The effect of pre-heating on cytotoxicity and monomer elution from bulk-fill composites

Abstract

Due to the effect of pre-heating on the degree of conversion of composites and subsequent probability of effect on monomer elution and cytotoxicity. In this study, the effect of pre-heating of Bulk-fill composites was investigated on monomer elution and cytotoxicity. Methods: Three different types of resin composites were used including Tetric N-Ceram Bulk Fill, X-tra Fill and X-tra Base. 10 cylindrical samples were prepared from each resin composites. Before light curing, 5 samples were pre-heated until reaching 68˚C, then 5 other samples were polymerized at room temperature. After 24 hours, release of UDMA, TEGDMA and BIS-GMA monomers were measured by High-Performance Liquid Chromatography analysis. Cytotoxicity was assessed by MTT method on human fibroblasts. Data analysis was performed by two-way ANOVA test, Games-Howell and Sidak post hoc tests. Results: Pre-heating did not have any statistically significant effect on the mean values of UDMA, TEGDMA and Bis-GMA elution. The greatest amount of released Bis-GMA and UDMA was obtained from Tetric N-Ceram Bulk-fill composite. The greatest amount of released TEGDMA was obtained from X-tra Fill composite. X-tra Base composite showed the lowest amount of monomer release. There was no statistically significant difference between the mean percentage of cytotoxicity based on pre-heating, but the cytotoxicity of the studied composites was significantly different. The cytotoxicity of Tetric N-Ceram Bulk-fil composite was greater than that of the two other composites. The monomer eluates did not correlate to cytotoxicity. Conclusion: Pre-heating did not have any effect on monomer release from bulk-fill resin composites. Moreover, the amount and the type of monomers released from various bulk-fill resin composites were not similar.