Abstract: Objective The purpose of this investigation to evaluate the clinical efficacy of mineral trioxide aggregate (MTA) as an apical barrier materital when used in teeh with incomplete root formation. Methods Twenty eight teeth with open apices in 28 patients were treated by standard endodontic procedures. An absorbable collagen sponge and MTA apical barrier were placed in the apical portion of the root canal under dental operating microscope (DOM) after a calcium hydroxide intracanal dressing had been applied for 1 week. The remainder of canal was back-filled with AH plus sealer thermoplastisized Gutta-Percha 1d following MTA placement and access cavity was restored with composite resin followed by all crown. Follow-up evaluations were carried out clinically and radiographically at 6-month and 1-year intervals. Results Sixty-five percent of these teeth were successful at 6-month appointment. Ninety-one percent of these teeth were successful at 1-year appointment. Periapical index scores at 6-month and 1-year recall appointments were improved. Chi-square test indicated that successful cases in recall times did significantly influence clinical outcome. Conclusions These results indicated that the mineral trioxide aggregate apical barrier technique is a successful method for treating teeth with immature apices.

Key words: Mineral trioxide aggregate, Apical barrier, open apices