Nonsurgical Retreatment of a Mandibular Molar with Internal Resorption and a Separated Endodontic Instrument Deep within the Body of the Mandible.

Fracture of an endodontic instrument during an endodontic procedure is a common complication, but displacement of the separated instrument either inside or by the side of the inferior alveolar canal is very rare. This case report presents nonsurgical retreatment of a symptomatic, previously endodontically treated mandibular left first molar tooth with internal root resorption. The unique feature of this case report is the presence of a separated endodontic instrument entirely beyond the root apex and located deep within the body of the mandible. Under rubber dam isolation, access cavity preparation was carried out, and previous root canal obturating materials were removed. Intracanal dressing with calcium hydroxide was placed for two visits, and in the subsequent visit, the root canals were obturated. The periapical lesion healed at 24 months of follow-up. The separated endodontic instrument was monitored regularly through clinical and radiographic examinations, and the patient remained asymptomatic during this period.