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Evaluation of physicochemical and mechanical properties of NiTi endodontic instruments made with conventional and controlled-memory alloys

Hélio Pereira Lopes, Márcia Valéria Boussada Vieira, Carlos Nelson Elias, Rafael Marques Villagra, Victor Talarico Leal Vieira, Letícia Chaves de Souza

Objective: The aim of this study was to evaluate the semiquantitative composition, flexibility and microhardness of endodontic instruments with conventional and CM NiTi alloy, and to evaluate the influence of continuous rotation and reciprocating movement on the static fatigue life. Methods: Hyflex CM 40/0.04 and RaCe 40/0.04 were submitted to cantilever-bending test, energy dispersive X-ray spectroscopy and Vickers microhardness. Static fatigue tests were performed under continuous rotation; 150° clockwise/30° counterclockwise; 75° clockwise/15° counterclockwise. Results: Hyflex CM is more flexible than RaCe (p < 0.05) whereas no significant difference was observed regarding the microhardness (p > 0.05). RaCe has 55.7%wt Ni and 44.3%wt Ti, while Hyflex CM has 50.81%wt Ni and 42.28%wt Ti. Reciprocation motion showed statistically significant longer fatigue life when compared to the CR for both instruments (p < 0.05). Hyflex CM used with the reciprocating motion with the smallest angle of reciprocation showed statistically significantly longer fatigue life compared with the greater angle (p < 0.05) whereas there was no significant difference for the RaCe instruments (p > 0.05). Hyflex CM showed longer fatigue life than RaCe for all rotation movements (p < 0.05). Conclusion: Hyflex CM had higher flexibility and lower percent of Ni than RaCe. Both instruments had similar microhardness. Hyflex CM had longer fatigue life than RaCe in all rotation movements. Both files had longer fatigue life in reciprocating motion than continuous rotation. Smaller reciprocating angle had better fatigue resistance when compared to the greater angle.

Keywords: Endodontics. Fatigue. Titanium. Nickel. Rotation.

How to cite: Como citar este artigo: Lopes HP, Vieira MVB, Elias CN, Villagra RM, Vieira VTL, Souza LC. Evaluation of physicochemical and mechanical properties of NiTi endodontic instruments made with conventional and controlled-memory alloys. Dental Press Endod. 2016 May-Aug;6(2):28-33. DOI: http://dx.doi.org/10.14436/2358-2545.6.2.028-033.oar

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