Effect of Bleaching Gel Containing ACP or Fluoride on Enamel

Objective: To determine effects of two professional, home-use bleaching gels containing either amorphous calcium phosphate (ACP) or fluoride and an in-office bleaching gel with an after-bleaching agent containing ACP on human enamel surface gloss and roughness. Methods: This laboratory study included three experimental groups (A: Night White ACP 16% CP; B: Opalescence PF 15% CP; and C: Zoom2 Chairside) and a control group. Forty extracted human molars and premolars (stored in NaN3 solution) were randomly divided into four groups (10/each). Each tooth was mounted in acrylic base. The bleaching treatment followed manufacturers' instructions. The samples were stored in pooled human saliva at 37°C between treatments. The visual enamel surface gloss was assessed using a custom visual enamel gloss guide, and the roughness was measured with a prophilometer (Ra). The within-treatment effects were analyzed using the one-way ANOVA or Kruskal-Wallis one-way ANOVA on ranks. Wilcoxon signed rank test was used to determine the before and after treatment effect. Results: The average Ra after bleaching remained the same for Group A; for Group C it decreased slightly. Both Group B and the control had an increase in Ra, and the Ra changes for groups A and C were statistically lower compared to that for the control (p<0.05). The average surface gloss of Group C remained the same after bleaching, while other three groups showed a light decrease, with Group A having the lowest and the control the highest. There were no significant differences in within- and between-treatment effects for the enamel gloss; however, the results were consistent and supportive to the surface roughness data. Conclusion: The bleaching gels containing ACP appear to provide a slightly smoother and glossier enamel surface compared to the control and the bleaching gel containing fluoride.