The cytotoxicity of Epiphany root canal sealer at various concentrations from 25-800 microg/mL on human periodontal ligament (HPDL) fibroblasts was evaluated at 1, 3, and 7 days. Controls included untreated cells and cells treated with the vehicle for Epiphany suspension. Fibroblast viability was assessed by 2 methods, crystal violet staining in 24-well plates and the fluorescence-based CyQUANT Cell Proliferation Assay in 96-well plates. Significant cytotoxicity against HPDL fibroblast growth by Epiphany was both time- and concentration-dependent. On day 1, 800 microg/mL, the highest concentration of Epiphany, showed significant cytotoxicity (P < or = .001). By day 7, all concentrations greater than 25 microg/mL showed significant (P < or = .05) loss of viability. This study demonstrated increased Epiphany cytotoxicity with an increase in concentration or exposure time.