Migration of mercury from dental amalgam through human teeth

May 23, 2008

Harris HH, Vogt S, Eastgate H, Legnini DG, Hornberger B, Cai Z, Lai B, Lay

PA.

School of Chemistry, The University of Sydney, NSW 2006, Australia.

_hugh.harris@ adelaide. edu.au_ (hugh.harris)

J Synchrotron Radiat. 2008 Mar;15(Pt 2):123-8.

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.

The aim of this study was to determine the relative importance of the direct

migration of mercury through the tooth as an alternative exposure pathway.

X-ray fluorescence imaging has been used to determine quantitatively the

spatial distribution of Hg, Ca, Zn and Cu 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 present in the teeth. Hg (up to

approximately 10 mg g(-1)) and Zn (>100 mg g(-1)) were detected in the teeth

several

millimetres from the location of the amalgams. At high resolution, Hg showed

higher concentrations in dentinal tubules while Zn was generally evenly

distributed. XANES showed that the chemical form of Hg that had migrated into

the

tooth had been altered from that present in the amalgam. The differing spatial

distributions of Hg and Zn suggest distinct transport mechanisms for the two

metals, presumably chemical for Zn and initially physical for Hg. Subsequent

oxidation of Hg may lead to a loss of mobility or the development of a

secondary transport mechanism. Most importantly the detection of Hg in areas of

the

tooth that once contained an active bloodstream and in calculus indicates that

both exposure pathways should be considered as significant.

PMID: 18296776 [PubMed - indexed for MEDLINE]

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