Impact of the reuse of reciprocating instruments on cyclic fatigue resistance: WaveOne Gold and R-Motion

This study aimed to evaluate the cyclic fatigue resistance of WaveOne Gold (WOG) and R-Motion (RM) nickel-titanium instruments after multiple simulated clinical uses. A total of 48 instruments (24 WOG and 24 RM) were tested. For each instrument system, files were divided into four subgroups (n=6 per subgroup) based on the number of prior simulated clinical uses: WOG0 and RM0 (new, no prior use), WOG1 and RM1 (single prior use), WOG2 and RM2 (two prior uses), and WOG3 and RM3 (three prior uses). Instrumentation was performed in 3D-printed resin teeths designed to simulate the mesial root canals of mandibular first molars. Subsequently, all instruments were subjected to a dynamic cyclic fatigue test in a stainless-steel artificial canal until fracture occurred. The number of cycles to fracture (NCF) was recorded. The groups had a normal distribution and were analyzed using the parametric ANOVA test, considering a 95% confidence interval, where the One-Way ANOVA, Bonferroni, Tukey, and Scheffe’ tests were used. The time to fracture of the RM was higher when compared to the WOG (p 0.05). There was no significant difference between the length of the fractured instruments. Although both instruments showed good resistance to cyclic fatigue after 3 uses, the RM had better cycle fatigue resistance than the WOG.