Avaliação de propriedades termomecânicas de fios de níquel-titânio aplicados na ortodontia.

Abstract

As a result of the diversity of available leagues, with his several manufacture methods, it is important to an ortodontista to know his properties and the connected variables, to plan the treatment and to optimize the clinical results, as well as to preserve the histofisiologia of the periodonto of the patient. In this form, the objective of this study valued and he compared in vitro the properties termomecânicas of threads ortodônticos superelastic daily pay gone of nickel-titanium of two commercial marks. Methods: The commercial marks Morelli® (Group 1) and Orthometric® (Group 2) were used, of which 5 samples were obtained by group, where they were subjected to the tests of DMA (Dynamical Mechanical Analysis) and DSC (Differencial Scanning Calorimetry). The tests of DMA were carried out in the flexing way in three points, and the used parameters were: tax of heating of 5°C/min, in the belt of 30°C to 100°C, 1 Hz frequency and amplitude of 5 μm. For the DSC, the parameters were: tax of heating/cooling of 5°C/min, in the belt of 60 °C to 120 °C, under dynamic atmosphere of air and of nitrogen (for cooling), with flow of gas of the order of 100 ml/min-1, under atmospheric pressure. After the realization of the tests, the obtained data were treated and analysed when is used the software OriginPro 8.5®, when printers are obtained, from the DMA, with the curves of module of elasticity and capacity of deadening (tan δ) in function of the temperature and, from the DSC, printers showing the temperatures of transformation of crystal clear phase of the league. For the analysis of the averages of the modules of elasticity of the samples, the statistical test was employed Test-t de Student, with level of signification of 5 %. Results: The Test-t de Student demonstrated that the difference of the averages of the modules of elasticity of the samples was statistically significant (p < 0,05). The rigidity of both groups increased in function of the increase of the temperature. To 37°C, intrabuccal normal temperature, the Group 1 showed average of superior rigidity up when 2 was compared to the Group, and both showed up in the austenitic phase. Conclusions: With the data of the inquiry, it is possible to end what even the leagues with the same characteristic of superelasticity and, possibly, similar chemical composition, existed difference between the elasticity modules between the commercial marks, under the same study conditions, where the Group 1 presented bigger rigidity when the Group 2, this characteristic that it can favor to a better clinical performance of the first group was compared to the group.