Volumetric analysis of spontaneous bone formation after segmental mandibulectomy in patients with MRONJ.

Objective: The purpose of this study was to quantify the spontaneous new bone formation and bony bridge formation by 3-dimensional analysis of cone-beam computed tomography (CBCT) after segmental mandibulectomy reconstruction using an R-plate without any graft material in patients with medication-related osteonecrosis of the jaw (MRONJ).
Study Design: 15 MRONJ patients (13 females and 2 males) were selected based on the inclusion criteria. Data on new bone formation, bony bridge formation, R-plate fracture, patient age, and type and duration of medication were collected. Panoramic and CBCT scans were obtained at 1 day, 6, 12, and 24 months postoperatively. CBCT images of each period were transferred to a personal computer using MIMICS 21.0 for volumetric analysis. After quantifying the volume of new bone formation, we calculated the percentage of the volume of new bone to the segmentally resected necrotic bone volume (%NB).
Results: All patients showed spontaneous new bone formation with the average of 20.69% within a year and 28.52% within 2 years, and 80.0% showed bony bridge formation within a year.
Conclusions: The R-plate reconstruction in patients with MRONJ showed significant amount of spontaneous new bone formation within 2 years after segmental mandibulectomy.
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