Genotoxicity evaluation of locally produced nano-hydroxyapatite-silica: An in vitro study using the bacterial reverse mutation test

Background: Nanohydroxyapatite-silica (nanoHA-Silica) has been produced by one-pot sol-gel technique. The material when incorporated into commercial Glass Ionomer Cement (GIC) was found to exhibit higher Vickers hardness, compressive strength, and flexural strength compared to conventional GIC. However, before starting to be used and exposed to the human cell, every material product should undergo for genotoxic evaluation. Thus, the objective of this in vitro study was to evaluate the genotoxicity of locally produced nanoHA-Silica under bacterial reverse mutation assay (Ames test). Materials and Methods: Four Salmonella typhimurium strains TA98, TA102, TA1535, and TA1537 were incubated with nanoHA-Silica in the presence and absence of exogenous metabolic activation system (S9) at five different concentrations (0.3125, 0.625, 1.25, 2.5, and 5 mg/plate) along with appropriate positive and negative controls. The assessment of the results was based on the number of revertant colonies in each plate, and the results were regarded as mutagenic when the number of revertant colonies was more than two-fold of the negative control. Results: There was no significant increase in the number of revertant colonies corresponding to the increase in the concentrations of the test substance for all the five bacterial strains treated with or without S9. Conclusion: NanoHA-Silica-GIC was non-genotoxic and had no mutagenic potential under present test conditions.