Torsional behavior of WaveOne Gold endodontic file with the dedicated motor of the original WaveOne file

This study compares the safety limits and torsional resistances ofWaveOne Gold (WOG) and WaveOne (WO) endodontic files while using the original motor. The safety limits for reciprocating angles were tested by measuring the torsional limit before plastic deformation (TLP) after repetitive torsional loading at gradually increasing load, and after single continuous rotation. Statistical analysis was performed by independent t-test at 95% confidence level. The tested specimens were observed under a scanning electronmicroscope (SEM). Regardless of the testmode, the distortion angle at the TLP was higher forWOG thanWO (p < 0.05), and allwere greater than the 150-degree rotation of the original motor. The mean values of the distortion angle and torque from the single continuous rotation loading were significantly lower than those with repetitive loading movements. Comparing the two systems under SEM, WO showed a catastrophic change in comparison withWOG. Evaluation of the lateral aspects showed longitudinal micro-cracks after 270-degree repetitive movements. After 150-degree repetitive movements, no distorted machining grooves were found in either group, butWO showed evidence of longitudinal micro-cracks. Under the conditions of this study, the torsional loading from the pre-set mode of the dedicated motor forWO was safe forWOG as well.