A 20-Year Post-traumatic Presentation of a Horizontal Root Fracture Accompanied by Bone Resorption and Sinus Tract: A Case Report.

Horizontal root fractures present unique diagnostic and treatment challenges, particularly in cases with delayed presentation. This report describes the management of a 20‑year‑old untreated horizontal root fracture of the maxillary left central incisor, complicated by the presence of a persistent sinus tract. A 56‑year‑old male patient was referred due to mild anterior maxillary pain accompanied by purulent discharge. Clinical examination revealed Grade II mobility and tenderness upon percussion of tooth 21. Fistulogram traced the sinus tract to a displaced apical fragment of tooth 21. Endodontic treatment was conducted on the coronal fragment under magnification, including canal shaping, calcium hydroxide dressing, and final obturation with Biodentine (Septodont, Saint-Maur-des-Fosses, France). The persistence of the sinus tract during follow‑up indicated necrosis of the apical fragment. Surgical removal was performed using a papilla‑based flap technique under a dental operating microscope, ensuring the preservation of the surrounding periodontal and osseous structures. Healing progressed uneventfully, with complete resolution of the sinus tract and stability of the coronal fragment confirmed at 3‑, 6‑, and 12‑month post-treatment. This case highlights the potential for late‑onset pulp necrosis occurring decades after trauma in horizontal root fractures and emphasizes the importance of individualized management strategies. Selective endodontic treatment of the coronal fragment, in conjunction with the surgical removal of a necrotic apical fragment, may represent a conservative and effective approach that preserves tooth function and obviates complete extraction in chronic presentations with persistent pathology. Early diagnosis and periodic monitoring are critical for preventing such long‑term complications.