Introduction: Dens invaginatus is a malformation of the tooth during embryonic development that presents in several morphological types. This article reports a case of a type II dens invaginatus with an extensive periradicular lesion that was treated successfully. Methods: Three-dimensional imaging, cone beam computed tomography (CBCT) was used to identify the morphology of dens invaginatus and to help devise a treatment plan. Nonsurgical and surgical endodontic treatments were performed to achieve a favourable outcome. Conclusions: Understanding both the configuration of the internal root canal and irregularities of the external root using CBCT can ensure predictable and successful results, as in this case. The 2-year follow-up showed complete healing of the periapical pathosis. Schlagwörter: cone beam computed tomography (CBCT), dens in dente, dens invaginatus, endodontic surgery, endodontic treatment