Genotoxic Potential of Flowable Bulk-Fill Composite Resins

Methods: Three flowable bulk-fill materials [x-tra base (XB), Surefil SDR flow (SDR), Venus Bulk Fill (VB)] and one conventional flowable control composite resin [Tetric EvoFlow (TEF)] were used. Cylindrical composite specimens (diameter: 10 mm, height: 4 mm) were irradiated for 20 or 30 s with a LED curing unit at 1170 mW/cm². The upper (0 mm) and lower specimen surface (4 mm) were mechanically scraped, and eluates were prepared for each material, surface level and curing time. Genotoxicity assessment was carried out in human peripheral blood leukocytes using the alkaline comet assay and cytokinesis-blocked micronucleus assay. Differences in values of comet assay parameters were tested by one-way ANOVA followed by Tukey post-hoc analysis, whereas chi-square test was used for the results of the micronucleus assay (α = 0.05).

Results: Considering the results of the comet assay, eluates of materials polymerized for 30 s did not significantly affect the level of primary damage to DNA. When 20 s of light irradiation was applied, only TEF, at a depth of 4 mm, showed a significant increase in the percentage of DNA that migrated in the tail compared to the untreated negative control (3.6 ± 2.9 and 1.4 ± 1.7, respectively). In the micronucleus assay, none of the evaluated materials induced statistically significant formation of any of the scored chromatin abnormalities (micronuclei, nuclear buds and nucleoplasmic bridges).

Conclusion: Under the experimental conditions of the present evaluation, the amount of released residual monomers in eluates used for cell culture treatment was below the critical level needed to induce biologically significant DNA damages.

This study was supported by the Croatian Science Foundation.