Analyzing Surface Morphology Changes Induced by Cyclic Fatigue in Three Different Nickel-Titanium Rotary Files Using Scanning Electron Microscopy Analysis.

Jain, Mahima P.; Thumar, Sweety M.; Dave, Jay H.; Joshi, Chintan; Bhatt, Applu R.; Dholani, Juhi I.

Aim: Preparing extreme canal curvatures poses a significant challenge. The objective of this research is to conduct a comparative analysis of the cyclic fatigue resistance among three different nickel-titanium (NiTi) rotary files followed by evaluation of the surface through scanning electron microscopy (SEM). Materials and methods: A total of 30 NiTi endodontic rotary files were utilized and divided into three groups, with each group containing 10 files. Group A consisted of Flexer Trio files, group B included ProTaper Gold files, and group C comprised HyFlex CM files. These files had a tip size of 0.25 mm, taper of 6%, and a length of 25 mm. To assess cyclic fatigue, a custom experimental setup was employed. The NiTi files were subjected to rotation at the manufacturer's recommended speed and torque until they fractured. The number of cycles to failure (NCF) was recorded for each instrument to measure cyclic fatigue resistance. In addition, surface morphology changes resulting from cyclic fatigue were examined by conducting fragment analysis using SEM for each file. This analysis allowed for a closer inspection of the surface alterations caused by cyclic fatigue. Results: The results of the study indicated that group B (ProTaper Gold) exhibited a higher number of cycles before failure compared to the other two groups, indicating a lower incidence of fracture in the severe 90° curvature. SEM examination of the fractured surfaces of the tested files in group B revealed the presence of smooth areas along their borders, which were associated with nucleation and slow fatigue crack propagation. In contrast, group B demonstrated superior cyclic fatigue resistance compared to both groups A and C. Therefore, group B (ProTaper Gold) exhibited the least amount of cyclic fatigue among the three groups. Conclusion: The study conducted in an artificial canal demonstrated that the files in each group fractured at different average cycle counts. Group B (ProTaper Gold) exhibited superior cyclic fatigue resistance compared to the other file systems. Clinical significance: The research provides valuable insights into the performance and durability of these rotary files in preparing curved root canals. Clinicians can utilize this information to make informed decisions regarding file selection and usage protocols, ultimately improving patient outcomes in endodontic treatments.

CYCLIC fatigue; FATIGUE limit; FATIGUE cracks; SCANNING electron microscopy; SURFACE morphology

World Journal of Dentistry, 2024, Vol 15, Issue 7, p579

0976-6006

Academic Journal

10.5005/jp-journals-10015-2463