Microbeam analysis of dental amalgam reveals high mobility of mercury

Background:
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

Hugh H. Harris, Stefan Vogt, Haold Eastgate, Daniel G. Legnini, Benjamin Hornberger, Zhonghou Cai, Barry Lai, Peter A. Lay, Migration of mercury from dental amalgam through human teeth, J. Synchrotron Radiat., 15/2 (2008) 123-128. DOI: 10.1107/S0909049507061468


Related studies

Lars Bjorkman, Birgitte F. Lundekvam, Torgils Laegreid, Bjorn I. Bertelsen, Inge Morild, Peer Lilleng, Birger Lind, Brita Palm, Marie Vahter, Mercury in human brain, blood, muscle and toenails in relation to exposure: an autopsy study, Environ. Health, 6 (2007) 30. DOI: 10.1186/1476-069X-6-30

Claudio Minoia, Anna Ronchi, Raffaella Gaggeri, Gianpaolo Guzzi, Gianluca Severi, Correlating blood mercury and dental amalgams, Sci. Total Environ., 381/1-3 (2007) 331. DOI: 10.1016/j.scitotenv.2007.02.022

Gianpaolo Guzzi, Marco Grandi, Cristina Cattaneo, Stefano Calza, Claudio Minoia, Anna Ronchi, Anna Gatti, Gianluca Severi, Dental Amalgam and Mercury Levels in Autopsy Tissues: Food for Thought, Am. J. Forensic Med. Pathol., 27/1 (2006) 42-45. DOI: 10.1097/01.paf.0000201177.62921.c8

B.A. Dye, S.E. Schober, C.F. Dillon, R.L. Jones, C. Fryar, M. McDowell, T.H Sinks, Urinary mercury concentrations associated with dental restorations in adult women aged 16-49 years: United States, 1999-2000, Occup. Environ. Med. , 62 (2005) 368-375. DOI: 10.1136/oem.2004.016832

  M. Bates, Jackie Fawcett, Nick Garrett, Terry Cutress, Tord Kjellstrom, Health Effect of Dental Amalgam Exposure: A Retrospective Cohort Study, Int. J. Epidemiol., 33 (2004) 894-902. DOI: 10.1093/ije/dyh164

J. Leistevuo, T. Leistevuo, H. Helenius, L. Pyy, M. Osterblad, P. Huovinen, Dental amalgam fillings and the amount of organic mercury in human saliva, Caries Res., 35 (2001) 163-166. DOI: 10.1159/0000474450

F. Lorscheider, M. Vimy, A. Summers,  Mercury exposure from "silver" tooth fillings: emerging evidence questions  a traditional dental paradigm, FASEB, 9 (1995) 504-508. DOI: 10.1096/fasebj.9.7.7737458

H.A. Lyttle, G.H. Bowden, The level of mercury in human dental plaque and interaction in vitro between biofilm of Streptococcus mutans and dental amalgam, J. Dent. Res., 72 (1993) 1320-1324. DOI: 10.1177/00220345930720091101

U. Heintze, S. Edwardsson, T. Derand, D. Brikhed, Methylation of mercury from dental amalgam and mercuric chloride by oral streptococci in vitro, Scand. J. Dent. Res., 91/2 (1983) 150-152. DOI: 10.1111/j.1600-0722.1983.tb00792.x

last time modified: November 1, 2024