Objectives: A strategy for the evaluation of genotoxic activities of dental materials includes the analysis of various genetic endpoints (ISO 10993-3 and ISO 7405). The investigation of the formation of micronuclei in mammalian cell cultures is an alternative method to the cytogenetic chromosomal aberration assay. In the present study, four oxiranes and four Siloranes were tested for the formation of micronuclei in V79 Chinese hamster lung fibroblasts. Methods: The cells were cultivated in MEM supplemented with 10% FBS, penicillin (100 U/ml) and streptomycin (100 µg/ml) and seeded onto microscopic glass slides. Cell cultures were continuously exposed to various concentrations of the chemicals for 24 hours at 37 °C. Exposure was stopped by discarding the exposure medium, and DNA-containing structures (nuclei and micronuclei) were visualized after staining with SCHIFF reagent. Micronuclei were analyzed microscopically in 1000 cells/slide of three replicate cultures per concentration in two independent experiments. Results: The oxiranes di(cyclo hexene epoxide methyl)ether, epoxy cyclohexyl methyl-epoxy cyclo-hexane carboxylate (K-126), and bisphenol A-diglycidyl ether (BADGE) induced dose-related increases in micronuclei frequencies. The number of micronuclei in cell cultures treated with 0.03 mMol/L BADGE were 2-fold higher compared with control cultures, and K-126 was about twice as effective. Di(cyclo hexene epoxide methyl)ether was the most reactive molecule. The number of micronuclei in cell cultures exposed to 0.01 to 0.03 mMol/L di(cyclo hexene epoxide methyl)ether were 5- to 10-fold higher compared with control cultures. Di-3,4-epoxy cyclohexylmethyl-dimethyl-silane, was similar effective than BADGE, but 1,4-bis(2,3-epoxypropyloxypropyl-dimethylsily)benzene caused only very weak effects at low concentrations. No activity was observed with the other Silorane molecules, methyl-bis[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]phenyl silane and 1,3,5,7-tetrakis(ethyl cyclohexane epoxy)-1,3,5,7-tetramethyl cyclotetrasiloxane (TETS). Conclusions: Our findings clearly indicate a differential induction of micronuclei in mammalian cells by oxiranes and Siloranes under physiological conditions in vitro. Supported by the Bundesministerium für Bildung und Forschung (03N4001B/2).

Back to the Dental Materials: VIII - Others-Non-metallic Program
Back to the IADR/AADR/CADR 80th General Session (March 6-9, 2002)

Top Level Search