Content and release of bisphenol A from polycarbonate dental products

Bisphenol A (BPA) is an endocrine disruptor, and is used as a raw material for bisphenol A diglycidyl methacrylate and polycarbonate, that are used in the dental materials. In this study, the total and released amounts of BPA from polycarbonate-based dental materials were measured with high-pressure liquid chromatography (HPLC). The specimens used were orthodontic brackets and denture base resins in the same condition as when obtained commercially were cut into 3 x 3 x 4 mm pieces and crushed into powder. The HPLC analysis was carried out after immersion of the specimens in water or ethanol for a determined time. The total amount of BPA in the specimens was analyzed after dissolution in chloroform. The amount of BPA released after immersion in water for 1 hr was 0.01-0.4 microgram/g for the block samples and 0.14-4.22 micrograms/g for the crushed samples, while that in ethanol for 1 hr was 0.12-9.42 micrograms/g for the block samples and 0.42-22.24 micrograms/g for the crushed samples. The control of BPA in the denture preform resin was 78.9 micrograms/g and this increased to 90.2 micrograms/g after heating to form dentures and then to 250 micrograms/g with mechanical crushing. The results of this study indicate that BPA is released from polycarbonates used in dentistry, and that the thermal conditions during the manufacturing of restorations may cause polymer decomposition resulting in the formation of BPA.