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Purpose: To evaluate the effect of three different fluoride treatments on the surface microhardness and morphology of human enamel exposed to two different bleaching agents.

Materials and Methods: Twenty-three extracted human third molars were sectioned to obtain 90 enamel fragments, mounted on acrylic resin supports, polished and randomly divided into 9 groups (n= 10). The specimens were exposed to a combination of two bleaching agents (22% carbamide peroxide [CP] and 38% hydrogen peroxide [HP]) and three fluoride treatments (0.05% NaF daily, 0.2% NaF weekly and 5% NaF final topical fluoridation). The positive control group specimens were not exposed to bleaching agents or fluoride treatments. The negative control group specimens were exposed to the bleaching agents but none of the fluoride treatments. All specimens were stored in artificial saliva during the entire experiment, and enamel …