AN ASSESSMENT OF ADULT EXPOSURE AND RISKS FROM COMPONENTS AND DEGRADATION PRODUCTS OF COMPOSITE RESIN DENTAL MATERIALS

Concerns have been expressed regarding the health risks posed by chemi cal exposures from dental restorative materials. Dental materials are exempted from the pre-market review provisions for medical devices in Canada and, therefore, information on the risks of potential chemical exposures arising from such materials is lacking. An assessment of com ponents and degradation products of the class of dental materials know n as composite resins was undertaken to provide such chemical exposure and risk information. A probabilistic assessment was undertaken of ad ult exposures to two principal components of composite resins-silica, bisphenol-A glycidylmethacrylate (BIS-GMA) - and two degradation produ cts of BIS-GMA - formaldehyde and methacrylic acid. Assuming that the Canadian adult population with fillings had only composite resin mater ials, results indicated that average exposures to formaldehyde and met hacrylic acid were 10,000 times and 1,600,000 times lower, respectivel y, than relevant reference doses. Worst case exposures were also well below applicable reference levels. Risks posed by exposures to BIS-GMA and silica could not be assessed due to a lack of published ingestion reference doses for these substances. Gaps in the data base relating to the risks posed by composite resin dental materials were discussed, particularly in reference to the recently reported estrogenic potenti al of other degradation products of BIS-GMA.