Do different bleaching protocols affect the enamel microhardness

摘要: Objective: Tooth bleaching tends to increase enamel roughness and porosity, in addition reducing surface microhardness. The aim of this vitro study was evaluate the effects treatments using different hydrogen peroxide (HP) concentrations, with without light activation on bovine Materials Methods: buccal surfaces sixty incisors were flattened polished specimens divided into six groups: G1 : c0 ontrol, exposed artificial saliva; G2: 35% HP applied two sessions (45' each); G3: (3 × 15' G4: one session 7'30) plus hybrid (HL); G5: 25% HL; G6: 15% HL. After treatment, stored saliva. microhardness (Knoop) measured at baseline, 24 h 7 days after bleaching. data analyzed ANOVA test, followed by Tukey-Krummer test ( P Results: All procedures lead a decrease when compared control group h. lowest change found treated However, HL induced highest remineralization, returned normal levels for all bleached specimens. Conclusion: Therefore, it can be concluded that protocols caused slight alteration. remineralization process minimized these effects.