Abstract
The aim of this study was to evaluate the demineralization and hydrogen peroxide (HP) penetration in teeth with incipient lesions submitted to bleaching treatment. For analysis of HP penetration, sound and demineralized enamel/dentin discs were placed in artificial pulp chambers containing acetate buffer solution. After bleaching treatment, this solution was subjected for analysis of optical density by spectrophotometry and the disc surfaces were analyzed with scanning electron microscopy (SEM) and polarized light microscopy (PLM). The remaining discs were subjected for cross-sectional hardness analysis at different depths. Data were analyzed by repeated measures ANOVA and PLSD Fisher test (a=0.05). It was observed that previously demineralized teeth showed greater HP penetration (p<0.05). The bleaching treatment caused changes to a depth of 20 µm in sound enamel and up to 90 µm in demineralized enamel. SEM and PLM images revealed that the bleaching treatment caused superficial changes that were considerably more accentuated in previously demineralized teeth. It may be concluded that the enamel mineralization level influences HP penetration and the bleaching agent contributed to increase the demineralization depth.
Highlights
Tooth bleaching is one of the most popular treatments to achieve esthetic whitening and is considered a conservative, performed and relatively low-cost procedure [1]
The application of repeated-measures ANOVA showed that hydrogen peroxide (HP) penetration, as far as cross-sectional hardness is concerned, was different in groups with sound and demineralized enamel (p
The application of the PLSD Fisher test at 5% significance level showed that the condition of enamel influenced the intensity of the hydrogen peroxide, presenting the highest values in specimens subjected to cariogenic challenge, regardless of bleaching session (Table 1)
Summary
Tooth bleaching is one of the most popular treatments to achieve esthetic whitening and is considered a conservative, performed and relatively low-cost procedure [1]. The patient uses carbamide peroxide gel at low concentrations under the supervision of a dentist. Another alternative for vital tooth bleaching is the in-office technique, characterized by the use of products based on hydrogen peroxide (HP) in concentrations ranging from 20% to 38%. Obtaining fast results with immediate lightening effects through observation is the main marketing appeal that anchors the success of this technique [4]. It is known that whatever the used bleaching agent, the active ingredient that will act in tooth structure is hydrogen peroxide, which should penetrate into the enamel and reach the dentin to produce the desired effect
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