Evaluation of Apical Microleakage in Open Apex Teeth Using MTA Apical Plug in Different Sessions.

Aim. To compare microleakage of apexification using MTA in one or two sessions. Materials and Methods. 88 single rooted teeth were prepared and divided into two groups then received MTA apical plug. In the first group, the teeth were immersed in normal saline for 24 hours and then backfilled with guttapercha and AH26 sealer. In the second group, the teeth were obturated immediately after receiving apical plug. Four positive and four negative controls were selected. All specimens were placed in 1% methylene blue and decalcified in 5% nitric acid and finally were placed in methyl salicylate until getting transparent. All teeth were visualized for assessment of dye penetration under stereo dissecting microscope. Results. 36 and 35 teeth showed dye leakage in the first and second groups. Dye penetration into the entire canal length was confirmed in the positive control group, and in the negative control group no dye penetration was seen. Mean dye penetration in the first and second group was 5813 and 9152  μ m. t-test revealed a significant difference between dye penetrations of two groups (P < 0.05). Conclusion. MTA requires adequate time for setting in the presence of the moisture, and final obturation should be delayed until final setting of MTA.