Immortalized mouse odontoblast cell line MO6-G3 application for in vitro biocompatibility testing

This study was designed to determine the usefulness of an established stable immortalized mouse odontoblast cell line (MO6-G3) for dental material biocompatibility testing. Using a standard toxicity assay based on cell respiratory activity, the response to MO6-G3 cells was compared to the mouse fibroblastic cell line, L929, presently used for dental materials testing. The dental resin monomer TEGDMA was used as the dental material for the assay.

Cell lines (1 x 10(3)/well) were plated in 96 well culture plates and grown in DMEM supplemented with 10% FCS, 100 units/ml each of penicillin and streptomycin, and 50 micrograms/ml ascorbic acid in an atmosphere of 95% air and 5% CO2. Cells were exposed to TEGDMA resin monomer covering a dose range of 1 x 10(-6) to 0.5 x 10(-3) M. Unexposed control cells, as well as cells exposed to the DMSO vehicle in which the TEGDMA was dissolved, were included in all assays. Cytotoxicity was evaluated by determining cell respiratory activity spectrophotometrically using the tetrazolium compound WST-1.

Statistical analysis by ANOVA using Tukey's method for pair wise comparisons as the post hoc test indicated toxic effects of TEGDMA at 1 x 10(-5) M in the odontoblast cell line MO6-G3. By contrast, the monomer produced no toxic effects on the L929 fibroblast cell line after 24 hours of exposure, over the entire concentration range tested. Furthermore, MO6-G3 cells exposed to a concentration of 0.5 x 10(-3) M were unable to recover from the effects of the exposure 48 hours after removal of the resin. MO6-G3 cells exposed to 1 x 10(-4) and 0.5 x 10(-4) TEGDMA recovered 40-50% and 75-80% of control respiratory activity respectively, 48 hours after removal of the resin. Respiratory activity by L929 cells exposed to all TEGDMA concentrations tested was not different from the vehicle control 48 hours after removal of the resin.