Management of persistent periapical lesion associated with a separated instrument and external apical root resorption using combined nonsurgical and surgical endodontic therapy: A 12-month follow-up case report

Persistent apical pathosis involving multiple teeth may require different treatment strategies depending on the underlying biological and anatomical factors. This case report describes the tooth-specific management of four maxillary anterior teeth in a 30-year-old female with persistent apical pathosis and a recurrent sinus tract following failed endodontic retreatment. Cone-beam computed tomography (CBCT) revealed a separated instrument extending beyond the apex, external apical root resorption, extruded root canal filling material, and labial cortical plate perforation involving teeth #11 and #12, whereas teeth #21 and #22 exhibited uncomplicated periapical lesions. Based on tooth-specific findings, nonsurgical root canal treatment was performed for #21 and #22, while #11 and #12 underwent endodontic microsurgery with instrument retrieval, root-end resection, ultrasonic retro-preparation, mineral trioxide aggregate root-end filling, and bone grafting. Twelve-month follow-up demonstrated symptom resolution, soft-tissue healing, and progressive periapical bone regeneration. This case emphasizes individualized, CBCT-guided treatment planning for managing complex persistent apical pathosis while preserving the natural dentition.