Spontaneous Bone Regeneration After Segmental Resection of Mandible for MRONJ: An Unexpected Favorable Outcome

Spontaneous bone regeneration (SBR) following segmental mandibulectomy for medication-related osteonecrosis of the jaw (MRONJ) is a favorable but unpredictable outcome. Its predictive factors remain poorly understood. This study aimed to identify clinical and demographic predictors for the occurrence and timing of SBR in MRONJ patients. This retrospective study analyzed 16 patients who underwent segmental mandibulectomy for MRONJ. The primary outcome was the presence of SBR. Multivariable logistic regression was used to identify independent predictors of SBR occurrence. A recursive partitioning analysis identified an optimal age threshold, which was used in a Kaplan-Meier analysis to assess the timing of SBR onset. SBR occurred in 9 of 16 patients. Patients with SBR were significantly younger than those without (mean age: 65.2 versus 79.6 years; P=0.029). Age was the sole independent predictor in the multivariable analysis (P=0.02). The Kaplan-Meier analysis demonstrated a significantly earlier onset of SBR in patients younger than 76 years (log-rank P=0.0074). Younger age is a strong, independent predictor for both the occurrence and earlier initiation of SBR following segmental mandibulectomy for MRONJ. While this finding can inform prognostic discussions, SBR should be regarded as a favorable biological event rather than a dependable reconstructive strategy.