Aim of this study: To evaluate the effect of different irrigation solutions on the removal of smear layer from root canals, the effect of active irrigation on smear layer removal and resin penetration into dentinal tubules. Materials and Methods: Ninety six extracted straight single-rooted be divided equally into three groups GROU P A :( n=32) (control group) irrigated with 2.5% NaOCl, GROUP B: irrigated with 2.5%NaOCl and17% EDTA, GROUP C: irrigated of 2.5%NaOCl and 10% citric acid as a final irrigant. Each group will be subdivided equally into two subgroups (16 teeth each). The first subgroup with no activated during irrigation. The second will be activated after flushing the final irrigant with EndoActivator for 1 minute. The teeth will be sealed with AHplus as resin based-sealer. Before and after obturtion, the teeth from each group were sectioned and prepared for examination using Scan Electron Microscope. Results: SEM photomicrographs showed better removal of smear layer and dentinal tubules more opened with Endoactivator system. EndoActivator system produced a significant higher depth of penetration values for all the different irrigating solution and removing smear layer. Conclusion: EndoActivator showed superior removal of smear layer. In addition sonic irrigation enhanced its physical and chemical properties in penetrating of AH Plus sealer into dentinal tubules.