Dens invaginatus is an anomaly of the tooth formation, its root canal treatment is a real challenge due to the severe complex of root anatomy. This paper reports the nonsurgical endodontic management of three cases of maxillary lateral incisor with type I, II and III dens invaginatus, necrotic pulp and periapical lesion. Cone Beam Computed Tomography (CBCT) was used to get a three-dimensional observation of this area. The use of dental operating microscope and ultrasonic tips helped us to eliminate the invagination safely.