Mercury concentration in amniotic fluid and relation to amalgam fillings

Objectives: The aim of this study was to explore the relationship between the presence of detectable mercury concentration in amniotic fluid and the number and extent of amalgam restorations. Methods: Seventy-two pregnant women took part in this study, the total mercury concentration in amniotic fluid was determined. The dental status, the presence, the number and extent of amalgam fillings was charted. Mercury was determined in digested samples using automatic cold-vapor atomic absorption equipment (FIAS). Associations between amniotic mercury concentrations, number of dental amalgam fillings, health parameters, and food habits were examined calculating Pearson correlation coefficients (r) using listwise deletion of missing data. The set of explanatory variables was categorised and regression analysis procedure was performed using the concentration of mercury in amniotic fluid as dependent variable. Results: The mean Hgt concentration was 0.37±0.49 ng/ml. Nineteen subjects had a mercury concentration of 0 ng/ml. In cases with a concentration higher than zero the mean value was 0.49±0.52 ng/ml. The average number of fillings was 2.26±3.19 in the Hgt negative group and 5.32±3.03 in the Hgt positive (ANOVA one-way P=0.04). Statistically meaningful results are displayed for mercury concentration and presence and number of amalgam restorations, their extent and neurologic disease in the total sample (r=0.27, P=0.02; r=0.34 P=0.00; r=0.27 P=0.002; respectively). Regression analysis shows that mercury levels in amniotic fluid were related to the number and extent of amalgam restorations in Hgt positive group. Conclusions: A placement or a re-placement of an amalgam restoration during pregnancy should be taken into account.