The possibility to minimize enamel changes after tooth whitening would be a benefit to the patient. The aim of this study is to evaluate in vitro the addition of calcium glycerophosphate (CaGP) associated with 0.05% sodium fluoride and 35% hydrogen peroxide on the mechanical properties of enamel. Bovine enamel blocks (4 mm x 4 mm, n = 60) will be selected by initial surface hardness (SHI) and divided into six groups (n = 10) according to bleaching gels: 1)35% hydrogen peroxide (PH); 2) PH + 0.1% NaF (PH/F); 3) PH + 0.25% CaGP (PH/CaGP); 4) PH + 0.1% NaF + 0.25% CaGP (PH/F/CaGP) ; 5) HP Blue 35% (FGM - Produtos Odontológicos: HP Blue) and 6) Whiteness HP 35% (FGM - Produtos Odontológicos: HP). The gels will be applied only once, during 3 sessions of 40 minutes/session, every 7 days, totaling 21 days. Between treatment sessions the blocks will remain in artificial saliva, which will be changed daily. Then the final surface hardness (SHF) will be determined to calculate the percentage of surface hardness loss (%SH) and integrated subsurface hardness loss (KHN). For physicochemical characterization of the bleaching gels, they will be evaluated for polydispersity index (Pdl) and zeta potential. The data will be submitted to ANOVA followed by the Student-Newman-Keuls test (p < 0.001) if they present normal and homogeneous distribution. Otherwise, Kruskal-Wallis analysis and the Student-Newman-Keuls test will be used (p < 0.001).
News published in Agência FAPESP Newsletter about the scholarship: