Dent Mater 11:323-326, September, 1995 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIH Short-term changes in lymphocytes after placement of silver amalgam restorations in healthy subjects zyxwvutsrqpon Estrella Osoriol, Manuel Toledanol, Manuel Bravo2, Raquel Osorio’ zyxwvutsrqponmlkjihgf ‘Area of Dental Materials, and zArea of Preventive Dentistry, School of Dentistry, University of Granada, Granada, SPAIN ABSTRACT 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. Resu/ts.There was a greater change inT8 lymphocytes in experimental than in control subjects; increases in B, DR, NK, and CD45R lympho- cytes 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. INTRODUCTION zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA The biocompatibility of dental restorations made with amalgam has been debated since this material was introduced, and the controversy has become more intense in recent years (Weineret al., 1990). Mercury is a cellular and protoplasmic toxin that inhibits cell proliferation and destroys the cell membrane. This element stimulates peroxide metabolism by removing hydrogen atoms from inorganic compounds. It also precipitates proteins by binding to their sulfydryl group, reduces cellular RNA, and blocks enzymatic systems (Stidtler, 1991). A study in rats showed that the inhalation oflarge amounts of mercury mist, released during high-speed amalgam grinding, leads to the accumulation of this element in different organs and tissues (Cutrightet al, 1973). Some authors have suggested that mercury released from dental amalgam causes autoimmune diseases and other alterations in the immune system (Eggleston, 1984; Hanson, 1983; Huggins, 1984). One study raised the possibility that immune dysfunction was traceable to amalgam (Duxburyet al., 1982 1. A longitudinal study by Eggleston (1984) showed that the percentage of T lymphocytes decreased after placement and removal of a restoration. When the filling was replaced with a metal-porcelain crown, lymphocyte numbers increased. In a quasi-experimental, longitudinal pretest-post&t study of eight individuals, Giuliani et al. (1990) assessed the percentages of total, T3, T4, and T8 lymphocytes, and the T4A% ratio, before, 15 d and 60 d after the placement of an amalgam restoration. They concluded that the amalgam may have had cytotoxic effects, although this was difficult to show conclusively because the study included no control group, and no statistical analysis of the data was done. In a cross-sectional study of final-year dental (experimental subjects who received restorations 1 and medical students (controls), Eedyet al. (1990) found signilicant differences in total, T3, T4 and T8 lymphocytes, and suggested that amalgam was responsible for the increase in lymphocytes in dental students. In another cross-sectional study, Mackert et al. (1991) compared total lymphocytes and the percentages of T3, T4, T8, Nk and B lymphocytes in individuals with and without restorations, and used a questionnaire to obtain information on possible confounding variables such as colds and exogenous exposure to mercury. Multifactorial discriminant analysis failed to detect significant differences between the two groups, and these authors concluded that dental amalgam did not affect lymphocyte subpopulations. Because previous studies have reported contradictory results, and because of the methodological variations between studies, basic immunological techniques were used to analyze lymphocyte subpopulations in healthy individuals who received restorations. Serum immunoglobulin concentrations were also measured. The complement system was studied because its proteic nature may be affected by mercury. The purpose of this study was to evaluate the changes in lymphocyte subpopulations, serum imminoglobulin concentrations and the Dental hkHerials6epfember 1995 323