| Abstract|| |
Aim: The aim of the study was to evaluate the canal transportation and centering ability of rotary and reciprocating file systems using cone-beam computed tomography.
Materials and Methods: Mesiobuccal canals of sixty mandibular molars were selected for the study. Canals of length 19 mm, curvature of 10°–12°, and uncalcified with fully formed apex were selected. Canals were randomly divided into three groups of 20 teeth, and canal preparation with the WaveOne Gold, TruNatomy, and One Curve systems was performed according to the manufacturers' instructions. Cone-beam computed tomographic images were taken before and after instrumentation in the same position for comparative analysis.
Statistical Analysis Used: Apical transportation was calculated at the distances of 2, 3, and 4 mm from the apex. Tukey's post hoc test and unpaired “t”-tests were used to statistically analyze the data.
Results: WaveOne Gold caused less canal transportation and better-centering ability than TruNatomy and One Curve at all the three levels; there was a significant difference in canal transportation and centering ability among all the groups as well as all the three levels, i.e., 2, 3, and 4 mm from the apex.
Conclusion: WaveOne Gold (Reciprocating) reported less canal transportation and better-centering ability than rotary instruments TruNatomy and One Curve (Rotary) at all the three levels.
Keywords: Canal transportation; centering ability; reciprocating; rotary
|How to cite this article:|
Singh T, Kumari M, Kochhar R. Comparative evaluation of canal transportation and centering ability of rotary and reciprocating file systems using cone-beam computed tomography: An in vitro study. J Conserv Dent 2023;26:332-7
|How to cite this URL:|
Singh T, Kumari M, Kochhar R. Comparative evaluation of canal transportation and centering ability of rotary and reciprocating file systems using cone-beam computed tomography: An in vitro study. J Conserv Dent [serial online] 2023 [cited 2023 Oct 1];26:332-7. Available from: https://www.jcd.org.in/text.asp?2023/26/3/332/376901
| Introduction|| |
Root canal instrumentation is an important step in endodontic therapy that aims to remove pulp canal tissues, reduce the microbial count, allow irrigant penetration, and provide a convenient shape for root canal filling procedures.
Transportation of the canal may occur as a result of the instruments' lack of flexibility and centering ability, or as a result of the instrumentation technique used. With the introduction of rotary nickel–titanium (NiTi) instruments into modern endodontics, canal preparation can now be completed with fewer procedural errors.
Following the advances in NiTi technology, WaveOne Gold (Dentsply Sirona) instruments are built using a postmanufacturing thermal process that results in a file with superelastic NiTi metal properties.
TruNatomy is a new generation of rotary files with slim NiTi wire design 0.8 mm maximum flute diameter (system Dentsply Sirona). The instrument is made of special NiTi heat-treated wire that provides greater flexibility, allowing the file to be prebent when necessary, and has superior canal-centering ability.
One Curve, the Endo DNA (MicroMega) single-file system made from heat-treated NiTi alloy, is a single-use, rotary file that enables shaping of the full length of the canal with a single instrument, directly to the apex with patented variable cross-section all along the blade for apical third centering ability and excellent debris removal up to the medium and coronal parts.
Observing changes in root canal anatomy before and after instrumentation is difficult in a two-dimensional radiograph. Therefore, in sectional imaging for endodontic diagnosis, Cone beam computed tomography. It can aid in the diagnosis of periapical lesions, the demonstration of the complex anatomy of the root canal system, internal and external resorptions, the detection of vertical root fractures, and the identification of lateral and accessory canals.
The study aims to assess the canal transportation and centering ability of rotary and reciprocating file systems using cone-beam computed tomography (CBCT) imaging.
The null hypothesis was that there is no difference in the canal transportation and centering ability with reciprocating and rotary file systems.
| Materials and Methods|| |
The present study consisted of sixty freshly extracted mandibular first molars with mesiobuccal canals, fully formed apices having angles of curvature within 10°–12° (according to Schneider method) with curvature radius <10° and minimum length 19 mm that had been extracted for periodontal or orthodontic reasons. All the teeth were cleaned, disinfected, and stored in saline at 4°C until use.
Preparation of the specimens
Roots were embedded into modeling wax, which was simulated in mandibular arch form. Working length was established by advancing #10 k file into the canal until just visible at the apical foramen and then subtracting 1 mm from it.
The three balanced groups were randomly assigned to be instrumented with Group 1 (WaveOne Gold), Group 2 (TruNatomy), and Group 3 (One Curve) with twenty teeth each (n = 20). A preinstrumentation CBCT scan was taken at this point [Figure 1]a, [Figure 1]b, [Figure 1]c. All groups were first enlarged to a size 20 K-file following which, they were subjected to instrumentation with Group 1 (WaveOne Gold) size #25 and taper of 0.07 was used in the “WaveOne ALL'' mode by the endomotor at 350 rpm, Group 2 (TruNatomy) prime file (26. 0/04) was used at 500 rpm with a torque of 1.5 Ncm, and Group 3 (One Curve) with size #25 and taper of 0.06 was used at 300 rpm with a torque of 2.5 Ncm according to the manufacturer's instructions.
|Figure 1: CBCT images (a-c) before and (d-l) after instrumentation at 2, 3, and 4 mm. Canal (d, g, and j) was instrumented by a WaveOne Gold file, canal (e, h, and k) was instrumented by TruNatomy file and canal (f, i and l) was instrumented by One Curve file. CBCT: Cone beam computed tomography|
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In all groups, irrigation was done with 2 ml of 2.5% NaOCL, and the procedure was repeated until the file reaches the working length.
CBCT images were repeated after preparation for all teeth with the same exposure parameters as preoperative scan [Figure 1]d, [Figure 1]e, [Figure 1]f, [Figure 1]g, [Figure 1]h, [Figure 1]i, [Figure 1]j, [Figure 1]k, [Figure 1]l. Mesiodistal and buccolingual dimensions are recorded at 2, 3, and 4 mm from the apex in both preoperative and postoperative scans.
All the CBCT scans under evaluation were analyzed using Carestream three-dimensional (3D) imaging software to calculate quantitative parameters and construct visual 3D models. The volume of interest for each specimen, extending from the furcation region to the apex of the mesial root, was set by integrating regions of interest in all of the cross-sections. The grayscale range was required to recognize the dentin before and after instrumentation was determined using a density histogram with the global threshold method.
Root canal transportation analysis
For root canal transportation analysis, axial sections corresponding to distances of 2, 3, and 4 mm from the anatomic apex were selected.
Canal transportation was calculated in millimeters using the formulas [Figure 1]:
(a1 − a2) − (b1 − b2)
In this formula, a1 is the least distance between mesial borders of the root and the canal before instrumentation, a2 is the least distance between mesial borders of the root and the canal after instrumentation, b1 is the least distance between distal borders of the root and the canal before instrumentation, and b2 is the least distance between distal borders of the root and the canal after instrumentation.
(c1 − c2) − (d1 − d2)
In this formula, c1 is the least distance between the buccal borders of the root and the canal before instrumentation, c2 is the least distance between the buccal borders of the root and the canal after instrumentation, d1 is the least distance between the lingual borders of the root and the canal before instrumentation, and d2 is the least distance between the lingual borders of the root and the canal after instrumentation.
According to these formulas, 0 means no canal transportation, whereas positive and negative values show mesial and buccal and distal or lingual transportation, respectively.
Centering ability was determined by a1 − a2/b1 − b2 or b1 − b2/a1 − a2 formulas.
According to this formula, a result of 1 indicated the optimal-centering ability and closer the result to zero the worse the ability of the instrument to keep itself in canal central axis. The data obtained were subjected to statistical analysis.
| Results|| |
Statistical analysis was done using Product and Service Solutions (SPSS) version 21 for Windows (Armonk, NY, USA: IBM Corp.). Descriptive quantitative data were expressed in mean and standard deviation, respectively. Data normality was checked using Shapiro–Wilk test. The confidence interval is set at 95% and the probability of alpha error (level of significance) is set at 5%. The power of the study was set at 80%. Comparisons of canal transportation and centering ability will be performed by analysis of variance test. Multiple pair-wise intergroup comparison among the three groups will be done with the help of Tukey's post hoc test. A comparison of canal transportation and centering ability between reciprocating and rotary file systems will be performed using unpaired “t”-test.
In the present study, at all the three levels (2, 3, and 4 mm from the apex), the WaveOne gold had the lowest canal transportation in both mesiodistal and buccolingual diameters, whereas One Curve had the highest [Table 1], [Table 2], [Table 3]. The difference in transportation amounts in the three groups was not statistically significant (P > 0.05). WaveOne gold showed the highest centering ability (nearest to complete centering), whereas One Curve showed the lowest at all the 3 levels [Table 1], [Table 2], [Table 3]. The difference in the centering ability in the three groups was statistically significant (P < 0.001).
|Table 1: Comparative evaluation of mesiodistal canal transportation, buccolingual canal transportation, and centering ability between Group 1 (WaveOne Gold), Group 2 (TruNatomy), and Group 3 (One Curve) files, respectively, at 2 mm levels|
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|Table 2: Comparative evaluation of mesiodistal canal transportation, buccolingual canal transportation, and centering ability between Group 1 (WaveOne Gold), Group 2 (TruNatomy), and Group 3 (One Curve) files, respectively, at 3 mm levels|
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|Table 3: Comparative evaluation of mesiodistal canal transportation, buccolingual canal transportation, and centering ability between Group 1 (WaveOne Gold), Group 2 (TruNatomy), and Group 3 (One Curve) files, respectively, at 4 mm levels|
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| Discussion|| |
For successful endodontic treatment, it is imperative to maintain the natural anatomy of the root canals and not creating any iatrogenic errors. Most of the errors during canal preparation happen due to rigid nature, lack of flexibility, and shape memory of the endodontic instruments which leads to unequal distribution of forces at the point of contact with the root canal wall during cleaning and shaping procedure, leading to transportation. Blockage, root perforation, and ledge are some of the complications which can occur due to transportation and which may finally compromise the root–dentin and apical seal. Furthermore, these complications will leave an uninstrumented area in the canal which may further affect the integrity of the periapical tissues.
Centering ability of the instrument allows uniform preparation and equal removal of dentin from the canal walls. In this study, besides transportation ability of the instruments, centering ability was also assessed.
In the present study, the null hypothesis was rejected as Group 1 WaveOne gold had the lowest transportation and highest centering ability at 2, 3, and 4 mm from the apex [Table 1], [Table 2], [Table 3]. These findings could be attributed to the fact that instrument in reciprocation is claimed to continuously progresses toward the apex of the root canal which explains the lesser apical transportation seen in reciprocating group. Flexibility could be another adjunct for lesser transportation in these groups along with reciprocating motion as M-Wire of WaveOne was found to be more flexible than traditional alloy.
Similarly, in a study by Thota et al., root canal transportation was maximum at all the levels with ProTaper compared with WaveOne. The unique design of WaveOne file with two different cross-sections along the length of active portion is one of the prime reasons for decreased core diameter, leading to increased flexibility of the file. Active portion of the file also has changing pitch and helical angle which further helped in decreasing the core diameter. Increased canal centering ability is one of the characteristic features of reciprocating motion, which was proposed primarily to reduce the risk of root canal deformity. Similar results were found in a study by Tambe et al., in which WaveOne files caused lesser transportation and remained better centered in the canal than One Shape and Rotary ProTaper files. Results were consistent with the findings of Saber et al. which compared the shaping ability of WaveOne, Reciproc, and OneShape file systems. Similarly, other studies such as Franco et al., Hwang et al., Maia Filho et al., and others found that instruments when used in reciprocation motion caused the least canal transportation and exhibited the highest centering ability than used in continuous motion.
On the contrary, Poly et al. and others revealed a significantly better-centering ability and less canal transportation with XP-endo shaper (rotary system) compared to WaveOne Gold (reciprocating system). Similar results were found in a study by Kabil et al. This could be attributed to its less flexibility compared with other files of the same tip size because of their greater taper over the first 3 mm.
In the present study, TruNatomy showed the highest canal transportation and lowest centering ability than WaveOne gold [Table 1], [Table 2], [Table 3]. The outcome slightly differs from the study by Kim et al., where TruNatomy kept the original apical canal curvature better than WaveOne GOLD. This could be due to the fact that TruNatomy (TRN), the newly developed file system, is made with a slim NiTi wire with a 0.8 mm maximum flute diameter and an off-centered parallelogram cross-sectional design, as well as a special heat treatment that accounts for its higher flexibility and superior canal-centering ability while preserving tooth structure.
In the present study, Group 3 One Curve had the highest canal transportation and the lowest centering ability, compared to Group 1 WaveOne Gold and Group 2 TruNatomy file systems [Table 1], [Table 2], [Table 3]. The findings are consistent with the findings of Singla et al., who discovered that One Curve has the highest canal transportation. This could be attributed to One Curve's variable cross-section and continuous motion directly to the apical foramen causing more changes in root canal curvature than the other two systems. However, according to a study by Tufenkci et al., One Curve has the lowest canal transportation in comparison to ProTaper Next and One Shape rotary systems. This was due to its triangular cross-sectional geometry, whereas Protaper Next (PTN) file has a rectangular shape with an off-centered mass and its regressive taper can be more efficient in the contact area of the canal.
| Conclusion|| |
Within the limitations of the study, it can be concluded that reciprocating file system, WaveOne Gold, demonstrated less canal transportation and better-centering ability than the rotary system that is TruNatomy and One Curve at all the three levels in the current study.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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Dr. Tanisha Singh
Sector PI, ITBP Housing Society Flat No. 313, Greater Noida, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
[Table 1], [Table 2], [Table 3]