ORIGINAL RESEARCH |
https://doi.org/10.5005/jp-journals-10015-2267 |
Comparative Evaluation of Root Canal Centering Ability of Two Heat-treated Single-shaping NiTi Rotary Instruments in Simulated Curved Canals: An In Vitro Study
1Department of Conservative Dentistry and Endodontics, KSR Institute of Dental Science and Research, Tiruchengode, Tamil Nadu, India
2-4Department of Conservative Dentistry and Endodontics, Sri Ramachandra Dental College and Hospital, Sri Ramachandra Institute of Higher Education and Research (Deemed to be University), Chennai, Tamil Nadu, India
Corresponding Author: Mathan R R, Department of Conservative Dentistry and Endodontics, Sri Ramachandra Dental College and Hospital, Sri Ramachandra Institute of Higher Education and Research (Deemed to be University), Chennai, Tamil Nadu, India, Phone: +91 9841414604, e-mail: mathanrajanr@sriramachandra.edu.in
Received on: 01 May 2023; Accepted on: 03 June 2023; Published on: 22 August 2023
ABSTRACT
Aim: To evaluate the canal centering ability of two heat-treated single-shaping nickel-titanium (NiTi) rotary files in simulated severely curved canals.
Materials and methods: Standardized 40 resin blocks with 35° simulated curved canals were randomly divided into two groups according to the instrumentation systems, group I: TruNatomy (n = 20) and group II: XP-endo Shaper (n = 20). Before instrumentation, the resin blocks with an endodontic ruler fixed were photographed in a standardized setup at a magnification ratio (1:4). The simulated canals were instrumented according to the manufacturer’s instructions for each system and irrigated in-between with normal saline. After instrumentation, resin blocks were photographed in the same preinstrumentation setup. The pre- and postinstrumentation images stored in JPEG format were sketched with Adobe Photoshop software CS5 using the filter “sketch” (green and red color, respectively). They were superimposed using the same software, and on the canal profile, 5 points of measurement were traced at 1, 2, 3, 5, and 7 mm from the apex representing the apical, middle, and coronal third, respectively. The mean canal centering ratio (CR) was compared for both groups at all the levels of measurement using a nonparametric Mann–Whitney U test. Intergroup and intragroup multiple comparisons of the mean canal CR at each of the measuring points against all the measuring points were conducted using the post hoc Tukey test.
Results: The results showed that no significant statistical difference was evident within the same group and between the two groups at all the points of measurement (p > 0.05).
Conclusion: TruNatomy and XP-endo Shaper showed comparable canal centering ability in severely curved canals.
Clinical significance: These heat-treated single shaping files would thus empower the clinicians to adhere to the ultraconservative access designs, while achieving an adequate and predictable apical preparation within a shorter duration of time.
How to cite this article: Shaji A, R MR, Varadan P, et al. Comparative Evaluation of Root Canal Centering Ability of Two Heat-treated Single-shaping NiTi Rotary Instruments in Simulated Curved Canals: An In Vitro Study. World J Dent 2023;14(6):535-540.
Source of support: Nil
Conflict of interest: None
Keywords: Centering ability, Heat treated files, Severely curved canals, Single shaping files.
INTRODUCTION
Successful root canal treatment is dependent on effective shaping and cleaning of the root canal system. Canal shaping optimizes the shape of the canal for adequate disinfection and a three-dimensional obturation that has a profound effect on the survival and long-term integrity of the tooth.1
The means of acquiring an ideal chemo-mechanical preparation is primarily achieved through the canal-centering ability of an instrument.2 Canal centering is defined as the ability of the instrument to remain centered in the root canal system.3 The centered nickel-titanium (NiTi) instrument provides an adequate enlargement of the root canal without excessive weakening of the root structure.4
With the evolution of time, the canal centering ability of NiTi instruments was optimized, which improved the safety and clinical performance during endodontic procedures. The advancements in NiTi manufacturing technology thus influenced the manufacturer to bring about changes with respect to instrument design (cross-section, flute diameter, taper, tip diameter, and its motion inside the canal), alteration to the surface of the alloy (ion implantation and electropolishing), and alteration of the alloy microstructure (heat treatment or innovative manufacturing techniques). These resulted in achieving a centered canal preparation due to the improved instrument flexibility, fatigue resistance, cutting efficiency, and better debris removal from the inner portion of the root canal.5 By introducing these newly developed NiTi instruments into clinical practice along with maintenance of the glide path and patency of the canal (before and during instrumentation), operators can achieve superior canal centering of the instruments. This has significantly reduced the occurrence of procedural errors such as elbow, zips, perforations, and transportation.6
The revolutions in the NiTi system have brought about the single shaping S-files with better canal centering ability, which made the endodontic procedure more operator friendly. One such innovation is TruNatomy (TN; Dentsply Sirona, Maillefer, Ballaigues, Switzerland), a special heat-treated NiTi rotary instrument manufactured from 0.8 mm NiTi wire instead of 1.2 mm NiTi wire that is used for most of the generic files, posing an advantage of improved flexibility in severely curved canals, maintaining the root canal anatomy along with preservation of pericervical dentin. The TruNatomy shaping file has an off-centered parallelogram cross-section.7
The other new NiTi system included in this current study is the XP-endo Shaper (XP; FKG Dentaire, La Chaux-de-Fonds, Switzerland), which is a single shaping NiTi file with a unique metallurgy manufactured from Max Wire technology (Martensite–Austenite Electropolishing Flex) allowing the instrument to expand and contract within the root canal. The instrument is designed with six cutting edges for optimal guidance and has the ability to shape the canal from size 15 to 30. This unique Max Wire technology provides superior resistance to cyclic fatigue with extreme flexibility that enables the XP-endo Shaper files to access areas that conventional instruments cannot access without causing extensive stress to the dentin.8
However, there is limited literature available on comparing these two different single-shaping file systems with regard to their centering ability within the root canal system. Hence the aim of this study was to evaluate the canal centering ability of the two newly introduced heat-treated single-shaping NiTi rotary instruments differing in metallurgy and instrument design in simulated severely curved canals using standardized resin blocks.
MATERIALS AND METHODS
Sample Preparation
The study was carried out in accordance with the Declaration of Helsinki and approved by the Institutional Ethical Committee with an approval ID (CSP 19 January 75/54, dated 18th February 2019). Standardized 40 simulated curved canals in clear resin blocks (V040245, Dentsply) with 35° canal curvature were utilized in the study. The resin blocks were numbered from 1 to 40 and were divided into two groups, group I: TruNatomy (n = 20) and group II: XP-endo Shaper (n = 20).
Preinstrumentation Photographs
The resin blocks were photographed in a standardized setup prior to instrumentation. The standardized setup allowed placement of the digital camera (Canon EOS 5D with SIGMA 105 mm lens and magnification ratio of 1:4) in a fixed position using a tripod stand and a platform for repositioning the resin block.9 For calibration and ensuring exact superimposition, an endo ruler (Dentsply–Maillefer, Ballaigues) was fixed, and each resin block was placed adjacent to the fixed endo ruler.10
Shaping of the Root Canal
All the shaping and cleaning procedures were performed by a single operator according to the manufacturer’s instructions. The working length was determined as 16 mm from the start of the canal to the canal terminus. In group I, the resin blocks were shaped using the TruNatomy file system at 500 rpm and 1.5 Ncm. The canal patency was achieved by a 10 K hand file (#10/0.02) followed by orifice enlargement using TruNatomy orifice modifier (#20/0.08). Subsequently, the TruNatomy Glider (#17/0.02) was used to achieve the glide path, and apical enlargement was achieved using TruNatomy Prime shaping file (#26/0.04). In group II, the resin blocks were shaped using the XP-endo Shaper file system at 800 rpm and 1 Ncm. The initial canal patency was achieved with a size 10 K hand file (#10/0.02), and eventually, the glide path was obtained by a size 15 K hand file (#15/0.02), and the final shaping of the canal was done up to the apical preparation size of #30/04 using XP-endo Shaper shaping file. Between the instrumentation, the resin blocks were irrigated with 2 mL of normal saline, and simulated canal patency was checked with a size 10 K hand file.11 The flutes of the instruments were cleaned with moist gauze. All the instruments were replaced after the preparation of four resin blocks.12 After shaping, the resin blocks were photographed in the same standardized setup used for the preinstrumentation photographs.
Assessment of the Canal Centering Ability
Pre and postinstrumentation images were stored in the JPEG format. Images were processed with a computer software program (Adobe Photoshop software CS5) using the filter (“sketch”) and were then superimposed. Preoperative images were sketched in green color, and postinstrumentation images were sketched in red color for enhancing the contrast of the margins during measurement. The ability of the instruments to remain centered was determined by calculating the centering ratio (CR) at five measuring points which were traced at 1, 2, 3, 5, and 7 mm from the apex representing an apical, middle, and coronal third of the canal (Fig. 1).13
Fig. 1: Depiction of parameters of canal CR
The canal CR was calculated for both groups using Adobe Photoshop CS5 software. The canal CR was obtained from the superimposed preinstrumentation image (sketched in green) and postinstrumentation image (sketched in red) with the help of the formula (X1 − X2)/Y were:
-
X1: Maximum extent of canal movement in one direction.
-
X2: Minimum extent of canal movement in the opposite direction.
-
Y: Diameter of final canal preparation.
Canal CR at each of the measuring points 1, 2, 3, 5, and 7 mm for the TruNatomy group (group I) were represented as CRT1, CRT2, CRT3, CRT5, and CRT7, respectively, and CRX1, CRX2, CRX3, CRX5, and CRX7, respectively for XP-endo Shaper group (group II). The mean CR approximating to value zero will be considered to provide more centered canal preparation.
The statistical analysis was performed using Statistical Package for the Social Sciences software version 20 software (IBM Corp., Armonk, New York, United States of America). Descriptive statistics were obtained for the data. The normality test was carried out using the Shapiro–Wilk test followed by the nonparametric Mann–Whitney U test to compare the mean CR between the two groups at each of the measuring points. Post hoc Tukey multiple comparison test was used for the comparison of the canal CR at each of the measuring points against all the other measuring points between and within the same groups. The statistically significant difference was set at 0.05.
RESULTS
The mean CR for the TruNatomy group (group 1) at 1, 2, 3, 5, and 7 mm were 0.147, 0.195, 0.156, 0.147, and 0.138, respectively. In the XP-endo Shaper group (group II), the mean CR obtained were 0.188, 0.144, 0.190, 0.138, and 0.142 at 1, 2, 3, 5, and 7 mm, respectively. The standard deviation for both groups at all levels is mentioned in Table 1. The mean values showed that TruNatomy had better canal centering ability at 2 mm from the apex, and XP-endo Shaper performed better at 3 mm from the apex when compared to the other measuring points in their respective group. However, there was no statistically significant difference in the mean CR on the intergroup comparison at 1, 2, 3, 5, and 7 mm with p-value 0.096, 0.086, 0.829, 0.238, and 0.337, respectively, as illustrated in Table 2.
Group | N | Mean | Standard deviation | Group |
---|---|---|---|---|
1 mm | CRT1 | 20 | 0.147 | 0.125 |
CRX1 | 20 | 0.188 | 0.103 | |
2 mm | CRT2 | 20 | 0.195 | 0.108 |
CRX2 | 20 | 0.144 | 0.060 | |
3 mm | CRT3 | 20 | 0.156 | 0.064 |
CRX3 | 20 | 0.190 | 0.128 | |
5 mm | CRT5 | 20 | 0.147 | 0.072 |
CRX5 | 20 | 0.138 | 0.087 | |
7 mm | CRT7 | 20 | 0.138 | 0.058 |
CRX7 | 20 | 0.142 | 0.098 |
The CR at 1, 2, 3, 5, and 7 mm represented as CRT1, CRT2, CRT3, CRT5, and CRT7 for TruNatomy group (group I) and CRX1, CRX2, CRX3, CRX5, and CRX7 for XP-endo Shaper group (group II)
At 1 mm | At 2 mm | At 3 mm | At 5 mm | At 7 mm | |
---|---|---|---|---|---|
Mann–Whitney U | 138.5 | 136.5 | 192.0 | 156.5 | 164.5 |
Wilcoxon W | 348.5 | 346.5 | 402.0 | 366.5 | 374.5 |
Z | −1.664 | −1.719 | −0.217 | −1.181 | −0.961 |
Asymp. significance (2-tailed) | 0.096 | 0.086 | 0.829 | 0.238 | 0.337 |
Exact significance [2*(1-tailed significant)] | 0.096 | 0.086 | 0.841 | 0.242 | 0.341 |
On performing the post hoc Tukey multiple comparison test, both the intergroup and intragroup comparisons revealed no statistically significant difference in the obtained values with a 95% confidence interval at each of the measuring points against all the other measuring points (p ≤ 0.05) (Tables 3 and 4).
Sample (I) | Sample (J) | Mean difference (I−J) | Significance |
---|---|---|---|
CRT1 | CRX1 | −0.040 | 0.82 |
CRX2 | 0.004 | 1.00 | |
CRX3 | −0.042 | 0.78 | |
CRX5 | 0.009 | 1.00 | |
CRX7 | 0.005 | 1.00 | |
CRT2 | CRX1 | 0.007 | 1.00 |
CRX2 | 0.051 | 0.593 | |
CRX3 | 0.005 | 1.00 | |
CRX5 | 0.057 | 0.471 | |
CRX7 | 0.052 | 0.564 | |
CRT3 | CRX1 | −0.032 | 0.884 |
CRX2 | 0.012 | 0.999 | |
CRX3 | −0.034 | 0.853 | |
CRX5 | 0.018 | 0.991 | |
CRX7 | 0.013 | 0.998 | |
CRT5 | CRX1 | −0.040 | 0.755 |
CRX2 | 0.004 | 1.00 | |
CRX3 | −0.042 | 0.712 | |
CRX5 | 0.009 | 1.00 | |
CRX7 | 0.005 | 1.00 | |
CRT7 | CRX1 | −0.050 | 0.514 |
CRX2 | −0.007 | 1.00 | |
CRX3 | −0.053 | 0.467 | |
CRX5 | −0.0008 | 1.00 | |
CRX7 | −0.005 | 1.00 | |
CRX1 | CRT1 | 0.040 | 0.738 |
CRT2 | −0.007 | 1.00 | |
CRT3 | 0.032 | 0.879 | |
CRT5 | 0.040 | 0.737 | |
CRT7 | 0.051 | 0.508 | |
CRX2 | CRT1 | −0.004 | 1.00 |
CRT2 | −0.051 | 0.418 | |
CRT3 | −0.012 | 0.998 | |
CRT5 | −0.003 | 1.00 | |
CRT7 | 0.007 | 1.00 | |
CRX3 | CRT1 | 0.042 | 0.739 |
CRT2 | −0.005 | 1.000 | |
CRT3 | 0.034 | 0.874 | |
CRT5 | 0.042 | 0.739 | |
CRT7 | 0.053 | 0.522 | |
CRX5 | CRT1 | −0.009 | 0.999 |
CRT2 | −0.057 | 0.342 | |
CRT3 | −0.018 | 0.989 | |
CRT5 | −0.009 | 0.999 | |
CRT7 | 0.0008 | 1.000 | |
CRX7 | CRT1 | −0.005 | 1.000 |
CRT2 | −0.052 | 0.462 | |
CRT3 | −0.013 | 0.997 | |
CRT5 | −0.005 | 1.000 | |
CRT7 | 0.005 | 1.000 |
Centering ratio (CR) at 1, 2, 3, 5, and 7 mm represented as CRT1, CRT2, CRT3, CRT5, and CRT7 for TruNatomy group (group I) and CRX1, CRX2, CRX3, CRX5, and CRX7 for XP-endo Shaper group (group II)
Ti | Sample (J) | Mean difference (I−J) | Significance |
---|---|---|---|
CRT1 | CRT2 | −0.047 | 0.461 |
CRT3 | −0.008 | 0.999 | |
CRT5 | 0.000 | 1.000 | |
CRT7 | 0.010 | 0.996 | |
CRT2 | CR T1 | 0.047 | 0.461 |
CRT3 | 0.039 | 0.643 | |
CRT5 | 0.047 | 0.460 | |
CRT7 | 0.057 | 0.259 | |
CRT3 | CRT1 | 0.008 | 0.999 |
CRT2 | −0.039 | 0.643 | |
CRT5 | 0.008 | 0.998 | |
CRT7 | 0.018 | 0.965 | |
CRT5 | CRT1 | −0.000 | 1.000 |
CRT2 | −0.047 | 0.460 | |
CRT3 | −0.008 | 0.998 | |
CRT7 | 0.010 | 0.996 | |
CRT7 | CR T1 | −0.010 | 0.996 |
CRT2 | −0.057 | 0.259 | |
CRT3 | −0.018 | 0.965 | |
CRT5 | −0.010 | 0.996 | |
CRX1 | CRX2 | 0.043 | 0.617 |
CRX3 | −0.002 | 1.000 | |
CRX5 | 0.049 | 0.496 | |
CRX7 | 0.045 | 0.589 | |
CRX2 | CRX1 | −0.043 | 0.617 |
CRX3 | −0.046 | 0.573 | |
CRX5 | 0.006 | 1.000 | |
CRX7 | 0.001 | 1.000 | |
CRX3 | CRX1 | 0.002 | 1.000 |
CRX2 | 0.046 | 0.573 | |
CRX5 | 0.052 | 0.452 | |
CRX7 | 0.047 | 0.544 | |
CRX5 | CRX1 | −0.050 | 0.496 |
CRX2 | −0.005 | 1.000 | |
CRX3 | −0.052 | 0.452 | |
CRX7 | −0.004 | 1.000 | |
CRX7 | CRX1 | −0.045 | 0.589 |
CRX2 | −0.001 | 1.000 | |
CRX3 | −0.047 | 0.544 | |
CRX5 | 0.004 | 1.000 |
Centering ratios (CRs) at 1, 2, 3, 5, and 7 mm represented as CRT1, CRT2, CRT3, CRT5, and CRT7 for TruNatomy group (group I) and CRX1, CRX2, CRX3, CRX5, and CRX7 for XP-endo Shaper group (group II)
Hence from the results, it can be inferred that in simulated severely curved canals, the TruNatomy file system was as effective as the XP-endo Shaper file system in maintaining the original root canal anatomy.
DISCUSSION
Shaping and cleaning of root canals are considered the primary prognostic factor in root canal treatment success. Ideal instrumentation should achieve both the mechanical objectives (centered preparation and preservation of pericervical dentin), and biological objective of disinfecting the root canal system.14 Conventional nonheat-treated NiTi systems with centric rotation tends to straighten themselves within a curved root canal due to their shape memory; resulting in exerting lateral force upon the root canal wall, leading to canal transportation.15 However, there have been major improvements in the treatment of NiTi instruments to enhance their flexibility with controlled shape memory, such as electropolishing, electrodischarge machining, and thermal treatment protocols. These improvements minimize the canal transportation potential while achieving faster and more predictable canal preparation.16
Despite the aforementioned advances in NiTi metallurgy and different instrumentation techniques, procedural errors, though minimized, still occur, as all instruments tend to alter the pathway of the root canal. The anatomic complexities of the root canal, such as canal curvatures of 30° or more, still pose a challenge in establishing an optimized centered canal preparation. On taking into account such canal complexities, a simulated canal with 35° curvature was used to study the canal centering ability.
In general, simulated resin blocks or extracted natural teeth are used for assessing canal preparations. However, natural teeth pose a disadvantage of numerous variations with respect to canal anatomy and morphology. In the present study, resin blocks with simulated curved canals of 35° were chosen, as it offers an advantage in terms of standardization of canal length, degree of canal curvature, and diameter of the root canal. The three-dimensional standardization of canal morphology provides an identical experimental model for the evaluation of the instruments used despite the differences in the mechanical properties of the resin and human dentine.17
The photographic method was used in the current study for assessing the canal centering ability that relies on using fixed devices for capturing images and software for superimposition of the resin block images. It is considered to be an accurate method as it has a high degree of reproducibility, ease of calculation, is inexpensive, and allows simultaneous comparison of the root canal morphology before and after instrumentation.18 Among the various methods used in the evaluation of the canal centering ability, the CR method utilized in this study was the most accurate as it provides precise qualitative and quantitative measurements.19
Currently, pericervical dentin preservation is considered to be the most significant factor in determining the long-term prognosis of the tooth in function by maintaining its structural integrity. The pericervical dentin is often compromised during access cavity preparation with access burs and also during canal orifice enlargement using Gates Glidden drills or orifice shapers. In order to preserve this, various modifications in access cavity preparations were proposed, which include conservative access cavity designs, ultraconservative designs, and ninja access designs. These contracted access cavities pose increased difficulty for cleaning and shaping as they limit conventional straight-line access. The difficulties posed by the shaping and cleaning procedures in contracted access cavities were addressed by the NiTi manufacturers using different thermo-mechanical treatments and metallurgy focusing on improving canal centering ability due to the enhanced flexibility of the instrument.20
The performance of the file to remain centered in the canal is greatly influenced by the metallurgy and design of the instrument. The enhanced flexibility thus helped in addressing the three sacred tenets for shaping the canals; Safety, effectiveness, and simplicity while maintaining the original anatomy of the canal.21 In the current study, two newly introduced asymmetrical single-shaping NiTi rotary instruments, TruNatomy and XP-endo Shaper, were evaluated for their canal-centering ability.
Conventional NiTi files have transformational elasticity, also known as pseudoelasticity, or the ability to return to their original shape, and are temperature and strain-dependent. The stable phases of NiTi alloys possess specific crystal arrangements, namely the austenite and martensite phases. Literature evidence suggests that the conventional centric NiTi files with active cutting flutes show a greater tendency to straighten the curved canals leading to increased canal aberrations.22-24 Therefore, various attempts have been made to improve the drawbacks in the mechanical properties of such traditional NiTi files.
The results of the current study, which utilized two such NiTi rotary files, TruNatomy, and XP-endo Shaper, revealed no significant statistical difference at all the measuring levels between the groups and within the same group. Our results were concurrent to the study results obtained by Shaheen and Elhelbawy,25 which concluded that TruNatomy and XP-endo shaper showed similar shaping ability in extracted mandibular molars. These results confirmed that both the heat-treated NiTi file systems possess comparable canal-centering ability at all levels. This could be attributed to the stable martensite phase available under clinical conditions providing excellent flexibility. Moreover, the asymmetric rotation motion and small metal core of the instrument would have also contributed to the comparable canal CR.
The study by Morales et al.26 concluded that TruNatomy and XP-endo Shaper files maintained the canal’s original anatomy; however, TruNatomy contacted the canal surface at the lowest percentage (50%). The acceptable performance of the TruNatomy files in maintaining the original canal anatomy can be associated with the following features, such as the smallest metal core and diameter of the flute design (0.8 mm), the regressive variable taper, and the off-centered parallelogram cross-section.
On the evaluation of canal centering ability, the current study revealed that XP-endo Shaper NiTi files showed similar canal centering ability in comparison to TruNatomy at all the levels of measurement. Our results obtained were in agreement with Ozturk B et al.27 and Majumdar et al.28 in terms of centered preparation obtained with XP-endo Shaper files. Ozturk B et al. which compared the centering ability of ProTaper Next and XP-endo Shaper, revealed that XP-endo Shaper caused lesser transportation than ProTaper Next at all three apical sizes 30, 35, and 40 on all thirds, such as coronal, middle, and apical third on cone-beam computed tomography analysis. Majumdar et al.,28 in their study, also showed that XP-endo Shaper showed centered preparation at 2, 4, and 6 mm from the apex in comparison to the ProTaper Gold system. This ability to maintain the original canal anatomy could be ascribed to the following features of the XP-endo Shaper such as snake-shaped single shaping file, adaptive core instrument, the equilateral triangular cross-section, the Max-Wire technology of the NiTi alloy, and the booster tip geometry. However, in contrast to our results, XP-endo Shaper showed less centered preparation than Edge Evolve NiTi files at five different levels of measurement, which could be due to superelastic, snake-shaped XP-endo Shaper files possessing extreme flexibility. When combined with continuous rotation at an extreme speed of 800–1000 RPM and minimal torque, the XP-endo Shaper files may not remain centered in the canal during instrumentation.29
The other NiTi system TruNatomy in this study also showed acceptable centered preparation on all the thirds of the canal, which was similar to the results obtained in Berutti et al.,30 which compared TruNatomy with ProTaper Next files. The unique slim design of the TruNatomy file system, 0.8 mm NiTi wire instead of 1.2 mm, avoids the removal of excess dentin from the radicular walls preventing structural defects such as canal transportation during biomechanical preparation and providing centered preparation. In contrast to our study results, Kim et al.31 revealed that TruNatomy showed deviation between the mesial and distal sides of the canal in the coronal area at 6, 7, 8, and 9 mm levels of the canal. However, the study concluded that TruNatomy maintained the original canal anatomy in comparison to the other two systems studied, WaveOne Gold and ProTaper Gold.
Within the limitations of the current study, it can be inferred that both the TruNatomy and XP-endo Shaper file systems showed comparable canal centering ability in severely curved canals.
Limited evidence exists on the newly introduced single file system; hence further aspects of rotary files can be studied. More randomized clinical trials need to be carried out for more clinical relevance. Thus, it can be inferred from the results that both the TruNatomy and XP-endo Shaper file systems showed comparable canal-centering ability in severely curved canals. Hence these file systems can be advocated by the clinician in teeth with complex root canal systems making the procedure more operator friendly with minimum iatrogenic errors.
CONCLUSION
Within the limitations of the study, it can be concluded that. TruNatomy and XP-endo Shaper showed comparable centering ability at all the points of measurement in severely curved canals. The proprietary thermal treatment, smaller instrument core, along with offset cross-section exhibited by both instruments contributed to maintaining the original anatomy of the simulated canals. These heat-treated single shaping files would thus empower the clinicians to adhere to the ultraconservative access designs while achieving an adequate and predictable apical preparation within a shorter duration of time.
REFERENCES
1. Kandaswamy D, Venkateshbabu N, Porkodi I, et al. Canal-centering ability: An endodontic challenge. J Conserv Dent 2009;12(1):3–9. DOI: 10.4103/0972-0707.53334
2. Nagendrababu V, Ahmed HMA. Shaping properties and outcomes of nickel-titanium rotary and reciprocation systems using micro-computed tomography: a systematic review. Quintessence Int 2019;50(3):186–195. DOI: 10.3290/j.qi.a41977
3. Gundappa M, Bansal R, Khoriya S, et al. Root canal centering ability of rotary cutting nickel titanium instruments: a meta-analysis. J Conserv Dent 2014;17(6):504–9. DOI: 10.4103/0972-0707.144567
4. Stavileci M, Hoxha V, Görduysus Ö, et al. Effects of preparation techniques on root canal shaping assessed by micro-computed tomography. Med Sci Monit Basic Res 2013;19:163–8. DOI: 10.12659/MSMBR.889350
5. Haapasalo M, Shen Y. Evolution of nickel-titanium instruments: from past to future. Endodont Topics 2013;29(1):3–17. DOI: 10.1111/etp.12049
6. Srivastava S, Alghadouni MA, Alotheem HS. Current strategies in metallurgical advances of rotary NiTi instruments: a review. J Dent Health Oral Disord Ther 2018;9(3):00333. DOI: 10.15406/jdhodt.2018.09.00333
7. The TruNatomy Brochure, Ballaigues, Switzerland, Dentsply Sirona. Available from: https://www.dentsplysirona.com/en/explore/endodontics/TruNatomy.html
8. The XP-endo Shaper brochure, FKG Dentaire. Available at: https://www.fkg.ch/sites/default/files/201612_fkg_XPS_brochure_v3_en_web.pdf
9. Muñoz E, Forner L, Garcet S, et al. Canal shaping with a reciprocating system is easy to learn. Int Endod J 2019;52(8):1244–1249. DOI: 10.1111/iej.13111
10. Goldberg M, Dahan S, Machtou P. Centering ability and influence of experience when using waveone single-file technique in simulated canals. Int J Dent 2012;2012:206321. DOI: 10.1155/2012/206321
11. Forghani M, Hezarjaribi M, Teimouri H. Comparison of the shaping characteristics of Neolix and Protaper universal systems in preparation of severely-curved simulated canals. J Clin Exp Dent 2017;9(4):e556–e559. DOI: 10.4317/jced.53476
12. Alfadley A, Alrajhi A, Alissa H, et al. Shaping ability of XP-endo Shaper file in curved root canal models. Int J Dent 2020;2020:4687045. DOI: 10.1155/2020/4687045
13. Elnaghy AM, Elsaka SE. Evaluation of root canal transportation, centering ratio, and remaining dentin thickness associated with ProTaper Next instruments with and without glide path. J Endod 2014;40(12):2053–6. DOI: 10.1016/j.joen.2014.09.001
14. Hargreaves KM, Berman LH. Cohen’s Pathways of Pulp First South Asian edition. Elsevier.
15. Zupanc J, Vahdat-Pajouh N, Schäfer E. New thermo-mechanically treated NiTi alloys - a review. Int Endod J 2018;51(10):1088–1103. DOI: 10.1111/iej.12924
16. Chasseb Al Khazali YH, Shukri B. A comparative study to evaluate canal transportation and centering ability of simulated curved canals prepared by XP-Shaper, WaveOne Gold and ProTaper NEXT files. Mustansiria Dent J 2018;15(1):18–24.
17. Hasheminia SM, Farhad A, Sheikhi M, et al. Cone-beam computed tomographic analysis of canal transportation and centering ability of single-file systems. J Endod 2018;44(12):1788–1791. DOI: 10.1016/j.joen.2018.09.011
18. Wei Z, Cui Z, Yan P, et al. A comparison of the shaping ability of three nickel-titanium rotary instruments: a micro-computed tomography study via a contrast radiopaque technique in vitro. BMC Oral Health 2017;17(1):39. DOI: 10.1186/s12903-016-0326-5
19. Di Nardo D, Miccoli G, Mazzoni A, et al. Centering ability of a new nickel-titanium rotary instruments with a peculiar flat-side design: an in vitro study. J Contemp Dent Pract 2020;21(5):539–542.
20. Vyver P, Vorster M, Peters O. Minimally invasive endodontics using a new single-file rotary system. Int Dent 2020;9(4):6–20.
21. Ruddle CJ, Machtou P, West JD. The shaping movement: fifth-generation technology. Dent Today 2013;32(4):96–9.
22. Troiano G, Dioguardi M, Cocco A, et al. Centering ability of ProTaper Next and WaveOne Classic in J-shape simulated root canals. Scientific World Journal 2016;2016:1606013. DOI: 10.1155/2016/1606013
23. Silva EJ, Muniz BL, Pires F, et al. Comparison of canal transportation in simulated curved canals prepared with ProTaper Universal and ProTaper Gold systems. Restor Dent Endod 2016;41(1):1–5. DOI: 10.5395/rde.2016.41.1.1
24. Park HJ, Seo MS, Moon YM. Root canal volume change and transportation by Vortex Blue, ProTaper Next, and ProTaper Universal in curved root canals. Restor Dent Endod 2017;43(1):e3. DOI: 10.5395/rde.2018.43.e3
25. Shaheen NA, Elhelbawy NGE. Shaping ability and buckling resistance of TruNatomy, WaveOne gold, and XP-endo Shaper single-file systems. Contemp Clin Dent 2022;13(3):261–266. DOI: 10.4103/ccd.ccd_1048_20
26. Pérez Morales MLN, González Sánchez JA, Olivieri JG, et al. Micro-computed tomographic assessment and comparative study of the shaping ability of 6 nickel-titanium files: an in vitro study. J Endod 2021;47(5):812–819. DOI: 10.1016/j.joen.2020.12.021
27. Arıcan Öztürk B, Atav Ateş A, Fişekçioğlu E. Cone-beam computed tomographic analysis of shaping ability of xp-endo shaper and protaper next in large root canals. J Endod 2020;46(3):437–443. DOI: 10.1016/j.joen.2019.11.014
28. Majumdar TK, Chowdhury M, Mukherjee S, et al. Cone-beam computed tomography assessment of root canal transportation and evaluation of canal centering using Protaper Gold, XP Endoshaper, and Edgefile X7. Endodontology 2022;34(2):121–126. DOI: 10.4103/endo.endo_146_21
29. Werdina VB, Bahnam IN. Evaluation of centering ability of XP-endo Shaper, Edge Evolve and Hyflex CM in simulated curved canals (a comparative study). EDJ 2019;2(1):130–4. DOI: 10.15218/edj.2019.02
30. Berutti E, Moccia E, Lavino S, et al. Micro-computed tomography evaluation of minimally invasive shaping systems in mandibular first molars. J Clin Med 2022;11(15): DOI: 10.3390/jcm11154607
31. Kim H, Jeon SJ, Seo MS. Comparison of the canal transportation of ProTaper GOLD, WaveOne GOLD, and TruNatomy in simulated double-curved canals. BMC Oral Health 2021;21(1):533. DOI: 10.1186/s12903-021-01854-z
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