Issue V17N03 | Year 2020 | Editorial Research article | Pages 172 to 185
Objective: to evaluate, in vitro, the effect of calcium-supplemented bleaching gels on enamel at initial stage of erosion regarding the bleaching efficacy and surface microhardness. Materials and Methods: Bovine specimens (4x4mm) were randomized into 5 groups (n=12): G1 – without bleaching (control group), G2 – 35% hydrogen peroxide (HP) without calcium, G3 – 35% HP with calcium, G4 – 7.5% HP without calcium and G5 – 7.5% HP with calcium. The specimens were stained with black tea solution for 6 days and eroded in 0.01M HCl solution, pH 2.3 under continuous shaking (50 rpm) for 30 seconds. Bleaching of groups G2 and G3 was performed in two sessions with 7 days of time interval. Groups G4 and G5 were daily bleached during 14 days for 1 hour. Color analyses (ΔL, Δb and ΔE*ab) and surface microhardness (KHN) were performed in the initial and final times. Data were submitted to ANOVA and Tukey’s test (α=0.05). Results: For ΔL, Δb and ΔE*ab no statistical differences were found between the bleaching agents. The 7.5% HP with calcium showed less microhardness after bleaching and differed statistically between the initial and final times. The 35% HP with calcium showed higher microhardness among the bleaching gels. Conclusions: Calcium supplementation of bleaching gel did not interfere with the bleaching efficacy. The 35% HP bleaching gel with calcium resulted in less change of surface microhardness of enamel at initial stage of erosion.
Francisco MJV, Silva BG, Ferraz LN, Pereira R, Aguiar FHB, Lima DANL. Influence of bleaching gels containing calcium on dental enamel in early erosion stage. J Clin Dent Res. 2020 Sept-Dec;17(3):172-85.