Cytotoxic effects of extracts of compomers

We have studied the cytotoxicity of 10 commercially available compomers. Extracts were taken in cell culture medium of non-cured, freshly-cured, and aged samples. Murine L-929 fibroblasts were exposed to the extracts for 24 h and the cytotoxicity was evaluated using dimethylthiazol diphenyltetrazolium (MTT) assay and neutral red uptake (NRU). Extracts were rated as severely, moderately, or slightly cytotoxic when the activity relative to controls was less than 30%, between 30% and 60%, or greater than 60%, respectively. Extracts of non-cured materials were rated severely toxic with both methods, with one exception. All but one freshly-cured material exhibited moderate to severe toxicity in both assays. Aged test specimens were rated moderately to severely toxic. Non-cured materials were generally more toxic than cured, with two exceptions. Aging and polishing the samples to remove non-polymerized surface film affected cytotoxicity to a varying degree. Curing reduced cytotoxicity in the MTT test from severe to moderate in 7 of 9 materials, but had relatively little effect in the NRU assay. Aging and polishing, however, had little effect on cytotoxicity evaluated by the MTT test, but markedly reduced cytotoxicity in NRU in 6 of 8 extracts. To conclude, extracts made from compomers used for dental fillings were found to be cytotoxic both before and after setting.