Effects of bleaching agents on surface roughness of different substrats

Objective:This study investigated, on 21 days, the effects of 10% carbamida peroxide and 37% carbamida peroxide (PC) and 35% hydrogen peroxide (PP) mixed with sodium perborate on the surface roughness of dental human enamel, composites resin, porcelain and glass-ionomer cement. Methods:One hundred and forty samples were divided in to 3 groups according to the bleaching agents: G1: PC 10% for 3h per day/21 days; G2: PC 37% for 1h per day/21 day; G3: PP 35% for 21 days changed every 7 days. The groups and substrats tested were as describe following: composite resin A110(3M) (G1.1 - G2.1); composite resin Z250 (3M) (G1.2 -G2.2); human dental enamel (G1.3- G2.3); Loritac EX porcelain (G 1.4 - G 2.4); zinc phosphate cement (G2.5-G3.1); glass cement Vitremer (3M) (G2.6- G3.2) and Vidrion (S.S.White) (G2.7-G3.3). All samples were stored in distilled water at 37¨¬ C during 21 days, experimental period. The surface roughness (Ra) was measured in each specimen before and after exposure to the bleaching agents using Surfcorder SE120. Data were analyzed by ANOVA followed by Kruskal-Wallis (þ =1%).Results: No significant change in the surface roughness of porcelain and composite resin was observed þ>1%). There were no significative difference (þ>1%) in G1 (10% carbamide peroxide). Surface roughness values increased significantly (þ<1%) on human enamel and Vidrion G2 (37% carbamida peroxide) and all G3 (35% hydrogen peroxide.Conclusions:Within the limitations of this study, caution should be exercised if a bleaching combined 35% hydrogen peroxide(PP) and Zinc Phosphate cement, glass ionomers Vitremer and Vidrion as used material at intracoronal isolating barrier in walking bleaching technique