An International group of scientists studied the mobility of mercury implanted as amalgam fillings into human teeth.
Exposure to mercury from dental amalgams, with possible negative health effects, has generally been considered to occur via either erosion or evaporation directly from the surface of fillings, followed by ingestion and inhalation of elemental mercury. While there is no doubt about the mercury exposure from dental amalgam, the question of its toxicity and long-term side effects remains contentious. The new study:
Since the toxicity of mercury depends on its speciation and on its exposure route, it was the aim of the new study to evaluate the direct way of exposure via migration of mercury through the tooth directly into the active blood stream. X-ray fluorescence imaging has been used to determine quantitatively the spatial distribution of mercury and other elements (Calcium, Cooper and Zinc) in sections of human teeth that had been filled with amalgam for more than 20 years. X-ray absorption near-edge spectroscopy (XANES) was also employed to gain chemical information on the mercury species present in the teeth.
The results from XRF imaging indicate that mercury migrate from amalgam fillings and filling linings, through the dentine, and into the pulp of the tooth (subsequently replaced by secondary dentine some time after the filling), which has an active bloodstream. Localization of mercury in the calculus observed on the edge of the tooth distal to the filling may further indicate that Hg is also considerably mobile through the mouth, presumably dissolved by bacterial action in the saliva, or possibly via surface diffusion over the tooth surface.
Direct speciation analysis of mercury in tubules suggests some oxidation of elemental mercury to the divalent state, indicating that a secondary transport mechanism of divalent mercury may become important with time.
The scientists concluded that the detection of mercury in areas of the tooth that once contained an active bloodstream and in calculus indicates that both exposure pathways should be considered as significant. The original study
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