Effects of ethanol and DMSO on TEGDMA solubility and cytotoxicity

Objective: Several in vitro studies have been carried out to investigate the triethylenglycol-dimethacrylate (TEGDMA) cytotoxicity. However, these studies have never focused on how the solvents used to dissolve TEGDMA in the experimental conditions might influence monomer effective concentrations and in turn its cytotoxicity. Hence, the aim of this study was to evaluate the active concentrations of the TEGDMA over the routinely experimental conditions used in biocompatibility in vitro tests and to determine any changes in cytotoxicity depending on the TEGDMA solution composition. Methods: TEGDMA dilutions were prepared directly in DMEM (in absence of cells) or were dissolved previously in DMSO or ethanol and then in medium. Monomer concentrations were quantified by an HPLC system. The cytotoxicity effects of TEGDMA dilutions (1 and 2 mmol/L, with and w/o solvents) were evaluated on 3T3-fibroblasts by MTT assay. ROS production (by FACScan flowcytometer) and intracellular and extracellular TEGDMA concentration (by HPLC) were also determined. Data were analyzed by ANOVA followed by Turkey's test for multiple comparisons. Results: Maximum solubility of TEGDMA in DMEM (in absence of cells) was 0.5 mmol/L both in the presence and absence of solvents. 2 mmol/L TEGDMA - solubilized in DMSO or ethanol and then dissolved in medium - caused a significant decrease in cell viability and an induction of ROS production compared to the same TEGDMA concentration dissolved in medium directly. Moreover when 2 mmol/L TEGDMA was added to the cells in presence of DMSO and ETOH, after 2h of incubation, TEGDMA concentration was reduced respectively 10% and 20%, while, TEGDMA added without vehicles remains constant. Conclusions: Our results showed that TEGDMA solubilization in DMEM was not complete and that the cytotoxic effects of the monomer was influenced by the method of solubilization.