Comparison of cyclic fatigue of a reciprocating file system at different angles of rotation

Abstract

Aim: The purpose of this in vitro study is to compare the cyclic fatigue resistance of Reciproc Nickel-Titanium (Ni-Ti) rotary files (VDW GmbH, Munich, Germany) while operating root canals using in three different reciprocal angles. Methodology: Forty-five Reciproc R25 root canal files were tested using artificial canals with a 60° angle of curvature, 5 mm curvature radius, and 1.5 mm diameter carved into a stainless steel block. The Ni-Ti files were checked with a stereomicroscope and then randomly separated into three groups. Group 1 consisted of reciprocal angles CCW 150°— CW 30°, Group 2 consisted of CCW 180°—CW 60°, and Group 3 consisted of CCW 210°— CW 90°. The duration of the cyclic fatigue being measured, elapsed time until a file fractured was determined with a chronometer. The lengths of the fractured pieces were measured with a digital caliper. After the cyclic fatigue test, two samples from each group were examined with a Scanning Electron Microscope (SEM) to determine the signs of cyclic fatigue. Results: One-way analysis of variance (ANOVA) was applied to the normally distributed groups (p