Objectives:The aim of the present study was to evaluate the sealing ability of experimental nano sealers (nano calcium hydroxide and nano bioactive glass) and to compare it with the commercial AH plus sealer using a dye penetration method. Materials and methods:Sixty single-rooted mandibular premolars were selected. The coronal portion of each tooth was removed to standardize root length at 16 mm and the root canals were prepared with NiTi rotary files (ProTaper Next) up to X4 (40/0.06). Teeth were randomly assigned and divided according to the sealer used for obturation into three groups of 20 each. Group I: AH plus, Group 2: Nano calcium hydroxide and Group 3: Nano-bioactive glass. All root canals were obturated using single cone gutta-percha(#40/.06) and one of the tested sealers. Root canal sealing was assessed by a dye penetration test. The data were statistically analyzed by ANOVA test followed by post hoc analysis (P < 0.05).Results: Significant improvement shown by the presented study suggests that nano calcium hydroxide sealer showed significantly less dye leakage than nano bioactive glass sealers and Ah plus sealer. Conclusion:The results of this study showed that the synthesized nano-powder sealers are suitable for use in root canal therapy to prevent leakage. The root canal can be sealed better by using smaller nano-powder particle sizes. In addition, the two groups exhibited significant differences in leakage in comparison with commonly used AH plus sealer.