Fatigue in rotary endodontic instruments -A review (original) (raw)
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Restorative Dentistry & Endodontics
Objectives: To compare the flexural cyclic fatigue resistance and the length of the fractured segments (FLs) of recently introduced M-Pro rotary files with that of RaCe rotary files in curved canals and to evaluate the fracture surface by scanning electron microscopy (SEM). Materials and Methods: Thirty-six endodontic files with the same tip size and taper (size 25, 0.06 taper) were used. The samples were classified into 2 groups (n = 18): the M-Pro group (M-Pro IMD) and the RaCe group (FKG). A custom-made simulated canal model was fabricated to evaluate the total number of cycles to failure and the FL. SEM was used to examine the fracture surfaces of the fragmented segments. The data were statistically analyzed and comparisons between the 2 groups for normally distributed numerical variables were carried out using the independent Student's t-test. A p value less than 0.05 was considered to indicate statistical significance. Results: The M-Pro group showed significantly higher resistance to flexural cyclic fatigue than the RaCe group (p < 0.05), but there was no significant difference in the FLs between the 2 groups (p ≥ 0.05). Conclusions: Thermal treatment of nickel-titanium instruments can improve the flexural cyclic fatigue resistance of rotary endodontic files, and the M-Pro rotary system seems to be a promising rotary endodontic file.
SEM study of simulated clinical use for four nickel–titanium rotary endodontic files
MEDICAL DEVICES & SENSORS, 2019
Nickel-titanium (NiTi) rotary endodontic instruments are the major medical devices currently used for root canal therapy. Recently marketed NiTi files are manufactured using thermomechanical processes that improve fatigue resistance and flexibility, which are critical for clinical performance. This study employed a simulated clinical model to compare the wear and fracture of three such rotary instrument products (ProFile Vortex Blue™, ProTaper Gold™ and Coltene HyFlex ® CM™), with a previously introduced product (ProFile Vortex™) serving as a control. Files were examined by scanning electron microscope (SEM) at four positions along their length before use and through three simulated clinical procedures on extracted teeth. Wear and deformation How to cite this article: Burke Jr. T, Nusstein J, Drum M, Fowler S, Brantley WA, Draper J. SEM study of simulated clinical use for four nickel-titanium rotary endodontic files.
Materials Science and Engineering: C, 2014
The aim of this paper is to analyze the cyclic performance of two different Ni-Ti endodontic rotary files made from different alloys under bending using Finite Element Analysis (FEA). When experimentation is not available, this is not a trivial task and most papers on the subject rely on static analysis only. Two Ni-Ti rotary instruments are selected, ProFile GT and a GT Series X (GTX). The latter file is made from M-Wire, which has been thermo-mechanically processed to have larger flexibility, according to its manufacturer. The mechanical response was studied by considering different scenarios in the FEA package, in which the material properties were introduced according to existing literature. The method and results are presented and discussed so that this paper can be used as a guideline for future works. Although not fully reflective of the instrument's behavior in a dynamic rotation intra-canal system, the models used constitute a good approximation when a comparison between two instruments is at stake. It is shown that the GTX file has a lower risk of fatigue fracture during
Materials, 2022
The current study aimed to compare the F1 endodontic instruments from five different heat-treated rotary systems regarding their design, metallurgical properties, and mechanical performance. Five F1 root canal shaping instruments (ProTaper Gold [PTG], Premium Taper Gold, Go-Taper Flex, EdgeTaper Platinum, and Super Files Blue)—plus, a conventional ProTaper Universal (PTU)—which were evaluated regarding their design, nickel/titanium ratio, phase transformation temperatures, microhardness, cyclic fatigue, and torsional and bending strengths. Mood's median test was used for the statistical comparison with a significance set at 5%. The instruments were similar regarding the nickel/titanium ratio and overall design. Go-Taper Flex had the closest transformation temperatures to PTG. PTU and Go-Taper Flex had the highest microhardness (408.3 and 410.5 HVN). The time to fracture of Super Files Blue was three and seven times higher than PTG and PTU, respectively. No difference was observe...
Aim: This study compared the mechanical properties of Profile Vortex, Profile Vortex Blue, and Race rotary files. Materials and Methods: The files were subjected to flexibility, rotating-bending (static and dynamic), and torsional resistance tests. Results: Analysis of the data obtained was performed using ANOVA and Student-Newman-Keuls tests. Significant difference in flexibility was observed between Profile Vortex Blue and the two other files tested (Profile Vortex M Wire and Race) (P<0.05); however, Profile Vortex M Wire and Race did not significantly differ from each other (P>0.05). In the rotatingbending tests (static and dynamic), Profile Vortex Blue presented significantly greater resistance than Profile Vortex M Wire and Race (P<0.05). As for the torsional resistance test, Profile Vortex M Wire had significantly greater resistance (degrees and turns) than the other two instruments tested (P<0.05). No difference in torsional resistance was observed between Profile Vortex Blue and Race files (P>0.05). Statistical analysis revealed significant differences in maximum torque among the instruments tested, as follows (in decreasing order): Profile Vortex Blue > Profile Vortex M Wire > Race (P<0.05). Conclusion: Profile Vortex Blue files were more flexible, more resistant to rotating-bending fatigue, and to torsional failure when compared to Profile Vortex (made of M-Wire NiTi) and Race files (made of conventional NiTi)
Rotary files with superelastic qualities have received attention in dentistry field with gold standard for endodontic procedures such as root canal preparation and shaping. Despite their high flexibility, files within root canals can fracture. The most common causes of file fractures are bending and torsional forces. Therefore, manufacturers attempt to enhance the mechanical properties in order to resist such forces and pressures. Many factors, including the instrument-making process, alloy's characteristics, as well as file geometry and features like pitch length and taper may impact the mechanical performance of the files. The aim of the present study was to investigate the effect of file geometry on file resistance to flexural and torsional stresses. This work was conducted as an experimental analysis using finite element analysis (FEA). The NiTi file was characterized using X-ray diffraction (XRD) analysis. Four different endodontic files including Vortex Blue, Edge File, One Curve and Hyflex-EDM with the same tip and diameter, and different geometric features were designed using SolidWorks software. These models were then transferred to ANSYS, a three-dimensional (3D) modeling program, and examined under torsional and flexural forces. In order to simulate rotational stress, the file shank was fixed and rotated at θ = 22°. In additon, a 3.8 mm file was bent on the Y axis for simulating flexural stresses. The Edge File and Vortex Blue file had the highest and lowest amounts of flexural and torsional stress, respectively. Further, in all the samples the highest amount of torsional stress was observed at 2 to 3 mm of the file tip while the highest amount of flexural stress was seen in the depth of the flutes and near the winning edges. The four examined endodontic instruments had different mechanical properties due to their different geometry. For a good and longer-lasting root canal treatment, dentists should utilize an appropriate file based on manufacturing instructions and clinical conditions.
An In Vitro Cyclic Fatigue Analysis of Different Endodontic Nickel-Titanium Rotary Instruments
Journal of Endodontics, 2012
Introduction: The study compared Twisted File (TF) with 3 traditionally manufactured systems to determine whether changes in the manufacturing process improved the cyclic fatigue resistance. Methods: Four rotary file systems, (1) ProFile (PF), (2) Mtwo, (3) K3, and (4) TF, were tested in artificial canals with 45 and 90 angles of curvature. Ten instruments each of the 4 file systems were tested in both angles of curvature (n = 10). All instruments had identical size and taper (.06/0.25 tip diameter). Results: A statistically significant difference (P < .05) was noted between TF and other nickel-titanium instruments in both 45 and 90 angles of curvature. TF showed the greatest mean number of cycles to failure. There was no statistical difference between PF and K3 (P > .05) in both canal curvatures; however, statistically significant difference (P < .05) was observed between Mtwo and the other 2 traditionally manufactured instruments. Mtwo showed the lowest mean number of cycles to failure. Conclusions: Under the conditions of this study, size .06/0.25 TF was significantly more resistant to fatigue than the other 3 instrument systems produced with the traditional grinding process.