Methods: Different mixes of endodontic filling materials, Zinc oxide (ZnO)+eugenol , Ca(OH)2+formocresol (FC), Ca(OH)2+ Iodoform+deionized water Ca(OH)2+ Iodoform + camphorated parachlorophenol (CPC), Ca(OH)2+CPC and Vitapex, were prepared as experimental groups and used to fill in special glass rings and subsequently eluted in 10mL of cell-culture medium at 37 °C, in a 5% CO2-in-air atmosphere and for a period of 24h. A cell culture medium was used as control group. DNA-fragmentation assay was performed to determine the genotoxicity. The level of Cox-2 protein expression, the extent of dental material-elicited inflammation of U2OS cells and the degree of MAPK kinase expression were determined by means of western-blotting analysis.
Results: The results revealed that no DNA breakage was apparent subsequent to U2OS cells having been treated with materials. Cox-2 band expression for ZnOE+FC group declined dramatically as compared to the control group, although for Ca(OH)2 + FC group and Ca(OH)2 +Iodofrom+CPC group a high level of expression of the Cox-2 band was noted. The band level of ERK (ERK-1, and ERK-2) kinase expression declined for ZnOE+FC group and Ca(OH)2 +CPC group as compared to the control group. p53 and Caspase-3 protein bands appeared for all experimental groups.
Conclusion: The cytotoxic mechanism of U2OS exposure to endodontic filling materials was induced by means of the activation of the p53 and caspase-3 apoptosis signaling pathways.