JOURNAL OF ENDODONTICS Copyright © 2002 by The American Association of Endodontists Printed in U.S.A. VOL. 28, NO. 8, AUGUST 2002 Microleakage of Resected MTA Wallis E. Andelin, DDS, David F. Browning, DDS, G-Hong Robert Hsu, DDS, David D. Roland, DDS, and Mahmoud Torabinejad, DMD, MSD, PhD Forty-six single rooted extracted human teeth were used in this study. After cleaning and shaping, twenty canals were randomly selected for obturation with MTA placed in an orthograde manor (Group 1). Another twenty roots were obturated with gutta-percha and Kerr EWT sealer, using warm vertical compaction (Group 2). The apical 3 mm of each root in both groups were resected at approximately 45 degrees to its long axis. The teeth were aged for 48 h in a humidor. The rootends of the teeth in Group 2 were then prepared and received MTA as a root-end filling material to a depth of 3 mm. Six roots were used as positive and negative controls. The roots of all teeth were placed in contact with India ink for 48 h. The roots were split and examined for dye leakage. There was no discernible leakage in teeth with resected MTA or those with MTA placed as a retrograde root-end filling material. We found no significant difference in dye leakage between resected MTA (Group 1) and non-resected MTA (Group 2). Based on these results it appears that the resection of set MTA does not affect its sealing ability. The purpose of this study was to evaluate the effect of resection on the microleakage of MTA. MATERIALS AND METHODS Forty-six extracted human teeth were used for this study. The selection criteria were presence of a single root canal, root length of at least 12 mm, no evidence of previous root canal therapy, and an initial apical size no greater than ISO size 20. After access preparation each canal was instrumented to an ISO size 50 at 0.5 mm from the apical foramen and step-back filed to an ISO size 80. Five-and-one-quarter percent NaOCl was used as an irrigant during cleaning and shaping. After instrumentation the teeth were randomly divided into four groups. Twenty canals were obturated orthograde with MTA (Pro Root; Tulsa Dental, Tulsa, OK, U.S.A.) (Group 1). Twenty more canals were obturated with gutta-percha and Kerr EWT sealer (Kerr Dental, Orange, California, U.S.A.) using warm vertical compaction (Group 2). Three canals were also filled in the same manner as Group 2 to serve as negative controls. Three additional canals were filled with gutta-percha and no sealer and served as positive control samples. The teeth in all groups were then placed in a humidor for 48 h. The apical 3 mm of the root apex of each tooth from Group 1 was resected at approximately 45 degrees to its long axis. The coronal and lateral aspects of these teeth were then coated with two coats of nail varnish and allowed to dry. The root-ends were then submerged in India ink for 48 h. Following root-end resection of teeth in a manner similar to that of Group 1, root-end cavities were prepared with a 330 carbon-steel bur (Brasseler, Savannah, GA, U.S.A.) to a depth of 3 mm in the teeth in Group 2. MTA was then placed in these preparations as a root-end filling material. All teeth were then placed in a humidor for an additional 48 h. The coronal and lateral aspects of these teeth were also coated with two coats of nail varnish and allowed to dry. The root-ends were then submerged in India ink for 48 h. The apical 3 mm of the positive and negative control teeth were resected in a manner similar to that of Groups 1 and 2. Root end cavities were prepared in both control groups with a 330 carbonsteel bur to a depth of 3 mm. The positive control group received warm condensed gutta percha with no sealer retrograde as a rootend filling. The negative control group received MTA retrograde as a root-end filling. Both control groups were then placed in a humidor for 48 h. Sticky was placed over the root-end filling in the negative control group and the coronal and lateral aspects of teeth in both the positive and negative control groups were coated with Placement of a root-end filling is often the final step of tooth preparation during periradicular surgery. According to Pitt Ford (1), a good root-end filling material should be biocompatible, antibacterial, insoluble, dimensionally stable, easy to handle, radiopaque, nondiscoloring to the surrounding tissues, and should provide a tight seal. Mineral Trioxide Aggregate (MTA) fulfills most of these recommendations and is currently being extensively used as a rootend filling material (2). Although the mechanism of healing adjacent to MTA is not yet understood, the formation of cementum against MTA may be because of its superior marginal adaptation (3, 4, 5). Under some circumstances, MTA may be used to obturate the entire root canal. In these instances, if periradicular surgery is subsequently required, the clinician may elect to resect the rootend, exposing previously set MTA, and not place new MTA in the root-end as filling. 573 574 Andelin et al. Journal of Endodontics two coats of nail varnish similar to Groups 1 and 2 and allowed to dry. The root-ends were then submerged in India ink for 48 h. Following exposure to dye, the roots of all groups were then grooved on the buccal and lingual surfaces and split into two sections. The amount of dye penetration was examined with a surgical microscope at 16 ⫻ magnification (Global Surgical Corp., St. Louis, MO, U.S.A.). RESULTS All the canals in the positive control group demonstrated leakage throughout the entire root lengths. The root canals in the negative control group did not display any leakage. There was no discernible leakage in teeth with resected MTA or in those with MTA placed as a retrograde root-end filling material. No significant difference in leakage was found between Group 1 and Group 2. DISCUSSION When non-surgical root canal treatment is unsuccessful, surgical root canal treatment is often performed. Following root-end resection and ultrasonic root-end preparation, a root-end filling material is usually used to seal the root. MTA is currently used as a root-end filling material (2). From an orthograde direction, MTA may also be placed either as an apical plug or to obturate an entire canal. In these instances, if periradicular surgery is subsequently required, the clinician may elect to resect the root-end containing set MTA and not place new MTA retrograde as a root-end filling material. The purpose of this study was to evaluate if the resection of MTA-placed orthograde as a root-canal-filling material would disturb the apical seal. We found no significant difference between the apical seal of resected MTA-placed orthograde and the apical seal of MTA-placed retrograde as a root-end filling. These findings corroborate with previous findings that show that MTA seals significantly better than amalgam, Super EBA, and IRM (3, 4, 6). The healing properties of MTA have been compared to amalgam when used either as a root-end filling material or in the repair of experimentally induced furcal perforations (7). It has been shown that MTA produces significantly less inflammation and more fibrous capsule formation when compared to amalgam. In addition, MTA has the unique ability to induce cementum formation directly adjacent to its surface (1, 7, 8). The reason for the cementum formation against MTA may be because of its superior marginal seal (3, 4) or other factors (9). Apaydin et al. (10) compared the healing and extent of cementum deposition on resected set MTA with fresh MTA as a root-end filling material in dogs. The frequency of cementum formation with retrograde MTA was higher when compared with that of resected set MTA. When comparing the amount of cementum formation in the two groups, they found no significant difference between the two groups. Based on their results, it appears that fresh MTA is more inductive than resected set MTA. However, the presence of resected set MTA adjacent to periradicular tissues did not prevent regeneration of these tissues in a majority of cases. Based on the results of this study it appears that the sealing ability of MTA placed in an orthograde manner and allowed to set is not affected by root-end resection. This may prove to be beneficial in cases where difficult access and isolation might prohibit placement of MTA as a root-end filling material. Drs. Andelin, Browning, Hsu, and Roland are Post-graduate residents affiliated with the Department of Endodontics, Loma Linda University School of Dentistry, Loma Linda, CA, U.S.A. Dr. Torabinejad is a Professor of Endodontics and the Director of Graduate Endodontics, Loma Linda University School of Dentistry, Loma Linda, CA, U.S.A. Address requests for reprints to Dr. Wallis E. Andelin, Department of Endodontics, Loma Linda University School of Dentistry, Loma Linda, CA 92350, U.S.A. References 1. Ford TR, Torabinejad M, McKendry DJ, Hong CU, Kariyawasam SP. Use of mineral trioxide aggregate for repair of furcal perforations. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1995;79:756 – 63. 2. Torabinejad M, Chivian N. Clinical applications of mineral trioxide aggregate. J Endodon 1999;25:197–205. 3. Torabinejad M, Watson TF, Pitt Ford TR. Sealing ability of a mineral trioxide aggregate when used as a root end filling material. J Endodon 1993; 19:591–5. 4. Torabinejad M, Higa RK, McKendry DJ, Pitt Ford TR. Dye leakage of four root end filling materials: Effects of blood contamination. J Endodon 1994;20:159 – 63. 5. Torabinejad M, Smith PW, Kettering JD, Pitt Ford TR. Comparative investigation of marginal adaptation of mineral trioxide aggregate and other commonly used root-end filling materials. J Endodon 1995;21:295–9. 6. Torabinejad M, Rastegar AF, Kettering JD, Pitt Ford TR. Bacterial leakage of mineral trioxide aggregate as a root-end filling material. J Endodon 1995;21:109 –12. 7. Torabinejad M, Hong CU, Lee SJ, Monsef M, Pitt Ford TR. Investigation of mineral trioxide aggregate for root-end filling in dogs. J Endodon 1995;21: 603– 8. 8. Torabinejad M, Pitt Ford TR, McKendry DJ, Abedi HR, Miller DA, Kariyawasam SP. Histologic assessment of mineral trioxide aggregate as a root-end filling in monkeys. J Endodon 1997;23:225– 8. 9. Koh ET, Torabinejad M, Pitt Ford TR, Brady K, and McDonald F. Mineral trioxide aggregate stimulates a biological response in human osteoblasts. J Biomed Mater Res 1997;37:432–9. 10. Apaydin ES, Shabahang S, Torabinejad M. Hard tissue healing following fresh or set MTA as root end filling material. J Endodon 2002;28:252.