The paper presents a case report of a 46-year-old patient who reported to the clinic due to toothache of tooth 36, previously treated endodontically by another dentist. The patient's physical examination revealed a fistula and a prolonged reaction to percussion. The X-ray showed an underfilled distal canal, a lack of filling and broken instruments left in the mesial canals. The paper presents the problem of root canal retreatment and removal of instruments left inside the root canal system of the tooth.

Key words: root canal retreatment, complications, broken instruments.