Synergistic interaction caused to human gingival fibroblasts from dental monomers

Objectives. The toxicity of monomers like bisphenol-A-glycidyldimethacrylate (BisGMA) and urethane-dimethacrylate (UDMA) to cells is well studied. In these studies solubilizers, which have a toxic potential, are used to dissolve the basic monomers in the aqueous medium. In these experiments it is not possible to confidently exclude a synergistic effect of basic monomers and solubilizers in cells. Moreover, less is known about the synergistic interaction between basic- and comonomers (triethyleneglycoldimethacrylate (TEGDMA); 2-hydroxyethylmethacrylate (HEMA)) in cells. We dissolved the basic monomers in the comonomers and incubated human gingival fibroblasts (HGFs) with these binary mixtures in different concentrations. Methods. Proliferating HGFs monolayers were cultured in the absence or presence of mixtures of BisGMA/TEGDMA, BisGMA/HEMA, UDMA/TEGDMA and UDMA/HEMA. Twenty-four hours later XTT was added and the formazan formation was quantified. EC50 values were obtained at half-maximum-effect concentrations from fitted curves. Results. EC50 values were (mmol/l; mean +/- sem; n = 5): 0.01 BisGMA/0.48 TEGDMA; 0.04 BisGMA/4.99 HEMA; 0.04 UDMA/1.60 TEGDMA and 0.02 UDMA/2.26 HEMA. All tested mixtures induced a dose-dependent loss of viability in HGFs after 24 h. Significance. The EC50 values of binary mixtures were significantly (p < 0.05) lower compared to the EC50 values of the pure substances indicating a synergistic interaction of the mixtures on the HGFs. The widely used (co)monomers BisGMA and TEGDMA have the lowest EC50 values. The highest decrease of EC50 values, compared with the pure substances, were found in the mixture UDMA/HEMA. Worst case calculations show that the EC50 values from binary mixtures are at least 6 fold lower compared with known amounts of elutable (co)monomers from polymerized composites. (C) 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.