Dental Amalgam (Hansard, 23 July 1986)

§ Mr. Hayhoe

The advice of the Committee on Toxicity was as followsDental amalgams containing mercury have been used for 150 years and we understand that in the United Kingdom some 30 million amalgam restorations are inserted each year. Despite this extensive usage only a very few cases that can he recognised as having any reaction to mercury occur each year, and these are due to hypersensitivity. Nevertheless, from time to time concern is expressed in some quarters that use of dental amalgam may lead to excessive exposure to mercury and to poisoning. We have examined the evidence from which such concern arises. There is some evidence that mercury is released from dental amalgam during the period following insertion and on the removal of the restorations. Some mercury may be released as a result of corrosion but this is likely to be small because of the excess of unreacted alloy in the finished lilting. The development of copper enriched alloys has reduced the potential for corrosion. Vapourisation of mercury from amalgam restoration may possibly occur with prolonged heavy chewing. However, long term clinical evidence would seem to suggest the view that substantial amounts of mercury are not released from amalgam fillings. Theoretical considerations suggest that in extreme cases the amount of mercury released might, were it known to be absorbed, constitute an undesirable although not a toxic exposure. However, studies of the concentration of mercury in the blood of people with amalgam restorations indicate to us that the exposure is in fact of no toxiocological significance. It has been suggested also that exposure to mercury from amalgam may be a factor in the development of some chronic diseases, but in our opinion the evidence does not support this contention. In our opinion the use of dental amalgam is free from risk of systematic toxicity and only a very few cases of hypersensitivity occur. It is our view that further research in this area would not merit priority.