ABSTRACT
Background: In clinical practice, rotary nickel-titanium (NiTi) has been used several times for a variety of factors. Therefore, patient cross-contamination must be prevented through autoclave sterilization. The impacts of further heat retreatment encouraged during autoclaving methods can impair rotary NiTi mechanical properties since thermo-mechanical processing has a significant influence on its qualities. Objective: This research aims to investigate cycle fatigue resistances of One Curve (OC), M3-L Platinum (M3LP), and Hyflex EDM (HEDM) rotary NiTi, as well as the effects of several autoclave sterilizations. Methods: Six OC, six M3LP, and six HEDM were included in this research. The files were examined in a custom-made stainless steel canal simulator. Each brand of NiTi files was categorized into three distinct subgroups: group 1, the instruments as received—this group was used to determine the baseline mean cycles for fracture; group 2, instruments that were subjected to 25%, 50%, and 75% of the mean cycles to failure; and group 3, instruments that were subjected to the same test as group 2 but without any sterilization. After that, the number of failures, referred to as NCF, was measured. A one-way ANOVA and post hoc Tukey testing were used in order to conduct the statistical analysis. Result: HEDM demonstrated significantly greater NCF in group 2 (6840) compared to group 1 and group 3 or other brands (p <0.05). In general, all tested files (regardless of baseline, with or without sterilization) showed higher cyclic fatigue resistances in the HEDM group (p<0.05) which NCF was the highest, followed by M3LP then OC. Conclusion: In the same autoclave treatment, HEDM had the highest NCF. HEDM exhibited the highest NCF among One Curve and M3-L Platinum during the same autoclave treatment. It appears that autoclaving affects the cyclic fatigue resistance of heat-treated NiTi instruments.
