The purpose of the study was to evaluate the sealing ability of a zinc oxide-eugenol, a modified zinc oxide-eugenol, and a resin endodontic sealer. One hundred thirty root canals of extracted human teeth were studied. Silver and gutta-percha points were cemented with either resin (Diaket), zinc oxide-eugenol (Tubliseal), or modified zinc oxide-eugenol (N2). The ability to seal the root canal space was evaluated with use of 45Ca isotope. One-day, three-month, six-month, and one-year intervals were chosen for study. The evaluation showed that Tubliseal with gutta-percha provided the best seal followed by TubliseaI with a silver point. Diaket was less effective in sealing ability than Tubliseal but more effective than N2. The purpose of the study was to evaluate the sealing ability of a zinc oxide-eugenol, a modified zinc oxide-eugenol, and a resin endodontic sealer. One hundred thirty root canals of extracted human teeth were studied. Silver and gutta-percha points were cemented with either resin (Diaket), zinc oxide-eugenol (Tubliseal), or modified zinc oxide-eugenol (N2). The ability to seal the root canal space was evaluated with use of 45Ca isotope. One-day, three-month, six-month, and one-year intervals were chosen for study. The evaluation showed that Tubliseal with gutta-percha provided the best seal followed by TubliseaI with a silver point. Diaket was less effective in sealing ability than Tubliseal but more effective than N2.