Introduction: This study aimed to evaluate and compare the apical sealing ability of different irrigation regimens (NaOCl, CHX, NS, and MTAD) .

Methods: Seventy intact extracted single-rooted human teeth were selected. The roots were resected at 3 mm short of the apical foramen after access preparation. The canals were prepared with profile. This rotary file moved forward into the apical foramen so that the D16 section of the file passed the foramen of the resected part of the root. The teeth were randomly divided into 4 study groups. After placing them in humid sponge, the canals were irrigated with study irrigators for 5 minutes. The canals were dried and 5mm MTA was placed into the apex. After 24 hours, the teeth were placed indian ink solution. The teeth were cleaned and the microleakage was tested using stereomicroscope.

Results: The results showed no significant difference between the group of 2% Chlorhexidine and the other groups. 0.5% Naocl group showed significantly less leakage than MTAD and normal saline groups.

 Conclusions: The results of this study suggested that 0.5% NaOCl provided the best final irrigation before the apical placement of MTA.