Dens invaginatus type 3 is an anomaly characterized by an infolding of enamel and dentin that can extend up to the root apex and might present difficulties with respect to its diagnosis and treatment because of canal morphology. This article describes an unusual case of the maxillary canine having a type 3 dens invaginatus, necrotic pulp, and an associated large periradicular lesion treated by conventional root canal therapy. After gaining access to the pulp chamber, the primary canal and the invagination were localized, negotiated, enlarged, and filled with calcium hydroxide. Three weeks later the canal and the invagination were obturated with gutta-percha and restored. At 24-month recall satisfactory bone healing had occurred.