Effect of bleaching treatment over enamel microhardness from bulimic patients

Frequently, bulimic patients seek to improve their esthetic appearance by dental bleaching. Objective: considering that both bulimia and dental bleaching can alter dental structure, the aim of this study was to assess the effect of associating two demineralizing processes (bleaching and bulimia) on the microhardness of tooth enamel. Methods: 30 fragments of included human third molars were used, and divided into 3 groups: G1 – simulated bulimia (0.01 HCl, 2x/day, 21 days); G2 – simulated bulimia and bleaching treatment (10% carbamide peroxide, 2h/day, 14 days); G3 - bleaching treatment. During the intervals, all fragments were kept in artificial saliva. Knoop microhardness tests (KHN, 25g, 5s) were performed before, during (14 days) and after treatments. ANOVA and Tukeyxs test were used to compare treatments (capital letters) and time (small letters). Results: as mean ± SD, Initial: G1=385.4±128.6Aa, G2=337.2±93.2Aa and G3=345.7±45.7Aa; 14 days: G1=149.1±93.9Bb; G2=132.5± 40.5Bb; G3=264.3±90.8Aab; final G1=117.6±54.6Bb; G2=142.1±30.2Bb; G3=242.2±92.0Ab. Conclusion: bleaching treatment does not potentate mineral loss in the tooth enamel of bulimic patients, considering that it had already suffered significant mineral loss.