Influence of Operator's Experience on Mechanical Properties of Nickel-Titanium Instruments After Usage

This study aimed to evaluate the influence of the operator's experience level on the cyclic fatigue and torsional resistance of OneCurve (OC) and OneRECI (OR) instruments. Four inexperienced clinicians and four endodontists shaped endo-training blocks. Instruments were then subjected to cyclic fatigue and torsional tests under body temperature (37°C) condition (n = 10). The results were analysed using two-way ANOVA test and Tukey HSD post hoc comparison at a significance level of 95%. OR used by inexperienced operators had a longer time to fracture compared to other groups (p < 0.05). Used OC instruments showed longer time to fracture than unused ones (p < 0.05). No significant differences were found in ultimate strength and toughness regardless of experience level and instrument type (p > 0.05). Within the limitation of the present study, operators' experience may have different effects on the mechanical properties of the files based on the instruments' kinematics.