Triethylene glycol dimethacrylate (TEGDMA) is a dentin-bonding agent and a major component of various dental restorative biomaterials. TEGDMA monomers are released from dental resins and induce dental pulp inflammation and necrosis. In this study, we have investigated the mechanism of TEGDMA-induced cytotoxicity of fibroblasts. Treatment of cultured human gingival and pulpal fibroblasts with 0.1-3 mM of TEGDMA for 24 h induced a concentration-dependent and variable cytotoxic effect. Fifty percent of toxicity (TC(50)) was obtained with 1.2 +/- 0.9 and 2.6 +/- 1.1 mM of TEGDMA for gingival and pulpal fibroblasts, respectively. Moreover, TEGDMA-induced cytotoxicity was associated with an early and drastic depletion of cellular glutathione (GSH), which started at 15-30 min and was almost complete at 4-6 h. Antioxidants, such as Trolox (0.01 mM), ascorbate (0.2 mM), and N-acetylcysteine (NAC) (5 mM) prevented the TEGDMA-induced cytotoxicity while GSH depletion was partially inhibited. Finally, a late production of reactive oxygen species (ROS) occurred in fibroblasts treated with TEGDMA for 3-4 h, as determined by 2',7'-dichlorofluorescein fluorescence, and was completely inhibited by Trolox (5 microM). The data show that TEGDMA induced a drastic GSH depletion followed by production of ROS, which may contribute to the toxicity of gingival and pulpal fibroblasts. Antioxidants, such as NAC, ascorbate, and particularly Trolox, appear useful in preventing cell damage mediated by resin-containing dental restorative materials.

Eight biomaterials eluted from four different types of dental restorative biomaterials, that is, from glass-ionomer cement (GIC: Ketac-fil and Fuji II), resin-modified glass ionomer cement (RM-GIC: Fuji II LC and Photac-fil), composite (Z100 MP and Tetric-flow), and compomer (Compoglass F and F-2000), were studied for their cytotoxic properties in relation to glutathione (GSH) content in cultured human gingival fibroblasts. Z100 MP, Tetric-flow, and Compoglass F were less cytotoxic than the others, with a toxic concentration of 50% (TC 50) > 24% (of eluate), as determined by the MTT test. F-2000, Tetric-flow, and the other biomaterials were relatively more cytotoxic (TC 50 = 9-16%). With the exception of Z100 MP, all the biomaterials induced a depletion of cellular glutathione (GSH) that was variable depending upon the biomaterial eluates. The strongest GSH depletion was with F-2000, Fuji II, and Photac-fil. GSH depletion, with Compoglass and F-2000, was rapid-detectable after one h of cell treatment and complete within 3 h-whereas a longer period of incubation was required for the other biomaterials. Interestingly, the drug cytotoxic effects induced by all the biomaterials were prevented by cell treatment with the antioxidant N-acetylcysteine (NAC). This study provides evidence that the cytotoxic property of dental restorative biomaterials is associated with depletion of the glutathione level in gingival fibroblasts. While the molecular mechanisms of this phenomenon require further investigations, our data suggest that NAC may be useful in preventing the cellular damage induced by dental restorative biomaterials.