Methods: 24 single-rooted human teeth were used in this study. Collected teeth were stored in physiologic saline before the procedures. The root canals were enlarged with K-files to apical size #60. Canals were irrigated with 2 ml of 2.5% NaOCl after each instrument.
External defects of 3 mm in diameter and 1 mm in depth were created in the middle one-third of the root surfaces to expose dentinal tubules. And then, root canals and external defects were irrigated with 17% EDTA to remove the smear layer and rinsed with unbuffered isotonic saline solution. Canals and root surfaces were dried with paper points.
MTA powder was mixed with saline in a 3:1 ratio and placed into canal using a lentulo spiral until the material reached the canal orifice. Different size pluggers were used to condense MTA to obtain better MTA adaptation to canal walls. The coronal access was sealed with IRM. And root surfaces were sealed with two coats of nail polish except the created perforation site and allowed to dry at room temperature. The teeth were immersed in a bottles containing 10 ml saline. The teeth were kept at 37 0C 100% humidity incubated throughout the observation period. Ca2+ concentration released from the defect in the surrounding media were measured by an Electrolyte Analyzer at 1, 3, 7 ,14,and 28 days. The results were statistically analyzed. Results: Ca2+ concentration showed an increase by time which was statistically significant (p<0.05). However measured pH values did not exhibit significant differences. Conclusion: In the light of this results, MTA is useful root canal filling material in treatment of small lateral root perforations.