The objective of this study is to discuss and analyze whether extrusion of endodontic material constitutes avoidable intercurrence, discussing the clinical, ethical and legal implications. Patient LSR, 31 years old, female, attended a dental consultation complaining of pain in the second left maxillary premolar (tooth 25). Radiographically, a single root canal and thickening of the periodontal ligament associated with extravasation of 8 mm of gutta percha to the maxillary sinus were observed. The first endodontic session aimed to performing the desobturation, root canal preparation and intracanal medication placement. The root canal obturation was performed in the second session. Was carried out an apical surgery that removed 2 mm from the root apex and also performed the covered with a collagen membrane. A 22 months follow-up revealed a tooth function, absence of painful symptomatology or infection, and radiographically normal periodontal ligament and bone neoformation. The second single-root premolar is the type of premolar with less distance with the floor of the maxillary sinus. In this case, the extrusion of the obturator material occurred due to the superinstrumentation of the root canal associated with the proximity of the root with the membrane of the maxillary sinus. From the ethical and legal point of view, the patient has the right to be informed about any intercurrences that may arise during or after the treatment, and the informed consent form is essencial. This document will allow the patient to make a decision about performing an endodontic treatment in which the risk of an accident or complication is imminent or that treatment failure is already expected. It is important that professionals make appropriate diagnosis and treatment plan for each case, since this conduct may avoid clinical intercurrences. In addition, if the intercurrences occur, the patient should be advised of how to proceed.