This case report presents the surgical endodontic treatment of an Oehlers Class II invaginated immature tooth. In this case, communication between the invagination and the pulp caused pulp necrosis, periapical inflammation, and cessation of root formation. The initial treatment goal was to achieve apexification and then fill both the root canal and the canal of the invagination. After a 6-month treatment with calcium hydroxide dressings, there was no healing radiographically and no sign of a hard tissue barrier in the apex. Periapical surgery with the placement of mineral trioxide aggregate (MTA) root-end filling was deemed successful at the 1-year recall. To treat dens invaginatus, both conventional and surgical endodontic treatment techniques should be considered. In dens invaginatus, conventional endodontic treatment modalities may be unsuccessful because of inadequate debridement and disinfection; however, subsequent periapical surgery and retrofilling with MTA may promote healing.