Effect of fluoride theraphies on the surface of bleached enamel

Objectives: This in vitro study evaluated the effect of different fluoride therapies on the surface roughness of human dental enamel exposed to different bleaching agents. Methods: Sixty-six specimens obtained from a total of thirty-three 3rd molars that were centrally cut, mounted on acrylic supports, polished and submitted to baseline surface roughness readings (RaB). Next, the specimens were distributed into 11 groups and exposed to one of the bleaching agents (16% carbamide peroxide (CP) or 35% hydrogen peroxide (HP)), and one of the fluoride therapies (0.05% NaF (DF); 0.2% NaF (WF); 2% final topical fluoride (FTF); 2% initial and final topical fluoride (IFTF)). The positive control group consisted of specimens that were neither exposed to bleaching agents nor fluoride therapies. Negative control group consisted of specimens exposed to the bleaching agents and to none of the fluoride therapies. After being stored in artificial saliva for seven days, final surface roughness readings (RaF) were taken. Percentage differences between RaB and RaF were analyzed by ANOVA and Tukey's HSD tests at a p-value of 0.05. Results: The bleaching agents CP and HP increased the surface roughness compared with the control group; FTF and IFTF reduced the surface roughness of enamel exposed to CP and HP; DF and WF did not reduce the surface roughness of enamel exposed to CP and HP. Conclusions: Both bleaching agents tested increased the surface roughness of dental enamel, and both topical fluoride therapies were effective in reducing the increase in enamel surface roughness after bleaching.