Assessment of the effects of different remineralizing agents on microhardness of bleached enamel

Abstract

Purpose: The purpose of this study was to evaluate the effect of three remineralizing agents on surface microhardness of enamel bleached by carbamide peroxide based bleaching agent at different time intervals. Materials and Methods: A total of 85 anterior bovine teeth were randomly assigned to 15 groups (n=5) according to the two experimental factors being investigated (Remineralizing agents and time intervals). Labial enamel surfaces were wet ground using SiC papers # 180,400,600,1000,1200- grits, then were embedded in acrylic resin. Bleaching gel was applied according to the manufacturers' instructions and rinsed according to the time recommended by the manufacturer. Different remineralizing agents were applied according to the tested time intervals which are 2 days, five days, seven days, fifteen days and thirty days on bleached enamel specimens G1: MI Paste Plus, G2: Remin Pro and G3: Clinpro White Varnish. The specimens were submitted to microhardness before and after bleaching and after remineralization; then representative specimens were evaluated using environmental scanning electron microscope. ANOVA was used to analyze the data. Results: Two-Way ANOVA revealed that the type of remineralizing agent and time intervals variable had significant effect on microhardness of bleached enamel (P=0.000). Conclusion: Carbamide peroxide based bleaching gels decrease enamel microhardness. Using remineralizing agents such as MI Paste Plus improve microhardness after 15 days while using Clinpro White Varnish and Remin pro improve microhardness in shorter period of time.