The Effect of a 16% Carbamide Peroxide Gel on Mercury and Silver Ion Release from Admixed and Spherical Dental Amalgams

Abstract

The aim of this study was to investigate the effect of 16 percent carbamide peroxide gel on mercury and silver ions released from admixed and spherical dental amalgams. A total of 96 amalgam discs were prepared from two different types and brands of dental amalgam (admixed and spherical). The samples were stored at room temperature in glass tubes containing distilled water for 24 hours. The specimens were then polished and again immersed in distilled water at room temperature and stored for one month. Samples of both types of dental amalgam were treated with carbamide peroxide 16 percent gel (Nite White, Discus Dental, Inc., Culver City, CA, USA) for 14 and 28 hours (experimental group) and compared to samples not exposed to the bleaching agent but stored continuously in distilled water. Mercury and silver levels of each solution were measured using the VAV-440 analyzer system. Mercury and silver ions released from the experimental group were significantly greater than from the control group (p<0.001). There was no significant difference between the mean levels of mercury and silver ions in the two kinds of amalgams after treatment with 16 percent carbamide peroxide (p=0.119 for mercury and p=0.199 for silver). Increasing the storage time in the carbamide peroxide gel from 14 to 28 hours did not result in significant changes in the amount of ions released (p=0.329 for mercury and p=0.082 for silver). Also, the interaction effect between amalgam particles' shape (admixed and spherical) versus storage time (14 versus 28 hours) was not statistically significant (p=0.901 for mercury and p=0.951 for silver). Treatment with 16 percent carbamide peroxide gel increased mercury and silver ions released from admixed and spherical amalgams, compared to samples in the control group, but the difference between the two amalgams was not statistically significant. The amount of mercury and silver ions released from high-copper dental amalgams during bleaching with 16 percent carbamide peroxide is in the safe range of mercury intake for patients.