A study by Olea et al in 1996 reported quantities of specific estrogenic compounds, Bisphenol A (BPA), bis-glycidyl methacrylate (bis-GMA) and Bis-A-dimethacrylate (bis-DMA) in saliva associated with the placement of certain dental sealants. This report raised concern regarding the safety of dental sealants and composite restorations. In a subsequent study bis-GMA was found to be stable, but bis-DMA was shown to hydrolyze to BPA, which likely accounts for the BPA detected in extracts from certain sealants. Another study reported detectable amounts of triethylene glycol dimethacrylate (TEGDMA) and BPA diglycidyl ether (BADGE) were released from sealants into saliva. All of these compounds have been shown to have deleterious effects for specific endpoints in vitro and various endocrine disruptive effects in some animal models, although results have not been consistent across animal strain, mode of administration, diet and other unknown factors. Detectable levels in plasma have not been shown.

Since there are insufficient data on the leachability concentrations in body fluids of these compounds associated with composite fillings in humans it is important to determine whether or not there are detectable levels of these compounds associated with the placement of composite restorations, and if so, whether the levels are sufficiently below the maximum acceptable or reference dose established by the EPA. For bisphenol A the maximum acceptable dose is 0.05 milligrams per kilogram of body weight per day (US EPA, 1993).

The National Institute of Dental and Craniofacial Research, the National Toxicology Program of the National Institute of Environmental Health Sciences, and the Commissioned Officers Dental Clinic Dentists have a unique opportunity to conduct a collaborative investigation at the Commissioned Officers Dental Clinic (CODC) in Rockville, MD involving commissioned officers who need dental restorations. This study will determine whether or not the placement of composite restorations is associated with the presence of these compounds in saliva. This is particularly timely since the number of composite restorations placed by dentists practicing in the U.S is rapidly increasing with over 80 million composite restorations placed in 1999 (ADA, 2001). It is of relevance to the U.S. Public Health Service Commissioned Officers Dental Clinic (CODC) because the CODC places composite materials in its dental clinic and wants to ensure that commissioned officers are receiving the best and safest possible dental care.

The USAF was contacted and agreed to collaborate in our study by adding a second site using the identical protocol. This allowed for a large sample size but also provided us with a cohort of younger adults as well as some older adults to complement the middle aged cohort recruited at the CODC in Rockville.