LAUSR

Introduction: The aim of this study was to evaluate the cyclic and torsional fatigue resistance of the following reciprocating single‐file systems: ProDesign R 25.06 (Easy Equipamentos Odontológicos, Belo Horizonte, Brazil), Reciproc R25 (VDW GmbH, Munich, Germany), and Unicone L25 (Medin SA, Nové Město in Moravě, Czech Republic). Methods: Sixty instruments of the ProDesign R, Reciproc R25, and Unicone L25 systems (n = 20) were used. Cyclic fatigue resistance was tested measuring the time to failure in an artificial stainless steel canal with a 60° angle and a 5‐mm radius of curvature (n = 10). Torque and angle of rotation at failure of new instruments (n = 10) in the 3 mm from the tip portion were measured during torsional testing according to ISO 3630–1. The fractured surface of each fragment was examined by scanning electron microscopy. Data were analyzed using 1‐way analysis of variance and Tukey tests, and the level of significance was set at 5%. Results: The cyclic fatigue resistance values of ProDesign R 25.06 were significantly higher than the other groups (P < .05). Reciproc R25 showed higher fatigue resistance than Unicone L25 (P < .05). In relation to the torsional test, the ProDesign R 25.06 and Unicone L25 systems showed higher angular rotation until fracture than Reciproc R25 (P < .05). However, Reciproc R25 and Unicone L25 showed higher torque load than ProDesign R 25.06 (P < .05). Scanning electron microscopic analysis showed similar and typical features of cyclic and torsional failure for all instruments tested. Conclusions: ProDesign R presented the highest cyclic fatigue resistance and angular rotation to failure compared with Reciproc and Unicone. However, Reciproc showed higher torsional strength to failure. HighlightsNew reciprocating systems were introduced using different designs and nickel‐titanium (NiTi) alloys.There are no studies regarding the cyclic and torsional fatigue resistance of ProDesign R.There is no report of the torsional properties of Unicone.Different cross‐sectional designs and the types of NiTi alloy affected the cyclic and torsional fatigue resistance of the reciprocating system.ProDesign R had the highest cyclic fatigue resistance values and angular rotation to fracture.Reciproc showed higher torsional strength to failure.