Bisphenol-A in Dental Sealants

After bottled water, dental sealants are the most common case of rumored bisphenol-A exposure. They are made mostly of a monomer called bisphenol-A glycidyl methacrylate, or bis-GMA, along with bisphenol-A dimethacrylate (bis-DMA), ethylene glycol dimethacrylate (EGDMA) and triethylene glycol dimethacrylate (TEGDMA). While many of these polymers contain bisphenol-A, it is important to note that bisphenol-A itself is not used in dental sealants.

The fear of bisphenol-A exposure from dental sealants was started by a study conducted by Nicolas Olea in 1996 at the University of Granada and Tufts University. Olea found that an hour after applying a variety of commercial dental sealants, the saliva of his test subjects contained between 90 and 931µg of bisphenol-A. Considering that the Reference Dose for BPA is only 50µg, the experiment appeared to raise a grave and legitimate concern.

However, this experiment has not been replicated with the same results. Two groups have attempted experiments using the same sealants, but recorded levels of BPA 10 and 250 times lower than those found by Olea. Additionally, both found that after 24 hours, there was no measurable amount of BPA in the blood and saliva of the subjects.

While the disparities between the results may appear irreconcilable, there are reasonable explanations. Many suggest that the equipment Olea used might have confused triethylene glycol dimethacrylate (TEGDMA) with bisphenol-A. Additionally, Olea used excessively large amounts of sealant, which might have caused leaching.While there is some risk of bisphenol-a exposure attributed to dental sealants, it is essentially negligible, as it does not come near the RfD value established by the EPA.