Risk Assessment of Bisphenol A Exposure from BisGMA-based Dental Materials

Method: BisGMA is manufactured from BPA in a multi-step process, and low residual levels of BPA may remain in the BisGMA used in dental products. Published information from several sources suggests that BisGMA typically contains < 2 ppm of residual BPA. Polymerized BisGMA does not appear to be subject to oral enzymatic or thermal degradation; therefore, the likely source of BPA from BisGMA is leaching of residual monomer.  The following exposure assumptions were used in the assessment scenarios: 1) the product contains a maximum of 15% BisGMA (w/w); 2) applied product weight is sufficient to restore 3 large molars in an adult or 1 large molar in a 10 year old child and 3) any leached BPA is completely absorbed by the dental patient. Exposure to BPA was estimated either by assuming that it was present in BisGMA at 2 ppm or by reference to published data for leachable concentrations. BPA exposure via leaching into saliva was calculated both on a worst-case short-term basis and on a longer-term basis and these estimates were compared to authoritative BPA toxicity reference values.

Result: The resulting margins of exposure (MOE) were greater than 10,000 for all scenarios considered.  

Conclusion: This assessment confirms the safety of BisGMA-based dental composites with respect to potential BPA exposure and supports their continued use in dentistry.