In vitro analysis of the degradation of the orthodontics rubber bands tensile strength in function of the quantity of activation / Análise in vitro, da degradação de forças dos anéis elásticos ortodônticos em função da quantidade de ativação.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The objective of this research is to analyze the quantity of degradation of the orthodontics rubber bands tensile strength in relation to different intensities of tivation twice, three times and four times their diameter in a relaxed state; the quantity and the level of degradation of the rubber bands tensile strength in relation to different commercial brands studied; and to assess the rubber bands dimensional changes from several brands between the beginning and the end of this experiment. Elastic bands from 3M Unitek, American Orthodontics, GAC, Masel, Morelli and Uniden brands were tested in such dimensions: 1/8-inch, 3/16-inch, 1/4-inch and 5/16-inch. The rubber bands were divided in four groups according to their dimensions. Each subgroup consisted of 10 samples from each commercial brand. These elastics were activated and attached to acrylic plaques that were immersed in distillated water at 37C for a period of 5 days. After that, they were removed to measure their tensile strength by a dynamometer in periods of 1, 6, 24, 48 and 120 hours. Besides, the elastics had their diameters measured by a digital paquimeter in the beginning as well at the end of the experiment to verify the dimensional variations and the permanent deformation. The data was submitted to analysis and statistics using the analysis of variance and the Tukey test. The results presented great diversity. Trough those results, it was observed that there was an expressive variation related to the initial tensile strength as well as in terms of activation protocols. The protocols with more quantity of activation presented more tensile strength intensity if compared to the less ones. In relation to the strength degradation, it has observed a higher degradation in the protocols with more quantity of activation in contrast to the less ones, many times not demonstrating statistical significance. Among the brands, there were variations in results in all groups, however, the elastics that suffered more degradation were the 3M Unitek, and the ones with less degradation were the Uniden. All the rubber bands suffered permanent deformation, although this deformation was more intense in the protocols with more quantity of activation. The elastics that suffered less quantity of dimensional alterations were the Uniden and GAC brands.

ASSUNTO(S)

dental materials elastomers materiais dentÁrios elastÔmeros ortodontia

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