In vitro cytotoxicity of a new epoxy resin root canal sealer

The cytotoxic effects of a new epoxy resin-based root canal sealer (AH-plus), together with those of two other commonly used endodontic sealers (AH26 and zinc oxide-eugenol), have been studied in vitro on a culture of human gingival fibroblasts. Cytotoxicity was assessed by direct incubation of sealers' extracts with the cultured fibroblasts at different time intervals. Morphological and cytotoxic effects of the sealers were evaluated microscopically and spectrophotometrically using the neutral red cytotoxicity assay. Our results demonstrated that the cytotoxic effects induced by zinc oxide-eugenol were detectable as early as 1 hr after mixing and remained at a high level until completion of the experiment (5 wk). AH26, however, induced early cytotoxic effects that lasted for 1 wk, followed by a substantial reduction in cytotoxicity. Cytotoxicity of the AH-plus was confined to the early period of experiment and was no longer detectable after 4 hr of mixing. Comparison between the results obtained for each sealer revealed significant differences at particular time intervals. Our findings suggest the potential advantage of this sealer over the other two sealers.