Test of long-term corrosion of dental amalgams

Seven non-gamma 2-amalgams and one conventional amalgam were used in the study. Cylindrical specimens were kept in a test solution for 1 yr. The depth of corrosion was measured and leakage of copper, zinc and mercury was determined by atomic absorption spectrophotometry. EDX was used to analyze the corrosion products. The results showed that copper leakage from the non-gamma 2-amalgams was higher than from the conventional amalgam. The amount of copper in the solution was not related to the concentration in the alloy. Dissolution of this ion was low during the last 6 months of the experimental period. Mercury leakage was comparatively low for all tested amalgams but the rate seemed to be less time dependent and leakage probably had not stopped after 1 yr. The depth of corrosion in the amalgams was in the range 100-500 micron. Under the experimental conditions the non-gamma 2-amalgams were more corroded than the conventional amalgam.