Amalgam dental

Density gradient Dental alloys Dental amalgam Dental amalgams Dental caries... 

Dentistry. Mercury is used in dental amalgams for fillings in teeth (see Dental materials). Dental uses have accounted for 2—4% of total U.S. mercury consumption since 1980 and generally 3—6% before that time (3). Dental amalgams used to fill cavities in teeth are approximately 50% mercury by weight. Dental use of mercury can be expected to continue to decrease, in part because of more effective cavity prevention as well as development and increasing use of alternative dental materials such as plastics and ceramics, and increasing awareness of the environmental and health effects of mercury. 

Dental amalgams, mainly silver—tin—mercury alloys, have been used as fillings for many years (see Dental MATERIALS). The most common alloy contains 12 wt % tin. 

Composition. The composition of powdered alloys used in preparing dental amalgams usually includes 66.7—75.5% silver 25.3—27.0% tin ... 

Gallium-Based Alloys. A gaUium-based alloy has been kitroduced commercially ki Japan as a substitute for dental amalgam, but similar alloy types have previously been associated with abnormal cellular reactions and are not much used elsewhere nickel— gallium alloys have produced carckiomas ki rats (139). The corrosion resistance of the gallium alloys is also marginal. 

There have been numerous reports of possible allergic reactions to mercury and mercury salts and to the mercury, silver and copper in dental amalgam as well as to amalgam corrosion products Studies of the release of mercury by amalgams into distilled water, saline and artificial saliva tend to be conflicting and contradictory but, overall, the data indicate that mercury release drops with time due to film formation and is less than the acceptable daily intake for mercury in food . Further, while metallic mercury can sensitise, sensitisation of patients to mercury by dental amalgam appears to be a rare occurrence. Nevertheless, there is a growing trend to develop polymer-based posterior restorative materials in order to eliminate the use of mercury in dentistry. 

Wing, G., Dental Amalgam , in Scientific Aspects of Dental Materials, (Ed.) J. A. von Fraunhofer), Butterworths, London (1975)... 

Okabe, T. Mercury in the Structure of Dental Amalgam , Dental Materials, 3, 1-8 (1987)... 

Do Due, H., Meyer R. M. and Tissot, P. Electrochemical Behaviour of SngHg (gamma-2) and Dental Amalgam in a Phosphate Buffer Solution , Electrochimica Acta, 25, 851-6 (1980)... 

Sarkar, N. K., Osborne, J. W. and Leinfelder, K. F. In Vitro Corrosion and In Vivo Marginal Fracture of Dental Amalgams , Journal of Dental Research, 61,1262-1268 (1982)... 

Dental amalgam, a solid solution of silver and tin in mercury, is used for filling tooth cavities. Two of the reduction half-reactions that the filling can undergo are... 

Fracture toughness values for glass polyalkenoate cement vary from 0-25 to 0-55 MN (Lloyd Mitchell, 1984 Goldman, 1985 Lloyd Adamson, 1987). The values are generally higher than those found for the traditional dental silicate cement but lower than those found for anterior composite resins (Lloyd Mitchell, 1984 Goldman, 1985) and much lower than those for posterior composite resins and dental amalgams (Lloyd Adamson, 1987). 

These low values for flexural strength and fracture toughness compared with the values for composite resins and dental amalgams make the glass-ionomer cement less suitable than these materials in high-stress situations. 

Human intake of total mercury from the diet normally ranges between 7 and 16 pg daily (Schumacher et al. 1994 Richardson et al. 1995). Fish consumption accounts for much of this exposure in the form of methylmercury 27% of the intake, and 40% of the absorbed dose. Intake of inorganic mercury arises primarily from foods other than fish, and is estimated at 1.8 pg daily with 0.18 pg absorbed daily (Richardson etal. 1995). In certain areas of India, blood mercury concentrations of people who ate fish were three to four times higher than non-fish eaters (Srinivasen and Mahajan 1989). In some countries, mercury in dental amalgams accounts for 2.8 pg daily, equivalent to as much as 36% of the total mercury intake and 42% of the absorbed dose (USPHS... 

It is used for bearings, to plate electrodes, and to make pewter, Babbitt metal, and dental amalgams. 

Use consumer products, industry, dental amalgams, switches, thermometers Source mining, environment, workplace Recommended daily intake none (not essential)... 

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