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RESEARCH PRODUCT

Effects of in-office bleaching on human enamel and dentin. Morphological and mineral changes

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Abstract Background The effects of HP-based products upon dental enamel and dentin are inconclusive. Aim To evaluate changes in micromorphology and composition of calcium (Ca) and phosphate (P) in enamel and dentin after the application of 37.5% hydrogen peroxide (HP) and 35% carbamide peroxide (CP) Methods Crowns of 20 human teeth were divided in two halves. One half was used as control specimen and the other as experimental specimen. The control specimens were kept in artificial saliva, and the experimental specimens were divided into four groups (n = 5 each): group 1 (enamel HP for 45 min); group 2 (dentin HP for 45 min); group 3 (enamel CP for 90 min); and group 4 (dentin CP for 90 min). The morphological changes were evaluated using confocal laser scanning microscopy (CLSM), while the changes in the composition of Ca and P were assessed using environmental scanning electron microscopy combined with a microanalysis system (ESEM + EDX). The results within each group and between groups were compared using the Wilcoxon test and Mann–Whitney U-test, respectively (p  Results Similar morphological changes in the enamel and no changes in dentin were assessed with both products. Ca and P decreased in enamel and dentin, without significant differences between them or with respect to their control specimens (p > 0.05). Conclusions When bleaching products with a neutral pH are used in clinical practice, both, the concentration and the application time should be taken into account in order to avoid possible structural and mineral changes in enamel and dentin.