Alterações morfológicas e do conteúdo mineral no esmalte dentário induzidas por tratamentos clareadores.

Abstract

Among the factors that cause smile esthetic alteration are the chromatic modifications, which are mainly treated by bleaching protocols. The aim of this study was to evaluate the morphological and mineral content changes after bleaching treatment with hydrogen peroxide, in intact teeth and with initial caries lesions, involving 3 specific objectives: Specific objective 1: To evaluate the loss of mineral content, expressed by Calcium (Ca) and Phosphorus (P), in dental enamel exposed to bleaching agents based on 35% hydrogen peroxide (HP35%) with and without calcium in the composition, by through micro-CT, SEM, EDS and AFM; Specific Objective 2: To evaluate by using micro-CT the loss of enamel structure, in volume and depth, compared to the bleaching with hydrogen peroxide 37.5% (HP37.5%) and 7.5% (HP7.5%) based gels and also quantifying the loss of Calcium (Ca) and Phosphorus (P), after treatment, by using CI; Specific objective 3: To evaluate the mineral loss in intact (IE) and white spot (WSE) dental enamel after bleaching treatments with HP37.5% and HP7.5%, and subsequently submitted to remineralization with fluoride (F). In conclusion, the micro-CT method was effective to assess loss of enamel structure in volume and depth with high correlation with EDS results. The addition of Ca in the whitening gel composition was not able to prevent the enamel demineralization. The enamel suffered minimal mineral loss located near the surface, regardless of bleaching gel or Ca presence. No change in surface roughness was observed. The bleaching treatment with HP37.5% and HP7.5 caused mineral changes in the tooth enamel; however, the changes were more evident for HP7.5. Ion chromatography proved to be effective for detecting the enamel mineral loss transferred to the whitening gel. The bleaching does not increase mineral loss on WSE. The bleaching protocols using HP7,5% and HP37,5% decreased the VH values for IE substrate, however no influence was verified on Ra and VH of WSE substrate. Severe surface topographic changes were observed only after HP7.5% bleaching for IE substrate. The F application was not able to alter the Ca and P values but it increases the HV of bleached WSE and reduces Ra if HP7.5% were used.