Cytotoxicity of resin-based light-cured liner cements

Objective: The aim of the present in vitro study was to evaluate the cytotoxic effects of resin-based light-cured cements when applied on the immortalized odontoblast cell line MDPC-23. Methods: Forty round-shaped specimens were prepared with each of the following experimental materials: a resin-based MTA cement - TheraCal (TCMTA); a resin-modified glass-ionomer cement - Vitrebond (VIT); and a light-cured calcium hydroxide cement – Ultra Blend Plus (UBP). The specimens were placed in serum-free culture medium and incubated for 24 hours or 7 days (20 specimens per group) at 37°C with 5% CO₂ and 95% air. The cells (30.000 cells/cm²) were seeded in wells of 24-well dishes and incubated for 72 hours. After this period, the complete culture medium (DMEM) was replaced by the extracts obtained from every specimen. The cytotoxic effects were evaluated by using the MTT assay and the cell morphology was assessed in scanning electron microscope (SEM). The total protein expressed by the cells was also quantified. In the control group, fresh culture medium (DMEM) was applied on the odontoblast-like cells. Data from the MTT assay and total protein expression were submitted to Kruskal-Wallis tests complemented by Mann-Whitney at the preset level of significance of 5%. Results: At the 24-hour period the experimental materials TCMTA, VIT, and UBP decreased the cell metabolic activity by 31.5%, 73.5% and 71.0%, respectively. The total protein expressed by the cells in contact with VIT and UBP was significantly lower than TCMTA and DMEM (Mann-Whitney, p<0.05). At the 7-day period TCMTA, VIT, and UBP decreased the metabolic activity of the MDPC-23 cells by 41.0%, 75.0% and 61.1%, respectively. Conclusion: All the liner materials were toxic to the cultured odontoblast-like cells. Among the materials, the light-cured resin-based MTA cement presented the lowest cytopathic effects.