Abstract
Nickel-titanium (NiTi) rotary endodontic instruments have significantly improved root canal treat-ment due to their superior flexibility and fracture resistance. However, their effectiveness can be compromised in curved root canals, where they are susceptible to cyclic fatigue, leading to instru-ment breakage and potential complications. This study aimed to evaluate the cyclic fatigue resistance of three different NiTi rotary endodontic instruments using a static testing apparatus. Thirty-six files, twelve each of Orodeka Plex V, Super Flexi Files Gold, and Fury L60, were subjected to a 45-degree curvature with a 5-mm radius. Each file was rotated at 300 RPM with a 2 N/cm torque until fracture. The number of cycles to fracture (NCF) was recorded for each instrument. The significance level was set at p ≤0.05. Statistical analysis revealed significant differences in cyclic fatigue resistance among the three groups, with Fury L60 demonstrating the highest resistance, followed by Super Flexi Files Gold and Orodeka Plex V. However, no significant differences were observed in fragment fracture length among the groups. In conclusion, Fury L60 exhibited the highest resistance to cyclic fatigue among the tested NiTi instruments. All instruments fractured at the midpoint of the curvature, with consistent fragment lengths.