Effect of sample preparation on the in vitro genotoxicity of a light curable glass ionomer cement

The glass ionomer cement Vitrebond™ showed a clear genotoxic effect in the in vitro Mammalian Cell Gene Mutation Test (HPRT Test) with CHO cells as well as in the bacterial umu-test with Salmonella typhimurium TA1535/pSK1002. Both DMSO and Hamʹs F12 cell culture medium extracts according to ISO 10993-12 (Biological evaluation of medical devices—Part 12: sample preparation and reference materials, Geneva, Switzerland) exhibit a clear genotoxic effect in the umu-test. The effect is independent of the extraction volume in a range from 0.5 to 4 ml Hamʹs F12 cell culture medium. Subsequent extractions of Vitrebond™ showed no significant difference in the genotoxic response although weight loss and content of 2-hydroxyethyl-methacrylate dropped significantly. In vivo conditions of Vitrebond™ were simulated by extractions with artificial and collected human saliva. These extracts showed a clear genotoxic effect in the umu-test, even if only a few seconds of extraction time were applied. In conclusion, sample preparations for genotoxicity testing according to ISO 10993-12 reflect the in vivo conditions of Vitrebond™ applications. This seems to be mostly due to the hydrophilic nature of the genotoxic ingredients.