Protective Effects of CPP-ACP and Calcium Phosphate on Dental Enamel Bleached With 16% Carbamide Peroxide

Objectives: The aim of the present study was to analyze the protective effects of CPP-ACP and nanostructured calcium phosphate on the surface hardness and roughness of tooth enamel.
Methods: This study was conducted using 25 healthy human third molars sectioned mesiodistally to make 50 half-crowns, which were randomly divided into five treatment groups for each test performed: CP = 16% carbamide peroxide; CPMI = 16% carbamide peroxide and MI Paste™; CPNP = 16% carbamide and Desensibilize NanoP^®; MI = MI Paste™; and NP = Desensibilize NanoP^®. The whitening procedure was performed over 21 days, and hardness and roughness readings were obtained at baseline and at 7, 14, 21 and 28 days. Throughout the experiment, the samples were brushed using a brushing machine with 200 g of force and 250 cycles/day. Remineralizing products were applied to the dental enamel surface, according to the manufacturers’ directions. Two-way ANOVA for a complete factorial design and the Games-Howell Test (α=5%) were used to analyze the results from each group.
Results: The results showed that the roughness test was not significantly different among the groups, but the initial and final hardness values were different for the CP, MI and CPMI groups (p<0.05).
Conclusions: The 16% carbamide peroxide whitening agent did not affect roughness, but the hardness of the dental enamel changed. Calcium phosphate, with or without the whitening agent, improved enamel hardness. CPP-ACP combined with the 16% carbamide peroxide whitening agent did not affect hardness or roughness.