Efficacy of in-office bleaching techniques combined with the application of a casein phosphopeptide-amorphous calcium phosphate paste at different moments and its influence on enamel surface properties

OBJECTIVES: The aim of this in vitro study was to investigate the efficacy of in-office bleaching technique combined with the application of a casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste (MI Paste–MI) at different moments and its influence on enamel surface properties. METHODS: Eighty bovine dental crowns were randomly allocated into eight groups (n = 10), and bleached with either 35% hydrogen peroxide (HP) or 37% carbamide peroxide (CP). Four different protocols of application of MI were considered: without MI, MI applied before bleaching, MI applied after bleaching, and MI applied both before and after bleaching. Bleaching effectiveness was measured by the VITA EasyShade spectrophotometer utilizing the CIEL*a*b* system (ΔE, ΔL*, Δa*, and Δb*). Color readings were measured at baseline, 7, 14, and 21 days. Hardness and roughness were measured at baseline (T0) and immediately after bleaching (T14). Data were subjected to the two-way ANOVA for repeated measurements and Tukey's test at 5%. RESULTS: HP groups achieved the greatest color change. The application of a CPP-ACP paste did not reduce the efficacy of bleaching peroxides. Samples bleached with CP showed decreased hardness at T14. Samples bleached with HP that received the application of MI before and before/after bleaching did not present hardness decrease at T14. Samples bleached with peroxides only and received MI after bleaching showed increased roughness at T14. CONCLUSIONS: The use of CPP-ACP was able to prevent negative changes in roughness and hardness of bovine enamel when associated to hydrogen peroxide, and might be applied before/after the bleaching protocol. Microsc. Res. Tech. 75:1019–1025, 2012. © 2012 Wiley Periodicals, Inc.