Effect of autoclave sterilization on cyclic fatigue of EdgeTaper platinum and ProTaper gold nickel–titanium rotary instruments: An in vitro study

Abstract

Introduction: The heat during autoclave process affects the fracture resistance of the nickel–titanium rotary file and might exert some effect on its mechanical properties. This study aimed to evaluate the effect of autoclave sterilization on cyclic fatigue of EdgeTaper Platinum® and ProTaper Gold®. Materials and Methods: Forty new files from EdgeTaper Platinum® and ProTaper Gold® rotary files with a #25 tip size were used in this study. Each system was subdivided into four groups according to the sterilization cycle; Group 1: No sterilization, Group 2: Two cycles of sterilization, Group 3: Five cycles, and Group 4: Ten cycles. Cyclic fatigue was evaluated using an artificial stainless steel canal with 60° of curvature and 5 mm radius of curvature at 37°C. The number of cycles to failure (NCF) was calculated and compared using Kruskal–Wallis test and Mann–Whitney U-test. The surface of the fractured file was evaluated with scanning electron microscopy. Results: There were significant differences within the two file brand subgroups regarding the NCF (P > 0.05). ProTaper Gold® also revealed no significant differences in NCF (P > 0.05) related to the sterilization conditions. In addition, EdgeTaper Platinum® showed significantly higher cyclic fatigue resistance than ProTaper Gold® in all groups of this experiment (P < 0.05). The fractured plane showed typical features of cyclic fatigue failure for all instruments. Conclusion: Autoclave sterilization did not affect cyclic fatigue resistance of both EdgeTaper Platinum® and ProTaper Gold® in all groups of the experiment. When compare in each group of this experiment, EdgeTaper Platinum® exhibited higher cyclic fatigue resistance than ProTaper Gold®.