The article discusses the issue of interventional endodontics and root canal retreatment (re-endo), emphasizing the importance of accurate diagnosis, proper canal preparation techniques, and hermetic obturation of the root canal system for long-term treatment success. The paper presents a case report of a 60-year-old patient who reported to the dental office due to pain in tooth 43, which had previously undergone endodontic treatment at another clinic. Clinical examination revealed partial loss of the restoration in tooth 43 as well as progressive swelling of the right cheek. A periapical radiograph was taken, showing an underfilled canal and partial loss of the mesial restoration, along with a periapical lesion. The article discusses the issue of interventional endodontics and the challenges associated with root canal retreatment.

Key words: repeated root canal treatment, complications, broken tool.