Deformation and fracture incidence of Reciproc instruments: a clinical evaluation

Fracture Incidence of New Reciprocating Nickel-Titanium (NiTi) Files: A Cross-Sectional Retrospective Study

Aim This study aimed to evaluate the frequency of fractures in a new single-file reciprocating system used by endodontists. Methods Reciprocal systems were used to evaluate endodontist-treated patients' periapical radiographs and dental records. For the study, the kind of tooth, the quantity of root canals completed, the quantity of broken instruments, and the fragment's size were all recorded. A fracture risk calculation was made for every kind of tooth, root canal, and root third. The new reciprocating systems' fracture incidence was compared at a 5% significant level using the chi-squared test varied between 2 and 6 mm. Results There were a total of 5,066 root canals (2,128 teeth) from 1,818 patients. In single-file reciprocating systems, the incidence of fractured files relative to the number of instrumented canals was 22 (0.43%). The mesiobuccal root canal of mandibular molars and maxillary molars had the greatest breakage rates, which were 7 (36%) and 6 (27%), respectively. Conclusion The incidence of instrument fractures was lowered when linked to the usage of the Premium Blue reciprocating system in endodontic therapy.

3D Surface Scanning-A Novel Protocol to Characterize Virtual Nickel-Titanium Endodontic Instruments

The nickel-titanium (NiTi) instruments' geometry plays an important role in their performance and behavior. The present assessment intends to validate and test the applicability of a 3D surface scanning method using a high-resolution laboratory-based optical scanner to create reliable virtual models of NiTi instruments. Sixteen instruments were scanned using a 12-megapixel optical 3D scanner, and methodological validation was performed by comparing quantitative and qualitative measurements of specific dimensions and identifying some geometric features of the 3D models with images obtained through scanning electron microscopy. Additionally, the reproducibility of the method was assessed by calculating 2D and 3D parameters of three different instruments twice. The quality of the 3D models created by two different optical scanners and a micro-CT device was compared. The 3D surface scanning method using the high-resolution laboratory-based optical scanner allowed for the creation of reliable and precise virtual models of different NiTi instruments with discrepancies varying from 0.0002 to 0.0182 mm. The reproducibility of measurements performed with this method was high, and the acquired virtual models were adequate for use in in silico experiments, as well as for commercial or educational purposes. The quality of the 3D model obtained using the high-resolution optical scanner was superior to that acquired by micro-CT technology. The ability to superimpose virtual models of scanned instruments and apply them in Finite Element Analysis and educational purposes was also demonstrated.

Noncontact 3D evaluation of surface topography of reciprocating instruments after retreatment procedures

This study evaluated the Reciproc R25 and Pro-R 25 instruments in unused condition, after one and a second use in endodontic retreatment employing a noncontact 3D light interferometer profiler, scanning electron microscopy (SEM) and cyclic fatigue tests. Twenty single-root teeth were instrumented with Reciproc R25 and filled with gutta-percha and sealer. A 3D profiler with a 20x objective using the Mx™ software was used to evaluate the cutting blade surfaces of Reciproc R25 and Pro-R 25 (n=5 per group) in unused condition, after the first and second uses in retreatment procedures. After retreatment, SEM was used to evaluate the topographic features of the used instruments. Cyclic fatigue tests were performed to compare new to used instruments. One-way ANOVA followed by Tukey test was used to compare the tested instruments before and after the first and second uses. Student t-test was used to compare the different instruments and for cyclic fatigue evaluation. No significant differences were observed in the cutting blade surfaces of Reciproc and Pro-R before and after one and two uses (p>0.05). Reciproc without use showed higher Sa and Sq when compared to Pro-R without use (p<0.05). No differences were observed between Reciproc and Pro-R after one and two uses (p>0.05). New and unused Reciproc showed longer time to fracture than Pro-R instruments (p<0.05), and only Pro-R showed differences between new and used instruments (p<0.05). Retreatment procedures with Reciproc and Pro-R did not change the surface topography of instruments. Reciproc had greater resistance to cyclic fatigue compared with Pro-R.

Fracture incidence of Reciproc instruments during root canal retreatment performed by postgraduate students: a cross-sectional retrospective clinical study

Objectives

To evaluate the fracture incidence of Reciproc R25 instruments (VDW) used during non-surgical root canal retreatments performed by students in a postgraduate endodontic program.

Materials and Methods

From the analysis of clinical record cards and periapical radiographs of root canal retreatments performed by postgraduate students using the Reciproc R25, a total of 1,016 teeth (2,544 root canals) were selected. The instruments were discarded after a single use. The general incidence of instrument fractures and its frequency was analyzed considering the group of teeth and the root thirds where the fractures occurred. Statistical analysis was performed using the χ² test (p < 0.01).

Results

Seven instruments were separated during the procedures. The percentage of fracture in relation to the number of instrumented canals was 0.27% and 0.68% in relation to the number of instrumented teeth. Four fractures occurred in maxillary molars, 1 in a mandibular molar, 1 in a mandibular premolar and 1 in a maxillary incisor. A greater number of fractures was observed in molars when compared with the number of fractures observed in the other dental groups (p < 0.01). Considering all of the instrument fractures, 71.43% were located in the apical third and 28.57% in the middle third (p < 0.01). One instrument fragment was removed, one bypassed, while in 5 cases, the instrument fragment remained inside the root canal.

Conclusions

The use of Reciproc R25 instruments in root canal retreatments carried out by postgraduate students was associated with a low incidence of fractures.

Defects and Safety of NiTi Root Canal Instruments: A Systematic Review and Meta-Analysis

Aim: To review the reported defect and fracture rates of various NiTi instrumentation systems and identify factors that may influence the chance of NiTi file separation clinically.

Data Sources: PubMed, EMBASE, and SCOPUS with controlled vocabulary and keywords in various combinations to identify articles that reported on the defects and/or fracture of NiTi instrument used clinically (Jan 1980 till Aug 2021), with additional search manually by going through the list of references of the initially screened articles. Those satisfying the inclusion and exclusion criteria were entered into the analysis.

Study Eligibility Criteria, Participants, and Interventions: All studies from the said databases reporting on NiTi root canal instruments that were deformed or separated during normal clinical use.

Study Appraisal and Synthesis Methods: Studies with data available and suitable for meta-analysis were grouped according to the general design of the NiTi instruments for comparison. Safety quotient value was calculated based on the rate of instrument distortion and fracture.

Results: Various instrument designs exhibited different incidences of distortion and fracture, hence a different “safety quotient” (ratio of the amount of deformed instruments to that of fractures in use). Heat-treated files showed the highest safety quotient value. All brands of NiTi file demonstrated a statistically significantly lower incidence of fracture, if treated as disposable instruments after clinical use in a patient.

Limitations: Inclusion of articles written in English only, and grouping of file systems into general design types in the analysis.

Conclusions and Implications of Key Findings: NiTi endodontic files should be scrutinized for defects before being used in the root canal. Disposing the NiTi instruments after clinical use in a patient (so-called “single use”) is recommended for minimizing fracture clinically. Certain instrument designs tend to show discernible deformation before they should fracture in the next use.

Effect of flushing temperature on preparation ability of rotary nickel-titanium files

PURPOSE

The effect of flushing at different temperatures on the preparation ability of rotary nickel-titanium files was investigated to provide guideline for clinical application.

METHODS

Sixty ProTaper Universal F1 rotary nickel-titanium files were randomly divided into three groups treated by flushing at 6°C, 23°C, and 40°C. Root canal preparation was conducted by step-by-step method on standardized nickel-titanium instrument fracture models. During preparation, the thrust force was set as 10 N, and water was continuously flushed. The motor speed was 350 rpm (rounds per minute), and the torque was 3.0 N cm. When the set torque was reached, the motor automatically rotated in the reverse direction and was pulled out.

RESULTS

Root canal preparation was performed using ProTaper Universal F1 rotary nickel-titanium files treated by flushing. The numbers of rotations before the device was fracture were 429.33 ± 214.68, 821.92 ± 410.43, and 1304.92 ± 297.81, respectively. When each root canal was completed, the numbers of instrument rotations were 272.15 ± 88.30, 188.85 ± 34.36, and 163.41 ± 16.18, respectively. Rank sum test and analysis of variance were performed by IBM SPSS Statistics v21.0 software, and both of them were p < 0.01, indicating that the number of cycles to failure (NCF) and the number of instrument rotations for each root tube were statistically different at the three temperatures.

CONCLUSIONS

The self-made resin-simulated curved root canal can replace the real root canal to complete the root canal preparation experiment. The group of nickel-titanium files treated by flushing at 23°C can prepare more root canals and prolong the life of nickel-titanium files than at 6°C. When flushing was done at 40°C, the number of root canals prepared by nickel-titanium files was the highest, and it was not easy to damage the instrument, but lateral perforation occurred easily during root canal preparation.

Cyclic fatigue and torsional resistance evaluation of Reciproc R25 instruments after simulated clinical use

BACKGROUND

To assess the influence of multiple uses on the cyclic flexural fatigue and torsional resistance of Reciproc R25 (REC) instruments.

METHODS

256 canals (2 for each mandibular molar) were prepared using Reciproc R25 instruments. A total of 96 25-mm-long Reciproc R25 instruments were divided in six groups (n=8) on the basis of different number of canal shaped: new instruments (control group), 1, 2, 3, 4 or 6 canals shaped during simulated clinical use for other groups respectively. Sixteen files were used for each of the six groups (8 instruments for cyclic fatigue test and 8 ones for torsional test). Times to fracture (TtF) for cyclic fatigue and ultimate torsional strength and angle of rotation to fracture for torsional resistance were recorded. Data were statistically evaluated by the analysis of variance (ANOVA) with P<.05.

RESULTS

As for cyclic fatigue resistance, there was no significant difference between new REC and REC used in one, two and three canals respectively (P>.05). REC used in four and six canals showed significant lower times to fracture when compared with other groups (P<.05) with REC used in six canals showing the significant lowest times to fracture (P<.05). Considering torsional resistance parameters, no significant difference was observed between the new and used instruments (P>.05).

CONCLUSIONS

REC25 files showed a significant decrease in cyclic fatigue resistance only when used in four or more molar canals while their torsional behavior was not affected by multiple uses.

Design, metallurgical features, mechanical performance and canal preparation of six reciprocating instruments

AIM

To compare six reciprocating instruments regarding their geometric design, metallurgical characteristics, mechanical behaviour and ability to prepare root canals.

METHODOLOGY

A total of 246 new 25-mm NiTi instruments (41 per group) from six reciprocating systems (Reciproc, Reciproc Blue, One Files, One Files Blue, Reverso Silver, and WaveOne Gold) were evaluated throughout a multimethod approach regarding their design using stereomicroscopy (number of blades and helix angle) and scanning electron microscopy (blades symmetry, cross section and surface finishing), nickel-titanium composition, phase transformation temperatures, mechanical performance (cyclic fatigue, torsional and bending resistance) and unprepared canal surface area on anatomically matched mandibular molars assessed by micro-CT. One-way ANOVA and post hoc Tukey's or Mood's median tests were selected depending on sample distribution with significance level set at 5%.

RESULTS

The instruments had similarities regarding their metal composition and unprepared canal area, whilst differences in phase transformation temperatures and geometric design (number of blades, surface finishing and tip geometry) were observed. Overall, no difference was observed regarding the maximum torque values (P > 0.05), whilst One Files (72 s) and One Files Blue (414 s) had the shortest and longest times to fracture, respectively (P < 0.05). Similar angles of rotation were observed in Reciproc (310°), One Files (285°) and Reverso Silver (318°) instruments (P > 0.05), which were significantly lower than Reciproc Blue (492°), One Files Blue (456°) and WaveOne Gold (492°; P < 0.05). Maximum bending load demonstrated that Reciproc Blue (201.3 gf) was significantly more flexible that the other instruments (P < 0.05).

CONCLUSION

Although there were similarities in metal composition and percentage of unprepared canal surface, the instruments had differences in the overall geometric design, phase transformation temperatures and in the four mechanical resistance parameters (time to fracture, maximum torque, angle of rotation and maximum bending load).

Evaluation of usage-induced degradation of different endodontic file systems

To evaluate structural profiles and mechanical behaviour of WaveOne Gold (WOG), Twisted File Adaptive (TFA) and XP-endo shaper (XPS) instruments after root canal preparation. Standardized in vitro shaping was performed in presence of 5.25% sodium hypochlorite. File morphology was analyzed using scanning electron microscopy; X-ray diffraction analysis was performed before and after use along with Raman spectroscopy. Nanoindentation was carried out to characterize surface topography. Ni²⁺ release was measured at 1, 3, 5 and 7 days. X-ray photoelectron spectroscopy (XPS) analysis was done before and after use. After allocating scan line shifts like in WOG, mechanical deformation was shown using first order polynomials. XPS file system showed minimal grooves on surface. SEM of WOG instrument showed scraping surface defects. Hardness varied from 8.11 ± 0.99 GPa in TFA system to 6.7 ± 1.27 GPa and 4.06 ± 4.1 GPa in XPS and WOG. Ni²⁺ concentration from WOG was 171.2 μg/L. Raman peak at 540-545 cm^-1 is attributed to Cr₂O₃. High resolution of Ti 2p spectrum show distinctive peaks with binding energies dominating in WOG, XPS and TFA file system. XRD exhibited NiTi phases with diffraction peaks. WOG files showed more surface deterioration and less passive layer formation as compared to TFA and XPS systems.

Reciproc Endodontic File Surface Defects After Single Use: An SEM Analysis

Objective:

The aim of this investigation was to detect defects that may occur to Reciproc endodontic files after a single use.

Materials and Methods:

A sample of convenience of Reciproc files (VDW GmbH, Munich, Germany) that were used to prepare root canals of anterior or posterior teeth were collected. The files were divided equally into two groups: Group 1 (R25) files were used to prepare mesial root canals of 50 human permanent mandibular molars, and Group 2 (R40) included 50 files that were used to prepare permanent maxillary incisor teeth. Files were analyzed after single use by using a scanning electron microscope at X120 to detect changes in surface morphology. The data were statistically analyzed by using the χ² test, and statistical significance was set at P < 0.05.

Results:

A total of 96 Reciproc NiTi files were collected; of those, 67 (70%) were unaffected and 29 (30%) showed overall surface deformations. The types of deformation were blade disruption (22%), surface pitting (12%), and unwinding and tip deformation (1%). No microcracks were detected, and none of the studied files showed fracture. R40 was three times more likely to be deformed and showed blade disruption compared with R25 (P < 0.05).

Conclusions:

Reciproc rotary NiTi files show high resistance to deformation after a single use. Blade disruption was the most frequent defect occurring in both the small and large files.

Effects of clinical use of NiTi reciprocating instruments on cyclic and torsional resistance, and on roughness

The aim of the present study was to evaluate the cyclic fatigue, torsional resistance and surface roughness of Reciproc R25 instruments in four different situations, namely as new instruments and as instruments tested after clinical preparation of one, two or three maxillary molars with four root canals. The total time required to perform each root canal preparation was recorded. Cyclic fatigue resistance was determined by the time to fracture using a customized testing device (n = 10 per group). The torsional test evaluated the torque and angle of rotation to failure according to ISO 3630-1 (n = 10 per group). The roughness of the working parts of new and used instruments was evaluated with a profilometer (n = 5 per group). Statistical analysis was performed using one-way ANOVA and Tukey's test. The level of significance was set at 5%. No fractures or deformations were observed after clinical use. Higher preparation time was needed during the third use of the instruments for all root canals (p < 0.05). There were no significant differences among the groups in regard to either cyclic fatigue or torsional resistance (p > 0.05). Regarding the roughness measurements, groove depth was higher on new and one- versus two- or three-maxillary-molar-prepared instruments (p < 0.05). It can be concluded that the clinical use of Reciproc instruments increased preparation time and decreased surface roughness. However, clinical use did not affect the cyclic fatigue or torsional resistance of the Reciproc instruments.

Clinical fracture incidence of rotary and reciprocating NiTi files: A systematic review and meta-regression

This systematic review was registered in PROSPERO (CRD42017075917) and aimed to investigate whether the available clinical evidence supports the hypothesis that reciprocating motion results in a lower incidence of nickel-titanium files fracture compared to continuous rotation. Clinical studies that reported the incidence of fracture of engine-driven nickel-titanium files were included. The main exposure was the kinematics, and the primary outcome was the incidence of files fracture. The overall incidence of files fracture was 2.27%, with a trend for higher incidence with rotary motion (2.43%) than with reciprocating (1.0%), though without significant differences. Multiple meta-regression models revealed that the use of nickel-titanium files in more than four teeth and less proficient operators were associated with a higher incidence of file fracture. There was no difference in the clinical incidence of fracture of nickel-titanium instruments between reciprocating and rotary motions; however, other factors were identified.

Safety of large preparation with different instruments in the buccal canals of maxillary molars

This study aimed to evaluate the influence of large apical preparations with Reciproc (REC), Hyflex CM (HCM) and Twisted File Adaptive (TFA) systems using micro-computed tomography (MCT). Ninety mesiobuccal (MB) and distobuccal (DB) root canals of maxillary molars (n = 45) were scanned using MCT before and after the shaping procedures. The root canals (n = 15) were prepared until REC 40.06, HCM 40.04 and TFA 35.04. The root canal transportation (RCT), centring ability (CA), change in volume of the root canal and at different levels (VC), remaining dentine thickness (RDT), removal of dentine wall (RDW) and working time (WT) were evaluated. Data were analysed using the Kruskal-Wallis and Dunn tests, and the one-way ANOVA and Tukey tests with a level of significance set at 5%. No significant difference among the instruments was found regarding the RCT, CA, RDT, RDW and WT (P > 0.05), in larger apical preparations in curved MB and straight DB canals of maxillary molars.

Cyclic fatigue resistance of VDW.ROTATE and Reciproc Blue nickel-titanium files at root canal temperature

Background. This study aimed to compare the VDW.ROTATE instruments with the Reciproc Blue instruments in different kinematics in terms of the cyclic fatigue resistance.

Methods. Sixty instruments, 40 VDW.ROTATE and 20 Reciproc Blue instruments, were divided into three groups (n=20): VDW.ROTATE was used in both continuous rotation and reciprocation, and Reciproc Blue was used in reciprocation only. The cyclic fatigue resistance test was carried out in an artificial canal (60°, r=3 mm) at an intracanal temperature of 35±2°C until fracture, and the time to fracture was recorded in seconds. The data were analyzed statistically using Kruskal–Wallis and Tamhane’s T2 tests (P<0.05).

Results. DAll the reciprocating motion groups resulted in a longer mean duration to failure than the continuous rotation motion group (P<0.05).

Conclusion. It was observed that the Reciproc Blue instruments had higher cyclic fatigue resistance than VDW.ROTATE instruments (P<0.05). Recent studies have shown that reciprocal movement increases cyclic fatigue resistance compared to rotational movement. The VDW.ROTATE instrument, which has a similar size, design, and alloy as the Reciproc Blue instrument, can also be used by clinicians in reciprocating motion with endo motors capable of reciprocating in different directions. However, even if the cyclic fatigue resistance increases by using VDW.ROTATE instruments in reciprocation, the cyclic fatigue resistance is lower than Reciproc Blue instruments.

Quantitative Assessment of the Efficacy of Two Different Single-file Systems in Reducing the Bacterial load in Oval-Shaped Canals: A Clinical Study

INTRODUCTION

This randomized clinical study compared the in vivo antibacterial efficacy of Reciproc Blue (RB), XP-endo Shaper (XP-S), and XP-endo Shaper associated with XP-endo Finisher (XP-F) systems in infected oval-shaped root canals with primary apical periodontitis.

METHODS

In this study, 28 human teeth with a single root and a single canal were randomly assigned to 2 groups according to the instrumentation technique: group 1, RB (n = 14) and group 2, XP-endo (XP-S and XP-F, n = 14). The single-rooted teeth were prepared by reciprocating and rotary nickel-titanium instruments with 5.25% sodium hypochlorite irrigation. Samples were collected from the canal at the baseline (S1), after chemomechanical preparation (S2), and after XP-F instrumentation (S3). The DNA extracts were subjected to quantitative analysis for total bacterial counts by quantitative real-time polymerase chain reaction. The data were analyzed using the analysis of variance test, and the level of significance was set at 5%.

RESULTS

All samples tested positive for the presence of bacteria at baseline, and the bacterial counts substantially reduced after treatment procedures (P < .01). The results showed no statistical difference between RB and XP-S instrumentation with respect to the bacterial reduction (P > .05). A marked bacterial reduction was observed after the use of the XP-F instrument (P < .01).

CONCLUSIONS

The XP-S and RB systems sharply reduced the bacterial load in oval-shaped root canals with primary apical periodontitis. XP-F used as a supplementary instrument to chemomechanical preparation promoted a significantly higher bacterial reduction.

Fracture incidence of WaveOne Gold files: a prospective clinical study

AIM

This prospective clinical study evaluated the incidence of instrument fracture observed after single-file root canal treatment of molars using WaveOne Gold instruments.

METHODOLOGY

Three standardized, experienced and calibrated specialists treated 750 maxillary and mandibular molars with curvatures less than 45° (2691 root canals) over a 12-month period. All the treatments were performed in a single session. A total of 1104 WaveOne Gold instruments were used, including 38 small, 750 primary, 228 medium and 88 large instruments. Intracanal procedures were performed according to the manufacturer's recommendations, and each instrument was used in a single clinical case. The instruments were examined after their removal from the canal, under an operating microscope at 8× magnification.

RESULTS

No fractures were observed in any of the 1104 instruments used.

CONCLUSIONS

No fractures of WaveOne Gold reciprocating instruments occurred during root canal preparations performed in maxillary and mandibular molars with curvatures less than 45° when used strictly according to the manufacturer's recommendations and applied in a single clinical case.

Influence of Negotiation, Glide Path, and Preflaring Procedures on Root Canal Shaping-Terminology, Basic Concepts, and a Systematic Review

INTRODUCTION

Negotiation, glide path, and preflaring are essential steps in root canal shaping procedures. This report aimed to discuss the terminology, basic concepts, and clinical considerations of negotiation, glide path, and preflaring procedures and the influence of these steps on root canal shaping.

METHODS

This systematic review was undertaken following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The protocol has been registered with the International Prospective Register of Systematic Reviews (number CRD42019127021). A comprehensive literature search was performed by 2 independent reviewers using a selected search strategy in 2 electronic databases (PubMed and Scopus) until January 28, 2019. A further search was performed manually in endodontic journals. Studies investigating or comparing at least 1 shaping property resulting from root canal instrumentation with a glide path or preflaring in human extracted teeth or clinical studies were included.

RESULTS

The literature shows that the definition of glide path and preflaring procedures remains controversial, which requires an elaboration in the American Association of Endodontists' Glossary of Endodontic Terms. After the removal of irrelevant and duplicated articles, 98 articles were included. The impact of glide path preparation and preflaring on working length determination, apical file size determination, canal transportation, separation of endodontic files, shaping time, dentinal microcrack formation, and extrusion of debris was discussed. Because of heterogeneity among the included studies, quantitative synthesis was not performed for most of the parameters.

CONCLUSIONS

An evidence-based guideline is needed to define and correlate the basic concepts and current applications of each step of contemporary advancements in root canal instruments. Glide path preparation reduces the risk of debris extrusion, has no influence on the incidence of dentinal crack formation, and improves the preservation of the original canal anatomy. The creation of a glide path may have no impact on Reciproc files (VDW, Munich, Germany) in reaching the full working length. Preflaring increases the accuracy of working length determination. Further randomized clinical trials are required to evaluate the effect of a glide path and preflaring on root canal treatment outcomes.

Surface deformation of several nickel-titanium rotary instruments after removal of the root canal filling materials: a scanning electron microscope evaluation

The aim of the present study was to investigate and compare the surface deformations of different NiTi rotary files after retreatment under scanning electron microscope (SEM). A total of 240 upper central incisor teeth were obturated with vertical compaction technique and divided into 6 groups. Root canals were retreated by ProTaper Next (PTN), Twisted File Adaptive (TFA), Reciproc (RPC), ProTaper Universal Retreatment (PTR), R-Endo and Mtwo-R NiTi rotary systems. The files investigated under SEM at different magnifications and photomicrographs were captured. The photomicrographs were classified and scored. Kruskal-Wallis and Dunn tests were performed for statistical analyze at 5% significance level. PTR and RPC groups were free of defects like file separation, curving and unwinding but PTN and TFA groups showed 50% file separation. According to the photomicrographs that were captured at high magnification; there were no statistically difference between groups at the coronal thirds of the files (P > 0.05), at the middle third PTN and TFA groups showed statistically more deformation than the other groups (P < 0.05). At the apical third Reciproc was statistically showed less deformation than the other all groups (P < 0.05). Within the limitation of this in vitro study, all NiTi files showed surface deformation in SEM observation after retreatment procedures. There was less deformation in PTR and RPC groups according to other.

Torsional behaviour of Reciproc and Reciproc blue instruments associated with their martensitic transformation temperatures

AIM

To compare the martensitic transformation temperatures and torsional resistance behaviour of classic M-Wire Reciproc and Reciproc blue files (VDW, Munich, Germany).

METHODOLOGY

M-Wire classic Reciproc R25 and Reciproc blue R25 instruments were used. Transformation temperatures were determined by differential scanning calorimetry (DSC-DSC 60, Shimadzu, Kyoto, Japan). Three samples with approximately 20 mg of each system were cooled to -120 °C and then heated to 100 °C and then cooled to -100 °C at a rate of 10 °C min^-1 . The maximum torque values and angular deflection until fracture of new instruments (n = 10) were measured according to ISO 3630-1. Results were analysed statistically using the Student's t-test at a significance level of P < 0.05.

RESULTS

DSC results revealed the absence of martensitic transformation for Reciproc instruments in the temperature range analysed. In both systems, the instruments were composed of a mixture of R-phase and austenite at room temperature. After torsional tests, Reciproc blue had significantly lower values for mean maximum torque at rupture (P < 0.05), although the angular deflection values were significantly higher than the Reciproc classic group (P < 0.05).

CONCLUSIONS

Both Reciproc and Reciproc blue instruments were composed of a mixture of R-phase and austenite. Reciproc Blue instruments had a greater angle of rotation to fracture but a lower torque to failure than M-Wire Reciproc instruments.

Evaluation of the usage-induced degradation of Genius and Reciproc nickel-titanium reciprocating instruments

The aim of this study was to characterize the main features and the usage-induced degradation of the Genius file after four severely curved root canal instrumentations and to compare their properties to the Reciproc files. Brand new and ex vivo used files were analysed by scanning electron microscopy (SEM) with energy-dispersive X-ray spectrometry (EDS), differential scanning calorimetry (DSC), X-ray diffraction (XRD), optical metallography, and nano-indentation to disclose their morphological, chemical, mechanical, thermal, and phase composition features. Nano-indentation data were statistically analysed using the Student's t test for normal distribution or the Kolmogorov-Smirnov test for not-normal distributions. SEM analysis showed the presence of micro-cracks near the tip on both files after ex vivo usage test. EDS analysis confirmed that both files are manufactured from an almost equiatomic NiTi alloy. DSC analysis revealed that the transition temperature of the Genius is below 20 °C, while that of the Reciproc is above 20 °C. XRD analysis of Genius files identified cubic B2 austenite with minor peaks of residual monoclinic B19 martensite, while the contemporaneous presence of martensite, austenite and hexagonal R-phase was observed in the Reciproc files. Significant differences in nanohardness and modulus of elasticity (P < .05) were observed in both Genius and Reciproc files before and after use. The collected results showed that both instruments can be safely used as single-use files.

Scanning electron microscopy evaluation of debris and smear layer generated by two instruments used in reciprocating motion WaveOne Gold® and Reciproc Blue®

The aim was to evaluate debris and smear layer at 1, 3 and 5 mm from the foramen of single-file systems WaveOne Gold® and Reciproc Blue®. Thirty single-rooted teeth were prepared using one of the following NiTi instruments WaveOne Gold® and Reciproc Blue®. Root canals were observed under a scanning electron microscope. The presence of debris and smear layer at the apical third of root canals was evaluated. Data were analysed by Friedman and Wilcoxon tests. WaveOne Gold® produced significantly less debris and smear layer compared to Reciproc Blue®. However, the mean amount of debris was significantly different within distances for WaveOne Gold®, while no difference were observed for Reciproc Blue. The mean amount of smear layer was not significantly different within distances with WaveOne Gold® and Reciproc Blue®. Both systems showed debris and smear layer in the apical third; nevertheless, WaveOne Gold® showed better results.

Performance of Reciproc Blue R25 Instruments in Shaping the Canal Space without Glide Path

INTRODUCTION

This study assessed the frequency in which Reciproc Blue R25 instruments (VDW, Munich, Germany) reached the full working length (WL) of mandibular molar canals without a glide path. The influence of the type of electric motor (ie, conventional corded or cordless) on the instrument's performance was also assessed.

METHODS

One hundred mandibular molars with slight to moderate root canals were selected and randomly assigned into 1 of 2 experimental groups according to the type of electric motor used: conventional corded (VDW Silver, VDW) or cordless motors (VDW.CONNECT Drive, VDW). Therefore, 50 molars and 154 root canals were selected for each motor. Reciproc Blue R25 instruments were used until reaching two thirds of the estimated WL. Then, a size 10 K-file was passively inserted to determine the full WL. No active instrumentation movement was performed with a size 10 K-file. Independently, whether a size 10 K-file reached the apex or not, Reciproc Blue R25 instruments were used to complete canal preparation. When the Reciproc Blue R25 instrument was able to reach the full WL, the case was classified as "reaching the full working length" (RFWL). If the instrument was not able to reach the full WL, the case was classified as "not reaching the full working length" (NRFWL). The chi-square test of goodness of fit was used to verify whether the observed frequencies of RFWL and NRFWL adhered to the expected ones. A 5% cutoff level of significance was considered for statistical assumptions.

RESULTS

Reciproc Blue R25 instruments were able to reach the full WL in 304 root canals (98.70%). The chi-square test revealed the observed frequencies of RFWL and NRFWL to be significantly different from the expected frequencies (χ² = 292,208, P = .000). The frequency of RFWL and NRFWL was exactly the same for both types of electric motors. No instrument fractured, and a single file deformed. In 50 of 308 root canals, a size 10 K-file was unable to passively reach the full WL. From these 50 canals, Reciproc Blue R25 instruments were able to reach the full WL in 47 of them.

CONCLUSIONS

Reciproc Blue R25 instruments were able to reach the full WL in a high frequency of cases. The type of electric motor used did not interfere in the frequency of RFWL cases. No instrument fractured, and a single file deformed.

Mechanical Properties of Anatomic Finishing Files: XP-Endo Finisher and XP-Clean

The aim of the present study was to evaluate the cyclic fatigue of two anatomic finishing files: XP-Endo Finisher and XP-Clean. Roughness pattern and the micro-hardness of the files were also assessed. Instruments were subjected to cyclic fatigue resistance measuring the time to fracture in an artificial stainless-steel canal with a 60° angle and a 5-mm radius of curvature. The fracture surface of all fragments was examined with a scanning electron microscope. The roughness of the working parts was quantified by using a profilometer and the micro-hardness test was carried out using a Vickers hardness tester. Results were statistically analyzed using a student´s t-test at a significance level of P < 0.05. Weibull analysis was also performed. XP-Endo Finisher presented significantly longer cyclic fatigue life than XP-Clean instruments (P<0.05). XP-Endo Finisher was able to withstand 1000% more cycles to fracture when compared to XP-Clean instruments. SEM visual inspection of the fracture surfaces revealed fractographic characteristics of ductile fracture in all tested instruments; wide-ranging forms of dimples were identified and no plastic deformation in the helical shaft of the fractured instruments was observed. When mean life was compared XP-Endo Finisher lasted longer than XP-Clean with a probability of 99.9%. XP-Endo Finisher instruments also exhibited significantly lower roughness than XP-Clean instruments (P<0.05). No differences in the micro-hardness was observed between the files (P>0.05). It can be concluded that XP-Endo Finisher instruments showed improved performance when compared with XP-Clean instruments, demonstrating higher cyclic fatigue resistance and lower roughness.

Micro-CT comparison of XP-endo Finisher and passive ultrasonic irrigation as final irrigation protocols on the removal of accumulated hard-tissue debris from oval shaped-canals

OBJECTIVE

To compare the effectiveness of the XP-endo Finisher instrument and passive ultrasonic irrigation (PUI) as final irrigation protocols on the removal of accumulated hard-tissue debris (AHTD) from oval-shaped canals using micro-computed tomographic (micro-CT) analysis.

METHODS

Twenty mandibular incisors were anatomically pair-matched based on similar morphological dimensions (length, volume, aspect ratio, and configuration) through micro-CT analysis, prepared with Reciproc R25 instrument, scanned again, and assigned to one of the two experimental groups (n = 10), according to the final irrigation protocol: XP-endo Finisher and PUI. After the final irrigation protocols, the specimens were rescanned and the registered datasets were examined to quantify the amount of AHTD. Data were statistically analyzed using Student's t test with a significance level of 5%.

RESULTS

The final irrigation protocols were highly similar in terms of volumetric percentage reduction of AHTD (P = 1.000).

CONCLUSIONS

XP-endo Finisher and PUI showed the same effectiveness on the removal of AHTD. None of the tested final irrigation protocols completely removed the AHTD from oval-shaped root canals.

CLINICAL RELEVANCE

AHTD may be considered clinically relevant because it could harbor bacterial contents away from the disinfection procedures. Both final irrigation protocols were effective on the removal of AHTD.

Separation of Nickel-Titanium Rotary and Reciprocating Instruments: A Mini-Review of Clinical Studies

Objective:

This review aimed to evaluate clinical studies that assessed separated NiTi rotary and reciprocating instruments.

Design and Methods:

This review assessed clinical studies involving treatments performed by undergraduate students, graduate students, and endodontic specialists. This review evaluated studies using rotary instruments, reciprocating instruments, and hybrid techniques. The number of uses of the different NiTi rotary and reciprocating systems was also assessed.

Results:

The incidence of separation for rotary instruments ranged from 0% to 23%. Rotary instruments were used from 1 to 50 times depending on the instrument and tooth type. The lowest rate of incidence separation for rotary instruments was obtained by undergraduate students, using a hybrid technique. The separation incidence for reciprocating instruments ranged from 0% to 1.71%. Reciprocating instruments were mostly single-used; one study reported their use up to 3 times. Separation rate in reciprocating instruments was similar in single-use or in multiple uses 0.2%.

Conclusions:

Separation of instruments has dropped recently and seems to be a minor problem in current Endodontics. Multiple uses of NiTi rotary instruments are a possibility without significantly increasing the risk of instrument separation. Single and multiple uses of NiTi reciprocating instruments are also associated with low incidence of separation. Attempting to remove separated instruments should be carefully evaluated.

Fracture incidence of instruments from a single-file reciprocating system by students in an endodontic graduate programme: a cross-sectional retrospective study

AIM

To assess the fracture incidence of instruments from single-file reciprocating systems when used by students in an endodontic graduate programme.

METHODOLOGY

Dental records and periapical radiographs of patients treated by students on an endodontic graduate programme using reciprocating systems were assessed. Data on tooth type, number of treated root canals, number of fractured instruments, fragment size, angle, radius, arc length and position of root canal curvature where fractures occurred were tabulated for analysis. The risk of fracture was calculated for each group of teeth, root canal and root thirds, whilst the incidence of fractures reported for the reciprocating systems was compared using the chi-squared test at 5% significance level.

RESULTS

Overall, 2056 root canals (826 teeth) from 810 patients were included. The incidence of fractured files from single-file reciprocating systems in relation to a number of instrumented canals was 0.92%. Fracture rates of 0.84% and 0.93% were found in 830 and 1226 root canals instrumented with WaveOne and Reciproc systems, respectively. No significant differences were observed between the systems. The highest fracture rate was 52.6% in the mesiobuccal root of mandibular molars. The central angle, radius and arc length of the curvature of root canals where the instruments fractured ranged from 58° to 84°, from 1.7 to 7.2 mm and from 2.4 to 7.6 mm, respectively.

CONCLUSION

The use of WaveOne and Reciproc single-file reciprocating systems in an endodontic graduate programme was associated with a low incidence of instrument fractures.

Topographic and Chemical Analysis of Reciprocating and Rotary Instruments Surface after Continuous Use

This study aimed at evaluating the changes in surface characteristics and NiTi content of reciprocating and rotary instruments after continuous use. Thirty brand-new instruments were assigned to 3 groups (n=10): PNX1 Group - ProTaper Next system - instrument X1; PNX2 Group - ProTaper Next system - instrument X2 and WO Group - WaveOne system - Primary instrument 25.08. The instruments were used to prepare 60 simulated root canals. Analysis of surface characteristics by scanning electron microscopy (SEM) and chemical analysis of Ni and Ti content by energy-dispersive spectroscopy (EDS) were performed before and after the first and third use of the instruments. Only WO Group had significant increase in the quantity of defects and deformations after the third use (p<0.05). PNX1 Group had significant decrease in Ni content after the third use, in comparison with the unused instruments (p<0.05). PNX1 Group had no decrease in Ti content throughout the time of use (p>0.05), however, in PNX2 Group, there was significant decrease in the different time interval of analysis (p<0.05). Continuous use promoted increase in defects and deformations only for WaveOne instruments. Chemical composition presented significant changes according to the time of instruments use.

Bacterial Reduction after Gutta-Percha Removal with Single vs. Multiple Instrument Systems

Introduction:

The aim of this study was to evaluate the effectiveness of a reciprocating single-instrument system (Reciproc-REC) compared with combined continuously rotating multiple-instrument systems [D-Race (DR) and BioRace (BR)] in reducing Enterococcus faecalis (E.f.) after gutta-percha removal.

Methods and Materials:

Forty-six extracted human maxillary incisors were prepared and contaminated with E.f. strain (ATCC 29212) for 30 days. The samples were obturated and randomly divided into two experimental groups for gutta-percha removal (n=23): a REC group (R50) and a DR/BR group (DR1, DR2 and BR6). A standardized irrigation with 0.9% saline solution was performed. Root canal samples were taken with paper points before (S1) and after (S2) the removal of gutta-percha to establish bacterial quantification by culture. The time required for gutta-percha removal was also recorded. Positive and negative control groups (n=6) were used to test bacterial viability and control asepsis, respectively. Data were analysed using t-Student and one-way ANOVA tests (5% margin of error).

Results:

The mean percentage of bacterial reduction was significantly higher in DR/BR group (84.2%) than in REC group (72.3%) (P<0.05). The mean time for obturation removal was 74.00 sec in REC group and 107.53 sec in DR/BR group (P<0.05).

Conclusion:

The combined continuously rotating multiple-instrument system was more effective in reducing bacteria after the removal of gutta-percha than the single-instrument system. None of the tested systems was able to completely eliminate root canal infection after gutta-percha removal. Thus, additional techniques should be considered.

Cyclic Fatigue Life of Two Single File Engine-Driven Systems in Simulated Curved Canals

Introduction:

This study aimed to evaluate the cyclic fatigue resistance of two single file engine-driven instruments, Reciproc and NeoNiTi, in simulated root canals.

Methods and Materials:

Two groups of 15 NiTi endodontic instruments with an identical tip size of 0.25 mm were tested: Reciproc R25 (group A) and NeoNiTi A1 (group B). Cyclic fatigue testing was performed in a stainless steel artificial canal. The simulated canals had a 60^° angle and 5-mm radius curvature. The Reciproc instruments were operated using the preset program on torque control electric motor specific for the Reciproc instruments, while the NeoNiTi instruments were operated using the manufacturer recommendation. All instruments were rotated until fracture occurred, and the number of cycles to fracture (NCF) and the length of the fractured tip were recorded and registered. Means and standard deviations of NCF and fragment length were calculated for each system and data were subjected to Student’s t test (P<0.05).

Results:

A statistically significant difference (P<0.05) was noted between Reciproc and NeoNiTi instruments. NeoNiTi A1 instruments were associated with a significantly higher mean NCF as compared to Reciproc R25 instruments (833±176 vs. 318±87 NCF). There was no significant difference (P>0.05) in the mean length of the fractured fragments between the instruments.

Conclusion:

NeoNiTi instruments were associated with a significantly higher cyclic fatigue resistance than Reciproc instruments.

The effect of root canal preparation on the surface roughness of WaveOne and WaveOne Gold files: atomic force microscopy study

Objectives

To examine the surface topography of intact WaveOne (WO; Dentsply Sirona Endodontics) and WaveOne Gold (WOG; Dentsply Sirona Endodontics) nickel-titanium rotary files and to evaluate the presence of alterations to the surface topography after root canal preparations of severely curved root canals in molar teeth.

Materials and Methods

Forty-eight severely curved canals of extracted molar teeth were divided into 2 groups (n = 24/each group). In group 1, the canals were prepared using WO and in group 2, the canals were prepared using WOG files. After the preparation of 3 root canals, instruments were subjected to atomic force microscopy analysis. Average roughness and root mean square values were chosen to investigate the surface features of endodontic files. The data was analyzed using one-way analysis of variance and post hoc Tamhane's tests at 5% significant level.

Results

The surface roughness values of WO and WOG files significantly changed after use in root canals (p < 0.05). The used WOG files exhibited higher surface roughness change when compared with the used WO files (p < 0.05).

Conclusions

Using WO and WOG Primary files in 3 root canals affected the surface topography of the files. After being used in root canals, the WOG files showed a higher level of surface porosity value than the WO files.

Cyclic Fatigue Resistance of WaveOne Gold, ProDesign R and ProDesign Logic Files in Curved Canals In Vitro

Introduction:

Endodontic instruments are developed to provide a better cleaning of the root canal system and reduce its risk of fracture. The aim of this study was to evaluate the instrumentation time and cyclic fatigue resistance of WaveOne Gold, ProDesign R and ProDesign Logic files.

Methods and Materials:

Thirty Nickel-titanium (NiTi) rotary instruments were divided into 3 groups (n=10). ProDesign Logic file 25/0.06 was used in continuous rotation after glide path preparation. WaveOne Gold 25/0.07 and ProDesign R 25/0.06 files were used in reciprocating motion. Every file instrumented 3 standardized artificial canals. The average time, the number of cycles (NCI) and cyclic fatigue resistance of each file were determined through the number of cycles to failure (NCF) in a stainless-steel device. The total amount of cycles to fracture was also calculated (NCI+NCF). Data was analyzed using the Kruskal-Wallis and Mann-Whitney tests.

Results:

The instrumentation time of the ProDesign Logic file was significantly lower when compared to the other files (P=0.019). The longest times to failure were presented by ProDesign Logic (182.07 sec) and ProDesign R (152.38 sec) files. The same differences were observed for the NCF (910.37 and 761.93). The WaveOne Gold group presented a lower NCF as well as a smaller sum of NCI+NCF (748.33) that was statistically significant when compared to the other groups (P<0.05) respectively.

Conclusion:

The use of continuous rotational motion in canals with a glide path in the ProDesign Logic group led to shorter instrumentation time. The cyclic fatigue resistance of ProDesign R and Logic instruments was superior to WaveOne Gold. The thermal treatment of the instrument’s alloy, its cross section and the glide path seems to influence the cyclic fatigue resistance.

Efficacy of ProTaper NEXT Compared with Reciproc in Removing Obturation Material from Severely Curved Root Canals: A Micro-Computed Tomography Study

INTRODUCTION

The aim of this study was to compare the remaining root canal obturation, volume of dentin removed, and apical transportation after retreatment of severely curved root canals by using Reciproc (REC) or ProTaper NEXT (PTN) systems.

METHODS

Twenty-eight mesial canals of mandibular molars were instrumented and then obturated with gutta-percha and sealer and allocated into 2 balanced groups (n = 14), the REC group (R25 file) and the PTN group (X3 and X2 files). Micro-computed tomography analysis was performed to assess the percentage of residual obturation material, the amount of dentin removed, and apical transportation. The effective time for the removal of obturation and procedural errors were recorded.

RESULTS

Obturation was effectively removed from the root canal in the REC and PTN groups (P ≤ .001), and the percentages of remaining obturation material were similar between both groups (84.8% PTN vs 86.5% REC) (P > .05). The amount of dentin removed (3.17 ± 2.64 mm(3) PTN versus 3.50 ± 2.82 mm(3) REC), apical transportation (at 1 mm: 0.096 ± 0.189 mm PTN versus 0.093 ± 0.186 mm REC; at 3 mm: 0.059 ± 0.069 mm PTN versus 0.082 ± 0.080 mm REC; at 5 mm: 0.097 ± 0.093 mm PTN versus 0.133 ± 0.138 mm REC), and the working time (269.69 ± 19.25 seconds PTN versus 268.62 ± 16.37 seconds REC) were also similar in both groups (P > .05). One file fractured in the REC group.

CONCLUSIONS

Both systems were equally effective in the removal of obturation from severely curved canals and can be used for retreatment. Neither system could completely remove the obturation material; therefore, additional techniques are needed to improve cleaning of the root canal.

Fracture of nickel titanium rotary instrument during root canal treatment and re-treatment: a 5-year retrospective study

AIM

To evaluate retrospectively the incidence of K3 nickel titanium rotary instrument fracture in referred cases during root canal treatment and re-treatment.

METHODOLOGY

Clinical and radiographic reports of 12 867 endodontic cases treated at the King Abdulaziz medical city between January 2010 and November 2015 were reviewed to obtain information on intracanal fractured instruments with respect to the treatment performed, tooth type and the size and at what level the instrument fractured (coronal, middle or apical). The degree of canal curvature was classified into mild (<10^° ), moderate (10-25^° ) or severe (>25^° ). Logistic regression was used to test the incidence of instrument fracture in relation to the root canal treatment performed and tooth type. Chi-square tests were used to analyse the fracture incidence in the treated teeth in respect to fracture level and fractured file diameter. The level of significance was set at 0.05.

RESULTS

Root canal treatment was performed on 8946 cases, whilst re-treatment was performed on 3921 cases. The fracture incidence was higher during re-treatment cases (2.96%) than in primary root canal treatment (0.74%) (P < 0.001) with a 1.41% incidence overall. There was a trend for more fractures in maxillary (1.68%) and mandibular (1.35%) molar teeth. Moreover, 56.6% of the fractured instruments occurred in severely curved canals, and the apical third of the root canal was the most common site for instrument fracture (85.7%), followed by middle (13.2%), and coronal (1.1%) thirds, mostly with file sizes 20 and 25 (59.9% and 25.27%, respectively).

CONCLUSION

The fracture incidence of K3 instruments was significantly greater during root canal re-treatment than root canal treatment, mainly with small instruments and in the apical third of the canals.

The ability of Reciproc instruments to reach full working length without glide path preparation: a clinical retrospective study

Background

Reciproc instruments are the only contemporary root canal instruments where glide path preparation is no longer strictly demanded by the manufacturer. As the complete preparation of root canals is associated with success in endodontic treatment we wanted to assess the ability and find predictors for Reciproc instruments to reach full working length (RFWL) in root canals of maxillary molars in primary root canal treatment (1°RCTx) and retreatment (2°RCTx) cases.

Methods

This retrospective study evaluated 255 endodontic treatment cases of maxillary molars. 180 were 1°RCTx and 75 2°RCTx. All root canals were prepared with Reciproc instruments. The groups were compared and in a binary logistic regression model predictors for RFWL were evaluated.

Results

A total of 926 root canals were treated with Reciproc without glide path preparation. This was possible in 885 canals (95.6%). In 1°RCTx cases 625 of 649 (96.3%) canals were RFWL and in 2°RCTx cases 260 of 277 (93.9%). In second and third mesiobuccal canals (MB2/3) 90 out of 101 (89.1%) were RFWL with Reciproc in 1°RCTx and in the 2°RCTx treatment group 49 out of 51 cases (96.1%). In mesio-buccal (MB1) canals “2°RCTx” was identified as negative predictor for RFWL (OR 0.24 (CI [0.08–0.77])). In MB2/3 canals full working length was reached less often (OR 0.04 (CI [0.01–0.31])) if the tooth was constricted and more often if MB2/3 and MB1 canals were convergent (OR 4.60 (CI [1.07–19.61])).

Discussion

Using Reciproc instruments, the vast majority of root canals in primary treatment and retreatment cases can be prepared without glide path preparation.

Intraoperative discomfort associated with the use of a rotary or reciprocating system: a prospective randomized clinical trial

Objectives

The aim of this randomized, controlled, prospective clinical study was to evaluate patients' intraoperative discomfort during root canal preparations in which either multi-file rotary (Mtwo) or single-file reciprocating (Reciproc) systems were used.

Materials and Methods

Fifty-five adult patients, aged between 25 and 69 years old, with irreversible pulpitis or pulp necrosis participated in this study. Either the mesiobuccal or the distobuccal canals for maxillary molars and either the mesiobuccal or the mesiolingual canals for mandibular molars were randomly chosen to be instrumented with Mtwo multi-file rotary or Reciproc single-file reciprocating systems. Immediately after each canal instrumentation under anesthesia, patient discomfort was assessed using a 1 - 10 visual analog scale (VAS), ranging from ‘least possible discomfort’ (1) to ‘greatest possible discomfort’ (10). The Wilcoxon signed-rank test was used to determine significant differences at p< 0.05.

Results

Little intraoperative discomfort was found in all cases. No statistically significant differences in intraoperative discomfort between the 2 systems were found (p = 0.660).

Conclusions

Root canal preparation with multi-file rotary or single-file reciprocating systems had similar and minimal effects on patients' intraoperative discomfort.

Fracture Incidence of WaveOne and Reciproc Files during Root Canal Preparation of up to 3 Posterior Teeth: A Prospective Clinical Study

INTRODUCTION

Reciprocating instruments were developed to improve and simplify the preparation of the root canal system by allowing greater centralization of the canal and requiring a shorter learning curve. Despite the risk of instrument separation, using a reciprocating instrument in more than 1 case is a relatively common clinical practice. The aim of this study was to evaluate the fracture resistance of Reciproc (R25; VDW, Munich, Germany) and WaveOne (Primary; Dentsply Maillefer, Ballaigues, Switzerland) instruments according to the number of uses during the preparation of root canals in up to 3 posterior teeth.

METHODS

A prospective clinical study was conducted by 3 experienced specialists who performed treatment of 358 posterior teeth (1130 canals) over a period of 12 months using 120 reciprocating instruments, 60 of which were Reciproc R25 and 60 were WaveOne Primary. The motion used during instrumentation followed the recommendations of the respective manufacturers. After each use, the instruments were observed under a dental operating microscope at 8× magnification. In the case of fracture or deformation, the instrument was discarded.

RESULTS

None of the instruments showed any signs of deformation, but 3 instruments fractured (0.26% of the number of canals and 0.84% of the number of teeth). All fractures occurred in mandibular molars (1 WaveOne Primary file during the third use and 2 Reciproc R25 files, 1 during the first use and the other during the third use).

CONCLUSIONS

There was a low incidence of fracture when reciprocating files were used in up to 3 cases of endodontic treatment in posterior teeth.