The effect of polymerization conditions on the amounts of unreacted monomer and bisphenol A in dental composite resins.

The aim of this study was to analyze the unreacted monomers of four commonly used composite resins, which were released after curing with different polymerization conditions. Four composite resins, consisting of two hybrid types and two flowable types from two manufacturers, were photopolymerized using different curing times and curing distances. After polymerization, samples were extracted for analysis at different time points up to 24 h. Released monomers were analyzed by reversed-phase liquid chromatography at UV 210 nm. Longer curing times and shorter curing distances resulted in higher polymerization rates and decreased release of TEGDMA and UDMA, but changes in curing time and distance had no significant effect on Bis-GMA. Release of BPA increased with increase in curing time or decrease in curing distance, in contrast to the results of TEGDMA and UDMA. Polymerization conditions need to be differently applied according to both monomer and resin types.