Avaliação das cargas de adesão e das superfícies do esmalte dentário após a remoção de bráquetes ortodônticos cerâmicos e metálicos: uma visão por microscopia eletrônica de varredura

Abstract

This study aimed at evaluating, in vitro, the shear bond strength shown by three different brands of polycrystalline ceramic orthodontic brackets and a brand of metallic orthodontic bracket, all with mechanical retention, by verifying the adhesive remnant index after trials, and to analyze, by means of scanning electronic microscopy, the superficial enamel topographies after debonding, detecting the release of mineral particles of enamel after bracket removal. Sixty recently extracted mandibular bovine incisors were used in this study. Polycrystalline ceramic brackets (Allure®, InVu®, and Clarity®), and metallic brackets (Geneus®) were bonded with Transbond XT®. For the results concerning the shear bond strength the KruskalWallis test was applied with a significance level of 5%. The Mann Whitney test was performed to compare the different types of brackets by pair, in relation to the adhesive remnant. For the analysis of the results concerning the chemical composition of the enamel the Brown-Forsythe test was applied with a significance level of 5%. Comparisons between the groups were analyzed using the GamesHowell Post Hoc test. No statistically significant differences were observed in relation to shear loads during bracket debonding. In relation to ARI, when the pairs are compared, it was possible to observe statistically significant differences between Clarity and InVu brackets (p = 0,002), Allure and InVu (p = 0.006), and Clarity and Geneus (p = 0.0022). The prevalence of score “4” was confirmed with a percentile of 40.4%. In relation to the superficial enamel topography, the Geneus® bracket was the only one which did not show loss of superficial tissue. Clarity® brackets was the most affected in relation to superficial topography and to the release of mineral particles of enamel (Ca ions). InVu® and Clarity® brackets showed cohesive fractures in 33.3% of their samples and the Allure® in 50%, the latter being the one that presented most fractures during removal.