Evaluation of cyclic and torsional fatigue resistance of several heat‐treated reciprocating nickel–titanium instruments

Abstract

This study investigated the cyclic fatigue and torsional resistance of Unicone Plus (UCP 25.06), Unicone (UC 25.06), Reciproc Blue (RB 25.08) and Wave One Gold (WOG 25.07) performed at body temperature (35° ± 1°C). Time and number of cycles to fracture (NCF), as well as torque and angular deflection were recorded. Fractured surfaces were evaluated by scanning electron microscopy (SEM). Data were analysed using one‐way ANOVA and Holm–Sidak's tests for multiple comparison. The RB had a significantly higher time to fracture, followed by the WOG and UCP (p < 0.05). Regarding the NCF, there was no significantly difference between RB and WOG (p > 0.05). UC presented highest torque values and the lowest angular deflection (p < 0.05). SEM analysis demonstrated typical failures features in both cyclic and torsional fatigue tests. Overall, UC had the lowest time, NCF and angular deflection at fracture. RB presented the highest time to fracture and angular deflection values.

Cyclic Fatigue of Different Reciprocating Endodontic Instruments Using Matching Artificial Root Canals at Body Temperature In Vitro

“…The present results corroborate current findings showing the superior performance of proprietary heat treatments resulting in blue-coloured instruments [23][24][25]. Heat treatments of NiTi alloys strongly influence the martensitic/austenitic transformation behaviour, favouring a different arrangement of the crystalline structure and a higher percentage of martensitic transformation [26].…”