Bisphenol-A content of resin monomers and related degradation products

Abstract

Recently, it was reported that Bisphenol-A (BPA) was released from one fissure sealant (Delton) into saliva causing estrogenic activity in vitro. The aim of this study was to chemically analyze the BPA content of different fissure sealant resin monomers and their release of BPA under hydrolytic conditions. BPA content was first measured in commercially available monomers of bisphenol-A glycidyldimethacrylate (Bis-GMA), bisphenol-A dimethacrylate (Bis-DMA) and bisphenol-A diglycidylether (BADGE). Then, Bis-GMA-monomer and Bis-DMA-monomer in methanol were subjected to pH values of 0 to 11 for 30 minutes at 50 degrees C, to porcine liver esterase, and to pooled saliva for up to 24 hours. The BPA-content was determined by high-performance liquid chromatography (HPLC). Bis-GMA-monomer and BADGE-monomer from one manufacturer did not contain any detectable amounts of BPA (< or = 2 ppm); Bis-DMA and BADGE-monomer from a second manufacturer contained BPA quantities of 4-155 ppm. For Bis-GMA-monomer, no BPA could be detected under any hydrolytic conditions chosen (detection limit: < or = 1%). For Bis-DMA-monomer an increase of BPA was observed at pH 11, resulting in a conversion of approx. 100% Bis-DMA to BPA. When Bis-DMA was subjected to esterase, a conversion of 82.5% resulted after 24 h; saliva led to an 81.4% conversion of Bis-DMA after 24 h. Hence, we conclude that the results reported in the literature may be attributed to the Bis-DMA-content of the fissure sealant tested (Delton). No BPA-release is expected under physiologic conditions from fissure sealants based on Bis-GMA if pure base monomers are used.

BPA from dental resin material: where are we going with restorative and preventive dental biomaterials?

“…BPA was found in the saliva within few minutes after a dental treatment, but at considerably lower levels than previously reported. BPA became undetectable 1 and 24 h after the placement of the sealant [10,12]. It was concluded that due to the low level of BPA, there was no clinical risk after placement of fissure sealants, an assumption that was confirmed by other authors [10,13,14].…”

“…BPA became undetectable 1 and 24 h after the placement of the sealant [10,12]. It was concluded that due to the low level of BPA, there was no clinical risk after placement of fissure sealants, an assumption that was confirmed by other authors [10,13,14]. Indeed, considering the dose-response, the BPA level was too low to be toxic if the disease is linked to the amount of BPA released during dental treatment.…”

“…Again, these data depend upon the sensitivity of the analytical method. However, it could be clarified that Bis-DMA containing resins rather than Bis-GMA-based resins released BPA shortly after placement and that collected saliva showed estrogenic activity in vitro [10][11][12]. Under hydrolytic conditions, the release of BPA from a fissure sealant into the saliva occurs immediately after the placement of the sealant.…”

Casting the runes

“…The concentration of released Bis-GMA from certain types of sealants has been reported to be within the range at which estrogen receptor-mediated effects were seen in rodents (Schmalz et al 1999). However, the release from resin based restoratives is much lower.…”

Comments on "Estrogenicity of Resin-Based Composites and Sealants Used in Dentistry"

“…Therefore, leaching of a small amount of unpolymerized BPDMA is likely (3,4). Furthermore, the detection of BPA derived from BPDMA in saliva is likely because BPDMA is easily hydrolyzed to BPA in saliva (6) Olea's Response…”