Amalgam Fillings

Ag+.Ag s obtained after having accounted for the second electrode by using equation (3.3). The activity is then obtained from the Nemst equation (equation (3.8)) as XAg = 0.68. The mole fraction and activity are the same for solid mixtures of this type, so the amalgam filling is 68 mol% silver. 

Mercury is mined predominantly as HgS in cinnabar ore and is then converted commercially to a variety of chemical forms. Key industrial and commercial applications of mercury are found in the electrolytic production of chlorine and caustic soda the manufacture of electrical equipment, thermometers, and other instruments fluorescent lamps dental amalgam and artisanal gold production. Use in pharmaceuticals and in biocides has declined substantially in recent years, but occasional use in antiseptics and folk medicines is still encountered. Thimerosal, an organomercurial preservative that is metabolized in part to ethylmercury, has been removed from almost all the vaccines in which it was formerly present. Environmental exposure to mercury from the burning of fossil fuels, or the bioaccumulation of methylmercury in fish, remains a concern in some regions of the world. Low-level exposure to mercury released from dental amalgam fillings occurs, but systemic toxicity from this source has not been established. 

Release of relatively large amounts of mercury vapor when amalgam fillings are drilled out may present an acute hazard worse than long-term exposure to trace levels of Hg. This paradox is reminiscent of the heightened hazard from airborne fibers when asbestos is removed from buildings. 

The lower limit of quantitation is 0.5 ng/L (parts per trillion). To measure such small quantities requires extraordinary care at every stage of analysis to prevent contamination. Mercury amalgam fillings in a worker s teeth can contaminate samples exposed to exhaled breath. 

Accidentally chewing on a stray fragment of aluminum foil can cause a sharp tooth pain if the aluminum comes in contact with an amalgam filling. The filling, an alloy of silver, tin, and mercury, acts as the cathode of a tiny galvanic cell, the aluminum behaves... 

Strassburg M, Schubel F. 1967. [Generalized allergic reaction caused by silver amalgam fillings], Deutsch Zahnarztuche Zeitschrift 22 3-9. (German). 

P12. Pizzichini, M., Fonzi, M., Gasparoni, A., Mencarelli, M., Rocchi, G., Kaitsas, V., andFonzi, L., Influence of amalgam fillings on Hg levels and total antioxidant activity in plasma of healthy donors. Bull. Group Int. Rech. Sci. Stomatol. Odontol. 43, 62-67 (2001). 

Hibberd AR, Howard MA, Hunnisett AG. Mercury from dental amalgam fillings studies on oral chelating agents for assessing and reducing mercury burdens in humans. J Nutr Environ Med 1998 8 219-31. 

Contrary to previous belief, measurable amounts of mercury escape from dental amalgam fillings in the form of vapor, ions, and abraded particles, and individuals who are accustomed to chew their food thoroughly are... 

Sandborgh-Englund G, Nygren, AT, Ekstrand J, Elinder CG. 1996. No evidence of renal toxicity from amalgam fillings. Am J Physiol... 

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