Harris Hugh H, Vogt Stefan, Eastgate Harold, Legnini Daniel G, Hornberger Benjamin, Cai Zhonghou, Lai Barry, Lay Peter A
School of Chemistry, The University of Sydney, NSW 2006, Australia.
J Synchrotron Radiat. 2008 Mar;15(Pt 2):123-8. doi: 10.1107/S0909049507061468. Epub 2008 Feb 19.
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.
牙科汞合金中的汞暴露可能对健康产生负面影响，一般认为其通过补牙表面的侵蚀或蒸发，随后被摄入而发生。本研究的目的是确定汞通过牙齿直接迁移作为一种替代暴露途径的相对重要性。X射线荧光成像已被用于定量测定填充汞合金超过20年的人类牙齿切片中汞、钙、锌和铜的空间分布。还采用了X射线吸收近边光谱法（XANES）来获取牙齿中汞的化学信息。在距离汞合金位置几毫米的牙齿中检测到了汞（高达约10毫克/克(-1)）和锌（>100毫克/克(-1)）。在高分辨率下，汞在牙本质小管中的浓度较高，而锌通常均匀分布。XANES表明，迁移到牙齿中的汞的化学形态已与汞合金中的不同。汞和锌不同的空间分布表明这两种金属有不同的传输机制，推测锌是化学传输，汞最初是物理传输。汞随后的氧化可能导致迁移性丧失或产生二次传输机制。最重要的是，在曾经有活跃血流的牙齿区域和牙垢中检测到汞，这表明两种暴露途径都应被视为重要途径。
