Bending Resistance and Dynamic and Static Cyclic Fatigue Life of Reciproc and WaveOne Large Instruments

Introduction: The aim of the present study was to evaluate the bending resistance and the dynamic and static cyclic fatigue life of Reciproc R40 and WaveOne large in- struments. Methods: A sample of 68 nickel-titanium instruments (25 mm in length) for use under reciprocation movement (Reciproc and WaveOne) from 3 different lots was tested. Reciproc R40 and WaveOne Large files, both of which had a nominal size of 0.40 mm at DO, were selected. The bending resistance was performed in 10 instruments of each system by using a universal testing machine. Dynamic and static models for cyclic fatigue testing were performed by using a custom-made device. For these tests, an artificial canal measuring 1.4 mm in diameter and 19 mm total length was fabricated from a stainless steel tube. Scanning electron microscopy analysis was performed to determine the mode of fracture. Statistical analysis was performed by using parametric methods, 1-way analysis of variance. Post hoc pair-wise comparisons were performed by using Tukey test for multiple comparisons. Results: WaveOne instruments presented significantly higher bending resistance than Reciproc (P <.05). Moreover, Reciproc revealed a significantly longer cyclic fatigue life (P <.05) in both static and dynamic tests (P <.05). Conclusions: Reciproc R40 instruments resisted dynamic and static cyclic fatigue significantly more than WaveOne Large instruments. Furthermore, WaveOne instruments presented significantly less flexibility than Reciproc.