Aim: This study evaluated and compared the sealing ability and adaptation of two different based root canal sealers; iRoot SP (Calcium Silicate-based) and ADSEAL (resin-based) after removal of the smear layer when used in single cone or lateral condensation obturation techniques. Methodology: Eighty single rooted human teeth were decoronated to obtain 12 mm root segments. The samples were randomly divided into two main groups (40 roots each) according to the irrigating material used during instrumentation either 5.25% NaOCl or 2% CHX. Final flush with 17% EDTA was done for both main groups. Each main group was further subdivided into two subgroups (20 roots each) according to the technique of obturation employed either single cone or lateral condensation technique. Each subgroup was further subdivided into two subdivisions (10 roots each) according to the sealer used. Half of the examined samples were subjected to dye extraction method for leakage evaluation and the other were longitudinally sectioned to examine the adaptation of the tested sealers using the environmental scanning electron microscope (ESEM) examination. Results: Statistical analysis of the data revealed that the irrigation using 5.25% NaOCl and 2% CHX did not significantly affect the sealing ability of the iRoot SP and ADSEAL sealers (p value>0.05). However, there was a general trend that 5.25% NaOCl irrigation was better than 2% CHX irrigation. Also, technique of obturation whether single cone or lateral condensation did not significantly affect the sealing ability of the iRoot SP and ADSEAL sealers (p value>0.05). However, the results of single cone obturation were better than lateral condensation obturation. Apical sealing ability of iRoot SP sealer was better than ADSEAL sealer with significant difference between the two sealers (p value≤0.05), there was no statistically significant difference between iRoot SP and negative control group (p value>0.05).ESEM revealed the best adaptation with iRoot SP sealer using single cone obturation technique, While in case of lateral condensation technique with ADSEAL, gaps were detected along sealer and both dentin and gutta percha interface. Conclusions: iRoot SP sealer revealed better sealing ability than ADSEAL sealer. Single cone technique can be used safely with iRoot SP sealer as it revealed the best results as regards its sealing ability and adaptation.