Effect of simulated clinical use and sterilization on the cyclic fatigue resistance of nickel titanium files.

Abstract

Assess the effect of simulated clinical use and sterilization on the cyclic fatigue resistance of Race Evo and Tia Tornado Blue nickel titanium (NiTi) files. For this study, a total of sixty-four NiTi files were selected, with thirty-two files each from two different manufacturers. Files from each manufacturer were subdivided into four subgroups (n=8) based on the test parameters. The control groups included files that were neither used nor sterilized. Files from the test groups were used to prepare the root canals of extracted mandibular premolars and then sterilized. This procedure was repeated once, twice, or thrice, depending on the test group. All files were then subjected to a cyclic fatigue test. Data was statistically analyzed using the Kruskal-Wallis and Mann-Whitney U tests. No significant difference was observed in the number of cycles to failure (NCF) among the subgroups for both types of files (P=0.869 for Tia Tornado Blue, P=0.626 for Race Evo). Tia Tornado Blue files displayed significantly higher NCF values in the control (P=0.021), once (P=0.027), and thrice (P=0.031) usage groups when compared to Race Evo files. Repeated clinical use and sterilization for up to three cycles did not affect the cyclic fatigue resistance of Race Evo and Tia Tornado Blue files.