Wear and surface roughness of bovine enamel submitted to bleaching.

The present study evaluated surface roughness and wear of bovine enamel following three different bleaching techniques and simulated brushing. Initial surface roughness (Ra) was evaluated and teeth were randomly divided into 4 groups (n = 10): Group 1, control; Group 2, 35% hydrogen peroxide (HP) activated by a hybrid light; Group 3, 35% HP activated by a halogen light; and Group 4, 16% carbamide peroxide. After bleaching, surface roughness was measured and teeth were subjected to 100,000 cycles of simulated brushing. After brushing, the final roughness and wear was determined. Data were statistically analyzed by ANOVA and Tukey test (P < 0.05). There were no significant differences among groups comparing initial and postbleaching roughness. After brushing, significant differences were found between the control and experimental groups. Group 4 showed a significant increase in roughness values compared with Group 2. The control group showed significantly less wear than other groups. Bleaching techniques promoted increased roughness and wear of bovine enamel, when submitted to simulated brushing. Tooth enamel after bleaching can present a larger alteration in the amount of roughness due to brushing.