An analysis of cyclic fatigue resistance of reciprocating instruments in different canal curvatures after immersion in sodium hypochlorite and autoclaving: An in vitro study.

Aim: The aim of this study is to assess the effect of sodium hypochlorite and sterilization on the cyclic fatigue resistance of two reciprocating nickel‑titanium files using a rotary and a reciprocating motor. Materials and Methods: Totally, 160 Reciproc and Wave One files were tested. The eighty files of the same brand were assigned into four groups (n = 20). These four groups were further divided into two subgroups, 1a and 1b, 2a and 2b, 3a and 3b, 4a and 4b consisting of ten files in each group. 2.5% NaOCl for 5 min, 2.5% NaOCl for 5 min + 1 cycle of autoclave sterilization, 2.5% NaOCl for 5 min + 5 cycles of autoclave sterilization, no sterilization (control). Groups 1a, 2a, 3a, and 4a were subjected to 30° and Groups 1b, 2b, 3b, and 4b were subjected to 60° canal curvature. Results: Intergroup comparison reveals that there is an increase in cyclic fatigue resistance from the first cycle to the fifth cycle of autoclave which is statistically significant. Conclusion: Reciproc and Wave One showed reduced cyclic fatigue resistance on immersion in NaOCl for 5 min. Multiple autoclaving cycles significantly increased the cyclic fatigue resistance of Reciproc file system in both the curvatures. There was a decrease in cyclic fatigue resistance for Wave One after multiple autoclaving at 60° curvature which was statistically significant. [ABSTRACT FROM AUTHOR]