Comparação da análise de DSC e das forças liberadas na desativação de fios ortodônticos de NiTi termoativados 0,016"

Abstract

The structural phase transformation of five brands of nickel-titanium (NiTi) heat activated wires was evaluated through Differential Scanning Calorimetry (DSC). We also investigated the forces released in the deactivation in three-point bending test. The orthodontic wires of NiTi with a cross section of 0,016": Flexy Thermal Sentalloy® (GAC International), NITINOL Termo Ativado 35ºC (Eurodonto), Thermo- Plus® (Morelli), FlexyNiTi® Flexy Thermal 35ºC (Orthometric) e Damon® CuNiTi 35ºC (ORMCO Corp.) were used for the tests. Five arch of each wire in the as received condition, were cut into five segments of 3mm length for DSC testing (-20/ 80 ° C to 10 ° C / min). Six arch of each wire were cut into six segments of 30mm length for bend test in the universal testing machine, according to ISO 15.841:2006. Data were analyzed using ANOVA followed by post-hoc Tukey test and performed a Pearson correlation test between the results found in the DSC tests and analysis of three points (p <0,05). The results obtained in the DSC analysis and the analysis of three-point present statistical differences. Except for the results obtained at 3mm of deactivation in three-point bending test, all wires showed statistically similar results and presented a correlation between the phases Mf, Af and Exothermic Peak in relation to the force variation in the test of three points.