Combined Endodontic Retreatment and Intentional Replantation for External Cervical Resorption: A Four-Year Follow-Up Case Report

Background and Clinical Significance: External cervical resorption (ECR) is an insidious form of root resorption that frequently progresses undetected until an advanced stage, particularly when the lesion extends apical to the alveolar crest or involves a substantial proportion of the root circumference, precluding adequate visualization and debridement via conventional intraoral approaches. Case Presentation: This report describes the management of a 30-year-old male who presented with an acute apical abscess associated with a mandibular second molar with inadequate previous root canal treatment, in conjunction with an extensive distal cervical resorption defect and a large periapical radiolucency. Due to lack of availability of a CBCT machine at the time, no preoperative CBCT was obtained; diagnosis and treatment planning were based on clinical examination and periapical radiography. Given the anatomical inaccessibility of the resorptive lesion and the concurrent persistent periapical pathology, treatment consisted of nonsurgical root canal retreatment followed by intentional replantation to permit extraoral access and repair. The tooth was replanted after an extraoral period of less than 15 min and stabilized with a flexible splint. The patient was reviewed at 2 weeks and was then lost to routine follow-up until a 4-year reassessment. At that time, the tooth was functional and asymptomatic, with complete radiographic resolution of the previous periapical radiolucency and no clinically or radiographically evident signs of progressive root resorption or ankylosis. Conclusions: This case documents a favorable four-year outcome following intentional replantation combined with endodontic retreatment and bioceramic repair in a multi-rooted tooth with extensive, conventionally inaccessible ECR.