Cyclic and torsional fatigue resistance of four rotary NiTi instruments with similar cross-sectional design and different thermal treatments

Michel Espinosa KLYMUS, Murilo Priori ALCALDE, Rodrigo Ricci VIVAN, Bruno Carvalho de VASCONCELOS, Marcus Vinícius Reis SÓ, Marco Antonio Hungaro DUARTE

Objective: The aim of this study was to evaluate the cyclic and torsional fatigue resistance of Nickel-Titanium rotary instruments with similar cross-sectional design and manufactured by different thermal treatments: Hyflex CM (HCM 25/.06) Vortex Blue (VB 25/.06), Sequence Rotary File (SRF 25/.06) and EdgeSequel (EDF 25/.06) (n=20). Material and Methods: Cyclic fatigue test evaluated the time and number of cycles to failure (NCF) in an artificial stainless steel canal with 60° and 5-mm radius of curvature (n=10). The torsional test (ISO 3630-1) evaluated he maximum torque and distortion angle to failure at 3 mm from the tip (n=10). After the torsional and cyclic fatigue test the instruments were evaluated by scanning electron microscope (SEM). Data were analyzed using one-way ANOVA and Tukey tests, and the level of significance was set at 5%. Results: The HCM presented the longest time and highest NCF to fatigue than all the groups (P<0.05). The SRF presented similar time (P>0.05) and lower NCF (P<0.05) to fatigue than VB. Regarding to the torsional test, HCM presented the lowest torque load and the highest distortion angle of all the groups (P<0.05). No significant difference was found among VB, SRF and EDF regarding the distortion angle (P>0.05). Conclusion: The HCM presented the highest cyclic fatigue resistance and distortion angle to failure. However, the VB showed higher torsional load to failure.

Keywords: Dental Instruments. Endodontics. Nickel. Titanium

How to cite: Klymus ME, Alcalde MP, Vivan RR, Vasconcelos BC, Só MVR, Duarte MAH. Cyclic and torsional fatigue resistance of four rotary NiTi instruments with similar cross-sectional design and different thermal treatments. Dental Press Endod. 2021 Jan-Apr;11(1):63-71.

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