The evaluation of the influence of using MTA in teeth with post indication on the apical sealing ability Tahsin Yildirim, DDS, PhD, a Tamer Tas ¸demir, DDS, PhD, b and Hasan Orucoglu, DDS, PhD, c Trabzon and Konya, Turkey KARADENIZ TECHNICAL UNIVERSITY AND SELCUK UNIVERSITY Objectives. The aim of this study was to evaluate the influence of using MTA in teeth with post-core indication and to compare it with the immediate or delayed post space preparation on the integrity of apical seal in teeth filled with gutta-percha and sealer. Study design. Fifty-one single-rooted freshly extracted human maxillary incisor teeth were selected. The crowns of the teeth were removed to a length of 14 mm and canals were prepared by using K-files with the step-back technique. The teeth were randomly divided into 3 groups of 15 specimens each. Group A was filled with gutta-percha and sealer using lateral compaction, and post space was prepared immediately using a heated instrument. Specimens in Group B were filled with the same materials as Group A and post space was prepared after 1 week with Gates- Glidden drills. Group C was filled with MTA as an apical 5-mm filling. In all groups, materials were left in the root canals at the apical 5-mm level. The remaining 6 teeth were used as controls. The microleakage values of each group were measured after 1 month, using a computerized fluid filtration method. Results. The MTA (Group C) showed less microleakage than immediate and delayed post space preparation methods (Group A, B) in 1 month, and this difference was found to be statistically significant (P  .005). Additionally, no statistically significant difference was determined between Group A and Group B (P  .05). Conclusion. These results suggest that MTA can be used in the root canals as apical filling material in teeth with post- core indication. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;108:471-474) The goal of obturation is to obtain a fluid-tight seal of the root canal system from its coronal aspect through its apical extent. 1 Inadequate obturation can result in the movement of oral fluids into voids in the obturated root canal and the induction of a periapical inflammatory reaction. 1,2 The integrity of the root canal filling in the apical few millimeters is believed to be one of the criteria neces- sary to ensure successful endodontic treatment. 3 The restoration of endodontically treated teeth often re- quires the use of intracanal posts, which fit into a space created by the removal of a portion of the filling ma- terial. 4 Post space is prepared after a root canal filling immediately or delayed. However, there is no consen- sus on the time interval between the root canal filling and the post space preparation. Kwan and Harrington, 5 Dickey et al., 6 Fan et al., 7 and Solano et al. 8 stated that the removal of gutta-percha immediately after a root canal filling results in less microleakage than delayed removal of gutta-percha, whereas Bourgeois and Lemon 9 and Madison and Zakariasen 4 stated that there is no difference between the 2 techniques in the post space preparation. Mineral trioxide aggregate (MTA) was developed to seal the pathways of communication between the root canal system and the external surface of the tooth. 10 MTA has good sealing property, 11 bactericidal effect, 12 and biocompatibility. 13,14 MTA has been used clini- cally as a retrograde filling material; for perforation repair; and in pulpotomy, pulp capping, and the treat- ment of teeth with open apices as an orthograde apical plug. 15 However, there is no study investigating whether MTA filling in the apical third of the root canal in teeth with post-core indication would be successful or not. The aim of this in vitro study was to evaluate the influence of using of MTA in teeth with post indication and to compare it with the immediate and delayed post space preparation on the integrity of the apical seal in teeth filled with gutta-percha and sealer. MATERIALS AND METHODS Fifty-one freshly extracted single-rooted human maxillary incisors were used in this study. Teeth with caries, cracks, or open apices were excluded, and their external surfaces were cleaned with curettes. The teeth a Department of Restorative Dentistry, Faculty of Dentistry, Kara- deniz Technical University, Trabzon, Turkey. b Department of Endodontics, Faculty of Dentistry, Karadeniz Tech- nical University, Trabzon, Turkey. c Department of Endodontics, Faculty of Dentistry, Selcuk University, Konya, Turkey. Received for publication Feb 3, 2009; returned for revision Apr 29, 2009; accepted for publication Apr 29, 2009. 1079-2104/$ - see front matter © 2009 Published by Mosby, Inc. doi:10.1016/j.tripleo.2009.04.036 471