Since there are not many references in literature about the action of diode laser 940nm on the dentin and root smear layer, the aim of this study is to evaluate and compare, through SEM analysis, the efficiency of the Sodium hypochlorite 2% (CERKAMED) - EDTA 17% (CERKAMED) combination, operated in the middle and apical third of the root, by conventional syringe needle EndoEze and diode laser 940nm treatment. The study was performed on 40 single-root teeth, which were divided into two groups: group A consisting of 20 teeth, for which irrigation was performed only with the syringe and a top open side needle EndoEze Irrigator, resulting in a turbulence moving upward which efficiently irrigates the root canal and prevents periapical water solution; and group B consisting of 20 teeth, which benefited from irrigation associated with diode laser 940nm treatment. In the middle third and apical third smear layer removal was more effectively achieved when teeth benefited from irrigation associated with the laser diode treatment. In Endodontics, Diode laser is a good decontamination system, with biostimulation effect, which is important in healing the periapicale area. Significantly better results were obtained using 940nm laser diode associated with successive irrigation with 2% NaOCl and 17% EDTA, as compared to the conventional technique performed by syringe and lavage needle EndoEze Irrigator (Ultradent).