Difference of Enamel Microhardness After In Office Bleaching with 38% Hydrogen Peroxide Followed by Application of APF and CPP-ACP

Objectives: To evaluate the difference of enamel microhardness after in office bleaching with 38% hydrogen peroxide followed by the application of APF and CPP-ACP at 2 distinct period of time.
Methods: Forty molars were randomly allocated into 4 groups (n=10) based on sample treatments. All the molars were bleached and applied with remineralization agents. In group I sample were applied APF for 7 days; Group II were applied with APF for 14 days; Group III wereapplied with CPP-ACP for 7 days; Group IV were applied with CPP-ACP for 7 days. Enamel hardness was measured 3 times: before, bleaching, after bleaching, and after the application of mineralized gel. Data obtained was analyzed using ANOVA and Tukey test.
Results: Results showed that there was no significant difference between the application of mineralized gel and enamel hardness (F = 2,830; p = 0,095). There was however, significant difference between measurement time and enamel hardness (F = 13,282; p = 0,000). There was an interaction between mineralized gel and measurement time of enamel hardness (F = 11,513; p = 0,000).
Conclusions: Both of these gels are proven just as effective in terms of increasing enamel hardness after in-office bleaching using 38% hydrogen peroxide. There is a significant difference in enamel hardness measured at different times, which are before bleaching, after bleaching, and after applying mineralized gel (7 days and 14 days respectively).