ABSTRACT
Dens invaginatus is a dental anomaly that may show many different complex anatomical forms. The complexity of the internal anatomy of the root canal may create difficulties and challenges for treatment completion of the root canal. A 10-year-old girl was referred by her dentist suffering from pain and a persistent infection arising from the maxillary left lateral incisor. After clinical examination, the case was classified as Oehler's type II due to invagination extending through the root canal with no communication with the periodontal tissue. The main canal contained a central cylindrical mass of hard tissue. Owing to a limitation in access to the canal system and the cleaning and sealing of canal spaces, a modification of the internal anatomy of the canal system was achieved under the operating microscope. The conventional chemical and mechanical preparation with sodium hypochlorite combined with intracanal calcium hydroxide was done. The root canal was obturated with MTA. In this case, the conventional root canal treatment and the modification of the internal anatomy promoted the regression of the lesion noted at 2-year follow up