Abstract
The aim of this study was to compare the effect of a 16% carbamide peroxide (CP) gel and a 10% CP gel on mineralized enamel content and morphology. Enamel blocks from bovine incisors were subjected to a 14-day treatment (8 h/day) with 10% or 16% CP gels. Knoop microhardness was evaluated before bleaching and at 1, 7 or 14 days after this treatment (50 g/15 s). Mineral content (energy-dispersive x-ray spectroscopy), surface roughness and topography (atomic force microscopy) were evaluated at the 14-day period. Data were analyzed statistically by two-way ANOVA and Tukey's test (α=0.05). Significant microhardness reduction was observed at the 7 th and 14 th days for 10% CP gel, and for all bleaching times for 16% CP gel (p<0.05). At the 14-day period, a significant decrease in Ca and P content, increase on surface roughness (p<0.05) as well as on picks and valleys distance were observed when both bleaching gels were used. These enamel alterations were more intense for 16% CP gel. It was concluded that both CP-based gels promoted loss of mineral structure from enamel, resulting in a rough and porous surface. However, 16% CP gel caused the most intense adverse effects on enamel.
Highlights
Tooth bleaching is a popular esthetic procedure because of its simple technique, clinical efficacy and non-invasive nature, requiring no sound dental structure removal
A number of studies demonstrated that bleaching gels with high concentrations of hydrogen peroxide (HP), such as those used for in-office tooth bleaching, could promote pulp cell damage [1]
A recent study demonstrated that it is possible to speed up the whitening effect of this technique by increasing carbamide peroxide (CP) concentration [15]
Summary
Tooth bleaching is a popular esthetic procedure because of its simple technique, clinical efficacy and non-invasive nature, requiring no sound dental structure removal. A number of studies demonstrated that bleaching gels with high concentrations of hydrogen peroxide (HP), such as those used for in-office tooth bleaching, could promote pulp cell damage [1] This undesirable adverse effect has been related to the ability of HP to disrupt the mineral structure of enamel [2], which allows HP diffusion to the subjacent dentin and pulp chamber [3]. At-home tooth bleaching technique has been considered as an interesting alternative for bleaching teeth without causing toxic effects to pulp tissue This esthetic procedure is based on patient wearing a custom-made tray filled with low concentrations of carbamide peroxide (CP) or HP gels [4]. Some patients complain about the long treatment time required for this technique
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