ACTIVATION OF THE IMMUNE-SYSTEM AND SYSTEMIC IMMUNE-COMPLEX DEPOSITS IN BROWN-NORWAY RATS WITH DENTAL AMALGAM RESTORATIONS

Dental amalgam restorations are a significant source of mercury exposu re in the human population, but their potential to cause systemic heal th effects is highly disputed. We examined effects on the immune syste m by giving genetically mercury-susceptible Brown Noway (BN) rats and mercury-resistant Lewis (LE) rats silver amalgam restorations in 4 mol ars of the upper jaw, causing a body burden similar to that described in human amalgam-bearers (from 250 to 375 mg amalgam/kg body weight). BN rats with amalgam restorations, compared with control rats given co mposite resinous restorations, developed a rapid activation of the imm une system, with a maximum 12-fold increase of the plasma IgE concentr ation after 3 wks (p < 0.001; Mann-Whitney's test). LE rats receiving amalgam restorations showed no significant increase of plasma IgE (p > 0.05). After 12 wks, BN rats with amalgam restorations showed signifi cantly increased (p < 0.05) titers of immune-complex (IC) deposits in the renal glomeruli and in the vessel walls of internal organs. These rats also showed a significant (p < 0.05), from six- to 130-fold, incr ease in tissue mercury concentration in the concentration order kidney > spleen > cerebrum occipital lobe > cerebellum > liver > thymus, and the tissue silver concentration was significantly (p < 0.05) increase d from three- to 11-fold. Amalgam-implanted BN rats showed a significa nt (p < 0.05) increase in copper concentration in the kidney and splee n, and in kidney selenium concentration. We conclude that dental amalg am restorations release substantial amounts of their elements, which a ccumulate in the organs and which, in genetically susceptible rats, gi ve rise to activation of the immune system and systemic IC deposits.