ABSTRACT Aim: Nickel–titanium (NiTi) rotary instruments have become indispensable in contemporary endodontics due to their remarkable flexibility and superior resistance to cyclic fatigue. Sterilization, particularly through autoclaving, is routinely employed to prevent cross-contamination. However, the thermal and mechanical stresses introduced by repeated autoclave cycles may compromise the structural integrity and functional longevity of these instruments. This study aimed to evaluate and compare the impact of repeated autoclave sterilization cycles on the cyclic fatigue resistance of three distinct NiTi rotary file systems: ProTaper Gold, Edge Taper Platinum, and HyFlex electric discharge machining (EDM). Methods: Thirty-six unused NiTi rotary files were allocated into three groups ( n = 12): Group A: ProTaper Gold, Group B: Edge Taper Platinum, and Group C: HyFlex EDM. Each group was subdivided into sterilized and nonsterilized subgroups ( n = 6). Cyclic fatigue resistance was assessed using a stainless-steel artificial custom-made canal, and the number of cycles to fracture (NCF) was recorded for each instrument. Data were analyzed using SPSS v21 software. Paired Student’s t -tests were applied to compare NCF values within each group. Results: Sterilization resulted in a statistically significant increase in cyclic fatigue resistance for Edge Taper Platinum ( P = 0.003) and ProTaper Gold ( P = 0.05). Conversely, decreased cyclic fatigue resistance of HyFlex EDM was noted poststerilization ( P = 0.02). Conclusion: Autoclave sterilization improved cyclic fatigue resistance in ProTaper Gold and Edge Taper Platinum but decreased in HyFlex EDM.
Maheswari et al. (2026) studied this question.