Rotary Nickel-titanium Research Articles

Impact of Angle of File Access and Location of Canal Curvature on the Dynamic Cyclic Fatigue of Nickel Titanium Rotary Instruments.

To evaluate the impact of different file access angles and root canal curvature's location on the fatigue failure of One Curve (OC) and E3 Azure (EZ) NiTi files using a dynamic model at simulated body temperature. Eighty new instruments with similar tip sizes and taper (#25/0.06) from two NiTi rotary systems, One Curve and E3 Azure, were tested at simulated body temperatures (37°C) using a custom-made dynamic cyclic fatigue device. Instruments were divided into four subgroups according to the location of root canal curvature (a coronal curve 5 mm from the root canal orifice and an apical curve 10 mm from the root canal orifice) and the angle of file access (0° or 30°). Instruments were operated in simulated stainless-steel canals having a 60° curve and a 3 mm radius. A custom-made device produced controlled vertical pecks during file rotation. Time to failure (sec) was registered, and the length of the fragment segments was measured (mm). Data were analysed statistically with One-Way ANOVA and Tukey post hoc tests. The significance level was set at 5%. All separated instruments were examined by scanning electron microscope. One-way ANOVA (p<0.05) found a significant difference among the tested instruments. Post Hoc analysis revealed lower cyclic fatigue resistance when the angle of file access was 30º, and the root canal curvature was located coronally for both files (p<0.0001). Three-way ANOVA showed that the angle of file access was the most influential contributor to cyclic fatigue, followed by the location of file curvature and, finally, the file type (p<0.0001). The fractographic examination revealed a predominantly ductile fracture mode for all tested instruments. The lengths of all fractured segments showed no significant difference (p>0.05), indicating an accurate trajectory during testing. OC files had superior cyclic fatigue resistance than EZ files; coronal curvatures negatively impacted cyclic fatigue resistance compared to apical curvatures, while the angle of file access presented the highest impact on dynamic cyclic fatigue.

The Effect of the Conservative versus the Traditional Access cavity on microhardness of Nickel Titanium Rotary Files

The Effect of the Conservative versus the Traditional Access cavity on microhardness of Nickel Titanium Rotary Files

Shaping Ability of Novel Nickel-Titanium Rotary Instruments Manufactured With Different Thermal Treatments

Shaping Ability of Novel Nickel-Titanium Rotary Instruments Manufactured With Different Thermal Treatments

Shaping Ability of a Novel Rotary Nickel Titanium System using Cone Beam Computed Tomography (An Invitro Study)

Shaping Ability of a Novel Rotary Nickel Titanium System using Cone Beam Computed Tomography (An Invitro Study)

The Incidence Of Dentinal Micro-Cracks Associated With Root Canal Preparation With Different Nickel Titanium Rotary Systems: An In-Vitro Study

The Incidence Of Dentinal Micro-Cracks Associated With Root Canal Preparation With Different Nickel Titanium Rotary Systems: An In-Vitro Study

Implementing rotary root canal instrumentation in the clinical training of undergraduate students from Saudi Dental Schools: A cross-sectional survey

Introduction: Rotary nickel–titanium files for root canal therapy have become standard treatment modalities in general practice and specialized dental centers. Undergraduate dental students should receive proper training in using rotary files before graduation. Therefore, this study aimed to provide detailed insight into the implementation of rotary root canal instruments in the clinical training of undergraduate students in Saudi Arabia. Materials and Methods: Two randomly selected private schools and 13 government-owned schools were selected to represent all administrative regions in Saudi Arabia. The SurveyMonkey® questionnaire was sent to each dental school through direct communication. It covered most aspects of the rotary root canal instruments used in the clinical training of undergraduate students before graduation. Results: Approximately 92.9% of the included dental schools reported using rotary files in undergraduate teaching; however, only 57.1% had specific clinical requirements for rotary root canal instrumentation in their curricula. Laboratory simulation sessions were the most commonly used preclinical training methods for rotary instrumentation (85.7%). Most dental schools implemented rotary file training in the 4th and 5th years (53.8% and 38.5%, respectively). The ProTaper® (Universal, Next, Gold) was the most commonly used rotary system. Most dental schools had an instructor-to-student ratio of 1:5. Conclusion: Most Saudi dental schools have adopted rotary files during their undergraduate training. However, the curricula of some dental schools do not include a predetermined number of clinical cases treated with rotary instrumentation to ensure better training for students before graduation.

Finite Element Analysis of the Mechanical Behaviors of Endodontic Nickel–Titanium Rotary Files: A Review

Finite Element Analysis of the Mechanical Behaviors of Endodontic Nickel–Titanium Rotary Files: A Review

Comparison of Different Rotary Nickel–titanium Systems to Evaluate Coronal Leakage of Root Canals: An in Vitro Study

Introduction: The objective of the study was to assess coronal leakage following root canal treatment utilizing four Micro Mega rotary nickel–titanium files, specifically One shape, Two shape (s1), Two shape (s2), and Revo-S, by means of dye penetration analysis using a stereomicroscope set at 20× magnification. Methods: Fifty human lower premolar teeth that were extracted for orthodontic reasons were included in the study, excluding teeth with cracks, caries, severe curvature (&lt;25°), or root resorption. The teeth were randomly assigned to five groups using www.random.org, and standard endodontic treatments were performed as per the manufacturer’s instructions using Micro Mega One shape, Two shape (s1), Two shape (s2), and Revo-S rotary nickel–titanium systems. To measure dye penetration, the teeth were immersed in a 2% methylene blue dye solution for approximately 24 hours and then axially split using a diamond sectioning disc, with measurements taken using a stereomicroscope. Results: The study groups showed statistically significant differences (P &lt; 0.001), and all pairwise comparisons were found to be significantly different according to the post hoc test (P &lt; 0.001). Conclusion: Our results showed that various rotary file designs significantly affect coronal leakage.

Loss of working length in curved canals with rotary nickel–titanium instruments and reciprocating files

ABSTRACT Aim: The aim of the study was to investigate the change of working length in curved molar root canals after preparation with rotary nickel–titanium instruments and reciprocating files. Materials and Methods: Thirty human-extracted maxillary and mandibular molars with curved roots were selected, with the help of a radiographic platform, a constant object sensor distance was arranged to take a digital radiograph of each tooth for determining the angle of curvature of the roots by Schneider’s method. The teeth were divided into Groups I, II, and III based on the instrumentation, ProTaper group, Reciproc group, and control group, respectively. Preoperative and postoperative working length was determined and compared using cone-beam computed tomography. The difference was determined statistically using one-way anova analysis. Results: There was minimum loss of working length found when instrumentation was done with Reciproc files compared with ProTaper. Conclusion: Reciprocating instruments can be an effective alternative used in the preparation of severely curved canals.

Effect of two thermally-treated rotary nickel-titanium files with and without root canal filling on fracture resistance of teeth, an ex-vivo study.

Effect of two thermally-treated rotary nickel-titanium files with and without root canal filling on fracture resistance of teeth, an ex-vivo study.

Comparative Evaluation of a Dynamic Navigation System versus a Three-dimensional Microscope in Retrieving Separated Endodontic Files: An In Vitro Study

IntroductionThis study aimed to compare the effectiveness of a dynamic navigation system and a three-dimensional microscope in retrieving broken rotary Nickel-Titanium files when using trepan burs and the extractor system. Materials and MethodsThirty maxillary first bicuspids with 60 separate roots were split into 2 comparable groups based on a comprehensive cone beam computed tomography analysis of the root length and curvature. After standardized access opening, glide paths, and patency attainment with the K file (sizes 10 and 15), the teeth were arranged on 3D models (three per quadrant, six per model). Subsequently, controlled-memory heat-treated Nickel-Titanium rotary files (#25/0.04) were notched 4 mm from the tips and fractured at the apical third of the roots. The C-FR1 Endo file removal system was employed under both guidance to retrieve the fragments, and the success rate, canal aberration, treatment time, and volumetric changes were measured. The statistical analysis was performed using IBM SPSS software at a significance level of 0.05. ResultsThe microscope-guided group had a higher success rate than the dynamic navigation system guidance, but the difference was insignificant (P > .05). In addition, the microscope-guided drills resulted in a substantially lower proportion of canal aberration, shorter time to retrieve the fragments and less change in the root canal volume (P < .05). ConclusionAlthough dynamically guided trephining with the extractor can retrieve separated instruments, it is inferior to three-dimensional microscope guidance regarding treatment time, procedural errors, and volume change.

A critical evaluation of physical and manufacturing properties of genuine and counterfeit rotary nickel-titanium endodontic instruments.

Rotary nickel-titanium (NiTi) instruments are made to exacting standards and are costly to manufacture, and quality control is paramount. Consequently, unauthorized factories make counterfeit instruments that are less expensive and may therefore be attractive to dentists. Little information exists about the metallurgy and manufacturing quality of such instruments. There is the potential for counterfeit instruments to be at higher risk of fracture during treatment, thereby compromising clinical outcomes. The aim of this study was to evaluate physical and manufacturing properties of genuine and counterfeit ProTaper Next™ and Mtwo® rotary NiTi instruments. This study investigated the metallurgical properties, manufacturing quality, microhardness and number of cycles to failure of two commonly used rotary NiTi systems and compared them with counterfeit products purporting to be genuine articles. Counterfeit instruments were found to be inferior in manufacturing standards and were less resistant to cyclic fatigue when compared to genuine instruments. Counterfeit rotary NiTi instruments may be less efficient at preparing root canals and may be at higher risk of fracture during endodontic treatment. Dentists must be aware that, although less expensive, counterfeit instruments may be of dubious manufacturing quality and at higher risk of fracture if used in patients. © 2023 Australian Dental Association.

Evaluation of cyclic fatigue resistance of nickel titanium rotary instruments: A systematic review and meta- analysis

A number of different thermomechanical treatments of NiTi have been developed to overcome some of the drawbacks of the traditional NiTi alloy, namely, separation and distortion of instruments. The present study analyzes the data on nickel-titanium instruments and their cyclic fatigue resistance. Online electronic data base such as PubMed, Cochrane and Google scholar through 31 January 2000 to 31 January 2020 with only English language literature. Clinical study of 9 article review &amp; stated that the Cyclic Fatigue Resistance Of Nickel Titanium Rotary Instruments tested in artificial blocks or canals ,tested with different NiTi rotary files between 200-500 rpm and accordingly torque under controled/uncntroled temperature in curved canls fracture occure. The findings of this systematic review and meta-analysis point to the possibility that the temperature at which the instruments are tested may affect the results of cyclic fatigue resistance on NiTi files with a different behavior depending on the heat treatment of the alloy and that an increase in the angle of curvature of artificial canals has a detrimental effect on the cyclic fatigue resistance. Reciprocal movement exhibited the best performance with regard to cyclic fatigue resistance. The thermal treatment of the instrument’s alloy, its cross section, and the glide path seem to influence the cyclic fatigue resistance. The cyclic fatigue resistance of instruments manufactured with the gold heat treatment is not influenced by room or intracanal temperature.

The Effect of the Conservative versus the Traditional Access Preparation on Nickel Titanium Rotary Files

The Effect of the Conservative versus the Traditional Access Preparation on Nickel Titanium Rotary Files

Effect from Autoclave Sterilization and Usage on the Fracture Resistance of Heat-Treated Nickel–Titanium Rotary Files

This study aimed to assess the effect of mechanical loading and heating on the cyclic fatigue and torsional fracture resistances of heat-treated nickel-titanium files after usage and autoclaving. Sixty files (One Curve) were tested for cyclic fatigue and torsional fracture resistances using customized devices. The files were divided into three groups according to the test conditions (n = 10); new (group-N), used for simulated canal shaping (group-U), and sterilized after use (group-S). For cyclic fatigue resistances, the files were freely rotated in a curved metal canal under body temperature; the time elapsed to fracture was recorded and the numbers of cycles to fracture (NCF) were calculated. For the torsional resistances, the file tip was fixed and rotated until the file fractured. The maximum torsional load and distortion angle were recorded. The toughness was calculated. Fracture fragments were examined with a scanning electron microscope. Data were analyzed using a one-way analysis of variance and Tukey's post hoc test at the significance level of 95%. Group-U showed significantly higher NCF than group-S (p < 0.05). However, there was no significant differences between groups-N and -S in the NCF (p > 0.05). Group-N showed a significantly bigger distortional angle and higher torsional toughness than groups-U and -S, but the ultimate torsional strength did not have significant difference between the groups. Under the limitation of this study, autoclave sterilization after single-usage did not improve the fracture resistance of heat-treated One Curve nickel-titanium files.

Static and Dynamic Cyclic Fatigue Resistance of Nickel-Titanium Rotary Instruments in a Double-Curved Stainless Steel Artificial Canal

The present study aims to measure the number of cycles leading to fracture (NCF) of instruments in static and dynamic cyclic fatigue situations under body temperature in stainless steel double-curved canals. The framework was constructed to establish the movement of instruments occurring at a stable body temperature. A step motor, a holding system for an endodontic handpiece, created the movement in and out of the artificial canal of the file mounted on the handpiece. A total of 30 instruments of ProTaper Universal and ProTaper Next (Dentsply Sirona, Maillefer, Ballaigues, Switzerland) were divided into three groups of 10 per group. For group 1 (10 PTU F2), files were rotated in static cycles. For groups 2 (10 PTU F2) and 3 (10 PTN X2), files were rotated in dynamic cycles. Files were rotated using proprietary programs, and the times the files were rotated before fracture were recorded. Data were analyzed using survival probabilities and regression with life data. The ProTaper Next in the dynamic cycles had the largest NCF, and the ProTaper Universal in the static condition had the least. New modes of rotation, material, and design have affected the cyclic fatigue resistance of the instrument.

Evaluation of postoperative pain with new heat-treated rotary and reciprocating nickel-titanium files: A randomized controlled clinical trial.

A special heat-treated endodontic file (TruNatomy) was recently introduced with the claim of superior flexibility to enhance dentin preservation. The aim of the present study was to assess postoperative pain in single-visit root canal treatment with this newly introduced file, comparing it with other contemporary reciprocating and rotary file systems. One hundred seventy patients with acute irreversible pulpitis in maxillary premolars were randomly assigned to four experimental file systems: TruNatomy, HyFlex EDM, EdgeFile, and ProTaper Gold. Pre- and postoperative pain scores were assessed with 10-point visual analog scale. Data were statistically analyzed using Kruskal-Wallis test. TruNatomy file system had significantly the highest postoperative pain incidence (53.8%), while the EdgeFile system had significantly the least postoperative pain incidence (24%) and 24-h pain score. The present study demonstrated that the reciprocating multiple-file system, EdgeFile, had significantly reduced postoperative pain incidence compared to other heat-treated rotary nickel-titanium file systems.

Negotiability of mesiobuccal canals in maxillary first molars using different path file systems

Background: In endodontics, glide path creation has been extensively considered a mandatory clinical step to improve the safety and efficiency of rotary nickel–titanium instruments. The high anatomic variations in the mesiobuccal (MB) root of the maxillary molars are observed in the form of canal configuration, number, and position.The aim of this study was to evaluate the negotiability of MB canals in maxillary molars using different pathfiling systems (ProGlider, R-pilot, HyFlex electrical discharge machining [EDM], WaveOne Gold Glider, and C-Pilot).Materials and Methods: This in vitro study included 125 maxillary first molars with closed apex. Before preparation, all teeth were scanned by periapical radiograph for review of the presence of second MB (MB2) canals, without any resorption or calcification, and moderate curve of MB root canal. Subsequently, the access cavity was prepared with a Diamond Fissure Bur. Then, the samples were divided into five groups (ProGlider, R-pilot, HyFlex EDM, WaveOne Gold Glider, and C-Pilot). Certain relevant indices were recorded for analysis, such as the negotiability of the glide path file in the MB canals, file fracture rate, and negotiation speed. The level of significance P value was set at 0.05.Results: In this study, HyFlex EDM was the only path file that could not reach the full working length (WL) in some cases. The highest frequency of file fracture in the MB2 was observed with HyFlex EDM (24%); nevertheless, R-Pilot presented an intermediate fracture rate (16%), and both ProGlider and WaveOne Gold Glider were the safest files (4%) in this regard. However, there were no significant differences between the groups (P = 0.065). The lowest and the highest average time of reaching full WL was observed with WaveOne Gold Glider and HyFlex EDM; nonetheless, there was no significant difference between the four rotary groups. The average number of pecks in HyFlex EDM was significantly higher in comparison to those reported for WaveOne Gold Glider and ProGlider.Conclusion: Path files used for glide path preparation in the MB2 canals of maxillary molars should be flexible with low taper. The use of HyFlex EDM in the MB2 canals is not recommended due to its high taper.

Evaluation of Intracanal Smear Layer Removal after Passive Microvolume Irrigation with Sodium Hypochlorite and Rotary NickelTitanium Instruments: An In-vitro Study

Introduction: Passive Microvolume Irrigation (PMI) with Sodium Hypochlorite (NaOCl) has been proposed as a new method for root canal disinfection. It is based on the concept that irregular surface characteristics of endodontic instruments can carry NaOCl into the canal space with controlled fluid volume, without applying any pressure. Aim: To compare and evaluate the efficacy of 3% and 5% NaOCl PMI, Saline PMI, and 3% NaOCl Standard Irrigation (SI) in removing the Smear Layer (SL) from the root canal walls at the cervical, middle, and apical thirds of single-rooted teeth. Materials and Methods: This study was conducted in the Department of Conservative Dentistry and Endodontics at Vishnu Dental College, Andhra Pradesh, India. The study was conducted in February 2018. Forty maxillary central incisors with a single canal, extracted within three months of the study, were collected. The teeth were divided into four groups (n=10) based on the irrigation method: Group-1 (3.0% NaOCl SI), Group-2 (3.0% NaOCl PMI), Group-3 (5.0% NaOCl PMI), and Group-4 (Saline PMI). All samples were instrumented upto F4 size with Protaper rotary files, and a final rinse of 17% Ethylenediaminetetraacetic Acid (EDTA) was used. SL removal was evaluated using Scanning Electron Microscope (SEM). The data were analysed using Statistical Package for Social Sciences (SPSS) 21.0. Statistical tests used were Kruskal Wallis and Mann-Whitney-U tests. A p-value of &lt;0.05 was considered statistically significant for all comparisons. Results: There was no significant difference (p&gt;0.05) in SL removal between 3.0% NaOCl SI, 3.0% NaOCl PMI, and 5.0% NaOCl PMI in the middle and apical thirds of the root canals. However, 5.0% NaOCl PMI showed significantly higher efficiency in SL removal at the cervical third compared to the other groups (p&lt;0.05). Conclusion: Passive microvolume irrigation with 3% and 5% NaOCl showed comparable efficacy to 3% hypochlorite SI in the middle and apical thirds of the root canal.

Effect of autoclave sterilization on the cyclic fatigue resistance of EdgeFile X7, 2Shape, and F-one nickel-titanium endodontic instruments.

Rotary nickel-titanium files have become the most commonly used engine-powered endodontic instruments due to their improvement in fatigue resistance and flexibility. The autoclaving is the most commonly used method for sterilization. However, the risk of instrument fracture, mainly due to cyclic fatigue during rotation within a curved canal, is still a matter of critical concern. This study aimed to measure and compares the cyclic fatigue resistance of EdgeFile X7, 2Shape, and F-One files in a single curved simulated canal before and after autoclave sterilization. Twenty-four files each of EdgeFile X7, 2Shape, and F-One files were used in this study. They were grouped as group A: EdgeFile X7, group B: 2Shape, and group C: F-One files. Then, each group was subdivided into two, sterilized and nonsterilized, subgroups. The files were tested using a custom-made artificial canal. The number of cycles to fracture (NCF) was calculated. One-way analysis of variance, post hoc Tukey's test, and independent t-test were used. In nonsterilized instruments, the NCF of the EdgeFile X7 group was significantly higher than that in the other groups (P < 0.05). In sterilized instruments, there was a nonsignificant difference in NCF between EdgeFile X7 and F-One files (P > 0.05). The NCF of 2Shape was significantly lower than other files (P ≤ 0.05) in sterilized and nonsterilized groups. The autoclaving significantly decreased (P ≤ 0.05) the cyclic fatigue resistance of the tested files. EdgeFile X7 was the most fatigue resistant. Autoclaving reduced the cyclic fatigue resistance of the tested files.