Mercury in Serum in Relation to Removal of Amalgam Restorations
Objectives: Dental amalgam fillings continuously release elemental mercury vapor, which is absorbed and distributed via blood. Another source of mercury is seafood, which contains organic mercury (methylmercury; MeHg). In studies of exposure to mercury released from amalgam fillings, it could be of importance to differentiate between organic and inorganic mercury by speciation analysis. The objective of this study was to gain knowledge about concentration of MeHg and inorganic mercury before and after removal of all amalgam restorations in relation to the number of tooth surfaces filled with dental amalgam.
Methods: 32 individuals (13 men and 19 women, mean age 52 (SD 7) years) participating in an observational study (Clinicaltrials.gov NCT01682278) had all amalgam fillings removed (mean number of amalgam surfaces 20.3; SD 10.9). Serum samples were collected at baseline before amalgam removal and at follow up 1 year after the last amalgam filling was removed. Total mercury in serum was determined by inductively coupled plasma mass spectrometry (ICP-SFMS), and MeHg was determined by gas chromatography - inductively coupled plasma mass spectrometry (GC-ICP-SFMS). Inorganic mercury was estimated by calculating the difference between concentration of total mercury and the concentration of MeHg.
Results: At baseline, the mean concentration of inorganic mercury and MeHg was estimated at 0.22 (SD 0.21) µg Hg/L and 0.42 (SD 0.29) µg Hg/L, respectively. At follow-up the concentration of inorganic mercury was below detection limit of 0.2 µg/L (Wilcoxon Signed Rank Test p<0.001). Concentration of MeHg was not changed (mean 0.47 (SD 0.36) µg Hg/L; p=0.560). At baseline there was a significant correlation between number of tooth surfaces filled with dental amalgam and inorganic mercury (Kendall’s Tau-b 0.317, p=0.014). The correlation with concentration of MeHg was not significant (Kendall’s Tau-b 0.208, p=0.098).
Conclusions: Speciation analysis could yield important information in biomonitoring studies of mercury exposure from amalgam fillings.