Despite all modern resources in endodontic treatment, in some cases conventional treatment is not enough to solve cases of root canal infections associated with cysts or granulomas. A patient came to the clinic complaining of pus discharge in the gingival region. Clinical examination revealed the presence of a fistula in the right upper anterior region, darkening of the crown of tooth 22, and negative pulp tests on teeth 21 and 22. Radiographic and tomographic examination revealed extensive periapical lesion related to the apices of teeth 21 and 22. Due to the staining of the crown of tooth 21, we opted for endodontic treatment of tooth 22 only, and medication with calcium hydroxide. In the second session, there was no fistula remission and tooth 21 responded positively to the thermal test. In the third session, without remission of the fistula, we opted for medication with Bio C Temp (Angelus) also without success, verified 1 month later. It was then chosen the filling and subsequent paraendodontic surgery by apicectomy, which finally showed positive results in relation to clinical signs after 1 week and radiographic, observed after 6 months. Case performed by students Lorrane Souza and Amanda Ribeiro of the specialization in endodontics of HPG Brasília.