In vitro biocompatibility testing of different base materials used for elevation of proximal subgingival margins using human gingival epithelial cells

Purpose: To analyze the biological effects of four base materials used for elevation of proximal subgingival margins on gingival epithelial cells. Methods: Twenty-eight specimens for each of the four base materials (total 112 specimens) were used: resin-modified glass ionomer (RMGI), glass hybrid (HV-GIC), flowable bulk fill resin composite (Bulk Flow) and bioactive ionic resin (Activa). Proximal enamel and root dentin were used as controls. Gingival epithelial cell viability was calculated after direct incubation on all four types of material for either 24 h or 72 h using both the methyl tetrazoliwn and trypan blue dye exclusion assays. Data were analyzed statistically using one-way analysis of variance, Tukey post hoc test and independent sample t-test (P < 0.05). Results: Cell viability values in both assays showed significant differences among the study groups. Bulk Flow showed the highest values, followed in order by Activa and the control groups. Both HV-GIC and RMGI had the lowest values. Cell viability in all of the study groups was higher after incubation for 72 h than after 24 h. Conclusion: In terms of biocompatibility with epithelial tissues, bulk fill resin composite appears to be most suitable, followed by bioactive composite, for subgingival placement than glass ionomer-based materials, especially that containing 2-hydroxy-ethyl methacrylate.