removal between Reciproc system, OneShape system, F360, and WaveOne system at all the three levels, with the Reciproc file system bearing the highest mean value of all the file systems used in the study.

The mean and standard deviation of the proportion of resin removed from the outer walls of the canal are tabulated in [Table 2].{Table 2}

The graphical representation of the above results is summarized in [Graph 2].[INLINE:2]

There were statistically significant differences in the mean values of the outer width of material removal between Reciproc system, OneShape system, F360, and WaveOne system at all the three levels, with the Reciproc file system bearing the highest mean value of all the file systems used in the study.

The statistically significant results are summarized in [Table 3].{Table 3}

Preparation time

The preparation time included the preparation time, the cleaning time and the irrigation time which was recorded, and the results are tabulated as in [Table 4].{Table 4}

There were significant differences noted among all the groups, and both the reciprocating file systems, Reciproc and WaveOne took comparatively higher preparation time than compared with the rotary single file systems, OneShape, and F360.

The incidence of canal ABERRATIONS

The iatrogenic error such as canal aberration was more with Reciproc file system as summarized in [Table 5].{Table 5}

 Discussion



Four different file systems, namely two rotary OneShape, and F360 and two reciprocating WaveOne and Reciproc were used in this study to evaluate their shaping ability.

The parameters and methodology employed in this study are all standardized.

Resin blocks

Resin blocks were used in this study for standardization even though their hardness differs considerably than that of dentin.[12]

File systems

All groups of single-file system with size 25 apical diameter were used in this study. The metallurgy of the files included is NiTi for rotary single file systems and M-wire technology for reciprocating file systems. The taper differed considerably, 0.08 for Reciproc and WaveOne 0.06 for WaveOne and 0.04 for F360 systems. The cross-sectional design of the files too plays a significant role in the results of the study. First, F360 and OneShape share the same S-shaped cross-section, which has a considerable cutting ability. Second, the reciprocating and higher flexibility wire of Reciproc and WaveOne resulted in more resin removal in the coronal portions of the canal due to the double S-shaped and the convex triangular cross-section of the WaveOne reciprocating files. The results of the study may be related to the movement, cross-sectional design, and thread pitch of instruments. The results of this study were concomitant with those of the survey conducted by Abu Haimed et al.[10] and they are contradictory to the study by Aminsobhani et al.[13]

Preparation time

The preparation time included the preparation time, the cleaning time, and the irrigation time.[14],[15] Shaping with single-instrumentation takes less time compared to the multiple file systems. In a similar study comparing the shaping efficacy of Reciproc and WaveOne versus ProTaper, Schafer et al.[15] described a significant 60% decrease in shaping time. Even though there is a significant reduction in the overall preparation time, the preparation time for reciprocating files was considerably higher. This may be due to the increased time required for cleaning of the flutes which augured more debris coronally.

Canal aberrations

Even though this study analyzed different types of aberrations, the Reciproc file system depicted more number of danger zones than compared to the other three file systems which may be attributed to its reciprocating movement[16] and cutting tip.

Width measurement

The shaping ability evaluation was done in three different areas, namely 0–3 mm, 3–6 mm, and 6–9 mm, since these areas are more critical in root canal preparations. 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[17] which 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 the manufacturer's recommendations that they can be efficiently used in L-and S-shaped canals.

The single rotary file systems used in this study have varying tapers, namely 0.04 for F360 and 0.06 for OneShape. However, the reciprocating file systems have a taper of 8%. Hence, the canal shaping ability can be related to the differences in the taper in rotary single file systems.[18] However, the differences in reciprocating single file systems may be due to the cross-sectional designs. The cross sections of Reciproc and WaveOne, respectively, are a double-cutting edge S-shaped geometry and modified, convex, triangular cross-section at the tip, and a convex triangular cross-section after that.

Since each file was discarded after instrumenting four canals, there was no distortion or file separation. The findings that were distinctive of this study were related to the taper. Lesser the taper, more accurate is the shaping ability.

 Conclusion



Within the limitations of this study, rotary single-file systems prepared narrow canals with less foramen transportation, and with less preparation time, whereas reciprocating single-file systems prepared wider canals with canal straightening and require more preparation time.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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