Torsional and bending resistance of WaveOne Gold, Reciproc and Twisted File Adaptive instruments

Aim To compare the torsional and bending resistance of WaveOne Gold (Dentsply Tulsa Dental Specialties, Tulsa, OK, USA), Reciproc (VDW, Munich, Germany) and Twisted File Adaptive (Axis/SybronEndo, Orange, CA, USA) instruments. Methodology Torsional strength of WaveOne Gold primary size 25,.07 taper, Reciproc size 25, .08 taper and Twisted File Adaptive M-L1 size 25, .08 taper was measured by fastening the apical 3 mm of the instrument firmly and applying a constant rotation at 2 rpm to the instrument using a torsiometer. The fractured instruments were examined using a scanning electron microscope (SEM). The bending resistance of the instruments was measured using the cantilever bending test. The data were statistically analysed using one-way analysis of variance (ANOVA) and Tukey post hoc tests. The statistical significance level was set at P < 0.05. Results WaveOne Gold had a significantly higher torsional resistance than Reciproc and Twisted File Adaptive (P < 0.001). Reciproc had a significantly higher torsional resistance than Twisted File Adaptive (P < 0.001). WaveOne Gold had a significantly lower resistance to bend than Reciproc and Twisted File Adaptive (P < 0.001). There was a significant difference in bending resistance between Reciproc and Twisted File Adaptive instruments (P < 0.001). SEM of the fracture cross-sectional surface displayed the classical features of torsional failure, including fibrous dimple marks near the centre of rotation and circular abrasion marks. Conclusions WaveOne Gold exhibited higher resistance to torsional stress and flexibility compared with Reciproc and Twisted File Adaptive instruments. Torsional resistance and flexibility properties of the instruments could be affected by the alloy from which the instrument is manufactured and different cross-sectional design.