Short-term changes in lymphocytes after placement of silver amalgam restorations in healthy subjects

Objectives. The purpose of this study was to evaluate the changes in lymphocyte subpopulations that have led to immune system alterations after amalgam restorations were placed. Methods. A controlled, quasi-experimental pretest-posttest design was used to investigate the immune effects of silver amalgam restorations in a sample of 60 individuals (30 experimental and 30 control subjects) aged 18 to 21 y. Two blood samples were obtained 15 d apart from each participant. In each experimental subject, two amalgam restorations were placed in posterior teeth immediately after the first blood sample was collected. The changes in lymphocyte subpopulations in the two groups were compared by multivariate analysis. Results. There was a greater change in T8 lymphocytes in experimental than in control subjects; increases in B, DR, NK, and CD45R lymphocytes were smaller in experimental than in control subjects; the changes in T3 and T4 lymphocytes did not differ significantly between the two groups. Significance. Despite the statistical significance of some differences between the two groups, the differences are not considered to be clinically relevant for the 2 wk time period after placement.