Morphological Alterations of Enamel After Bleaching With or Without Calcium

Objectives: The purpose of this study was to assess the effect 7,5% and 9,5% hydrogen peroxide (HP) bleaching agent with or without addition and different treatments of remineralization on enamel microhardness and induced structural and quantitative changes.The purpose of this study was to assess the effect 7,5% and 9,5% hydrogen peroxide (HP) bleaching agent with or without addition and different treatments of remineralization on enamel microhardness and induced structural and quantitative changes.
Methods: Enamel blocks (3x3mm) obtained from thirty bovine incisors were divided in four groups (n=10): G1 9,5% hydrogen peroxide bleaching; G2 9,5% hydrogen peroxide bleaching with Ca; G3 7,5% hydrogen peroxide bleaching; G4 7,5% hydrogen peroxide bleaching with Ca. Enamel slabs received the bleaching agents 30min (PH9,5%)- e 45min (PH7,5%) for day and remained in artificial saliva solution until complete 24 h/day, during a total period of 14 days. Control group was the same samples before the bleaching treatment. Microhardness tests (HKN) were performed before treatment applications, after bleaching and post remineralization. The Fourier transform infrared spectroscopic (FTIR) technique was used to analyze band frequency phosphate and carbonate before and after bleaching treatment and post remineralization.
Results: Results obtained were statistically analyzed by Anova and Tukey’s test, p<0,05. The results showed significant differences in microhardness and FTIR values among bleaching agents with calcium, at 14 days of treatment and a significant increase in microhardness for different agents after remineralization treatment.
Conclusions: Bleaching agents containing calcium may result less mineral loss, however after remineralization all groups showed increase microhardness and phosphate/carbonate bands.