Cytologic effects of primary tooth endodontic filling materials

Background/purpose: Primary tooth endodontic filling materials should be biocompatible with periodontal tissue. The purpose of this study was to analyze the biologic effects of different endodontic filling materials for primary teeth on a human osteosarcoma cell line (U2OS). Materials and methods: Experimental groups comprised different mixes of endodontic filling materials: zinc oxide-eugenol (ZnOE)+formocresol (FC); calcium hydroxide [Ca(OH) 2]+FC; Ca(OH)2+iodoform+deionized water; Ca(OH) 2+iodoform + camphorated parachlorophenol (CPC); Ca(OH) 2+CPC; and Vitapex. These were prepared and used to fill special glass rings, which were subsequently eluted in 10 mL of cell culture medium at 37°C in a 5% carbon dioxide-in-air atmosphere for 24 hours. Cell culture medium alone was used as the control group. A DNA fragmentation assay was performed to determine the genotoxicity of each mix of materials. The level of cyclooxygenase (COX)-2 protein expression, the extent of dental materialelicited inflammation of U2OS cells, and the degree of mitogen-activated protein (MAP) kinase expression were determined using Western blot analysis. Results: The results revealed that no DNA breakage was apparent after U2OS cells were treated with the various materials. COX-2 band expression dramatically declined in the ZnOE+ FC group compared with the control group, although high levels of expression of the COX-2 band were noted for the Ca(OH)2+FC and Ca(OH)2+iodo-form+CPC groups. Band levels of extracellular signal-regulated kinase (ERK-1 and ERK-2) expression declined in the ZnOE+FC and Ca(OH)2+CPC groups compared with the control group. p53 and caspase-3 protein bands appeared in all experimental groups. Conclusion: The cytotoxic mechanism of endodontic filling materials on U2OS cells was induced by means of activation of the p53 and caspase-3 apoptosis signaling pathways.