Effect of Surface Polishing on Mercury Release from Dental Amalgam After Treatment 16% Carbamide Peroxide Gel

This study evaluated the effect of surface polishing on mercury release fromdental amalgam after treatment with 16% carbamide peroxide gel.Materials and Methods: Ninety-six samples from two different amalgam brands wereprepared in truncated cone-shaped PVC polymer molds with an external surface area of195 mm². Half of the specimens were polished with green and red rubber, a brush and tinoxide paste at low speed. Samples were treated with 16% carbamide peroxide gel intubes containing 3 mL of carbamide peroxide gel and 0.1 mL of distilled water for 14 and28 hours. Subsequently, carbamide peroxide gel on the sample surfaces was rinsed awaywith 7.0 mL of distilled water until the volume of each tube increased to 10 mL. Themercury level of each solution was measured using the VAV-440 mercury analyzer system.Considering the surface area of each amalgam disc, mercury amounts were calculatedin μg ⁄mm². Data were analyzed using two-way ANOVA.Results: There were significant differences between the mean levels of mercury releasefrom polished vs. unpolished amalgam surfaces after treatment with 16% carbamide peroxide.Increasing the storage time from 14 to 28 hours did not result in significantchanges in the amount of mercury release. There was no significant interaction effectbetween amalgam surface polish and storage time statistically.Conclusion: Polished amalgam restorations release less mercury after treatment withcarbamide peroxide bleaching gel in comparison with unpolished amalgam restorations.