Spontaneous Bone Regeneration ("Phoenix Jaw" Phenomenon) Following Segmental Mandibulectomy for Stage 3 Medication-Related Osteonecrosis of the Jaw: A Case Report.

Segmental mandibulectomy is a valid treatment for advanced medication-related osteonecrosis of the jaw (MRONJ), but subsequent reconstruction is challenging. Spontaneous bone regeneration (SBR) following resection is exceedingly rare, particularly in the elderly. We present the case of a 63-year-old woman with stage 3 MRONJ who underwent a 60 mm segmental mandibulectomy. The defect was reconstructed with a titanium plate, with meticulous preservation of the periosteum. Over a three-year follow-up period, serial imaging demonstrated progressive and substantial bone regeneration along the plate, resulting in a robust, continuous mandibular segment without any bone grafting. This case highlights that SBR, a phenomenon metaphorically termed the "Phoenix jaw," can occur even in older patients with advanced MRONJ, challenging conventional expectations regarding bone regeneration in this patient population.