A NiTi rotary instrument manufactured by twisting: morphology and mechanical properties

Victor Talarico Leal Vieira, Carlos Nelson Elias, Hélio Pereira Lopes, Edson Jorge Lima Moreira, Letícia Chaves de Souza

Objectives: The surface morphology of TF® endodontic instruments was studied using stereomicroscopy and scanning electron microscopy (SEM). Mechanical tests were done for flexibility and microhardness. Methods: Four tapers of TF® files was used (0.04; 0.06; 0.08 e 0.10 mm/mm). The stereomicroscopy associated with the AxioVision® program was used to measure the tip angle, the helical angle, the taper and the tip diameter of the instruments. SEM was used to identify surface defects due to machining and finishing. The flexibility and the microhardness were measured with bending and microhardness Vickers tests, respectively. The analysis showed that the manufacturer complied with the values recommended by the ANSI/ADA standard number 28. Results and Conclusions: The SEM results showed many surface defects and a distortion of the instrument helicity. It was observed that the instrument flexibility changes with its taper. The forces to induce the phase transformation by stress on instruments with taper 0.04; 0.06 e 0.08 mm/mm were 100 gf, 150 gf and 250 gf, respectively. The values of microhardness Vickers of the instruments are compatible with rotary instruments manufactured by the machining process.

Keywords: Endodontic instruments. NiTi alloy. R-phase. Materials characterization. Mechanical tests. NiTi manufacturing methods.

How to cite: Vieira VTL, Elias CN, Lopes HP, Moreira EJL, Souza LC. A NiTi rotary instrument manufactured by twisting: morphology and mechanical properties. Dental Press Endod. 2011 apr-june;1(1):21-7.

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