Changes in bovine enamel after treatment with a 30% hydrogen peroxide bleaching agent

The purpose of this study was to investigate the effect of long-period exposure of 30% hydrogen peroxide on bovine enamel. Polished labial surfaces were scanned using an atomic force microscope after bleaching for 120 hours. Compositional change and microhardness of the enamels were evaluated using a Fourier transform Raman spectrophotometer and Vickers hardness tester. The same tests were performed on enamels stored in distilled water. In the FT-Raman spectra of both the unbleached and bleached enamels, peaks remained unchanged except for negligible decrease in intensity. As for microhardness, it significantly decreased after bleaching when compared to the original value (p<0.0001). However, the microhardness values of enamels stored in the bleaching agent and distilled water did not show any statistical difference. Based on the results of this study, the use of 30% hydrogen peroxide solution for dental bleaching should be safe due to its negligible effects on tooth morphology and structure.