Cytotoxic Evaluation of Resin Composites Containing Bioactive Glass Fillers

Method: Dental composites (50:50 Bis-GMA/TEGDMA resin:72wt% Sr-glass) were produced containing different concentrations (0, 5, 10 and 15 wt %) of two sol-gel bioactive glasses, BAG65 (65%wt SiO₂, 31%wt CaO, 4%wt P₂O₅)  and BAG62 (62%wt SiO₂, 30%wt CaO, 4%wt P₂O₅, 4%wt F). Cytotoxicity was evaluated in three phases.  Group 1: extracts obtained from 7 day incubations of composite disks (117.8 mm² surface area/ml; cured with 12 J/cm²) in cell culture medium at 37º C. Undifferentiated pulp cells (OD-21) were exposed to dilutions of the original extracts for 3, 5, and 7 days. Group 2: fresh composites disks were incubated with OD-21 cells (n=5) for 2 days. Group 3: fresh disks were incubated in culture medium at 37°C for 7 days, then the extracted disks were incubated with OD-21 cells for 2 days. The cytotoxicity was evaluated using Alamar Blue assay. Groups (n=5) were compared with ANOVA/Tukey’s(α=0.05).

Result: Group A: extracts from all composites significantly reduced cell viability until a dilution of 1:8 or lower, where the extract became equal to the control (data not shown). Group B: all composites showed significantly reduced cell viability at two days (Figure; Alamar Blue absorbance normalized to control). Group C: no reduction in cell viability was observed for any composite(Figure).

Conclusion: The results from Group A and B show that the composites, independent of composition, had equivalent potency in terms of reducing the viability of the cells in culture.  Soaking the composites for 7 days before exposing them to cells proved that the “toxic” components had been extracted and the materials were no longer cytotoxic.  These results show that cytotoxicity of composites with and without BAG must be attributed to the release of residual monomers and is not related to the presence of the BAG.