Relation between mercury concentrations in saliva, blood, and urine in subjects with amalgam restorations

The aim was to determine the relationship between mercury content of resting and stimulated saliva, and blood and urine. Eighty subjects participated; 40 of them attributed their self-reported complaints to dental amalgam (patients), the others were matched with respect to age, sex and amalgam restorations (controls). Serum, 24-h urine, resting and chewing stimulated saliva were analyzed for mercury using the ASS-technique. Quality, number, surfaces and total area of amalgam fillings were recorded clinically and using study models. Median (range) mercury levels in serum were 0.67 (0.1-1.52) microgram/l for patients and 0.60 (0.1-1.3) for controls. In urine levels were found to be 0.77 (0.11-5.16) and 0.94 (0.17-3.01) microgram/g creatinine respectively. No significant differences were found between the groups. Resting saliva contained 2.97 (0.10-45.46) micrograms/l in patients and 3.69 (0.34-55.41) in controls (not significant). Chewing mobilized an additional amount of 16.78 (-6.97 to 149.78) micrograms/l in patients and 49.49 (-1.36 to 504.63) in controls (P < or = 0.01). Only a weak correlation was found between mobilized mercury in saliva and serum (r = 0.27; P < or = 0.05) or urine (r = 0.47; P < or = 0.001). For resting saliva the respective values were r = 0.45 (P < or = 0.001) and r = 0.60 (P < or = 0.001). Saliva testing is not an appropriate measure for estimating the mercury burden derived from dental amalgam.