Objectives: To identify clinical and tomographic prognostic factors for conservative and surgical treatment of medication-related osteonecrosis of the jaws (MRONJ). Methods: A retrospective search identified patients treated with antiresorptive drugs (ARDs), diagnosed with Stage 1, 2 or 3 MRONJ, and having CBCT scans previous to conservative or surgical treatment. Following data collection, imaging assessment of the following parameters on each MRONJ site was performed: involvement of teeth and/or implants, presence of osteosclerosis, osteolysis, sequestrum formation, periosteal reaction, and pathological fractures. For statistical analysis, patients and lesions were divided into conservative and surgical treatment. Comparisons were made between successful and unsuccessful outcomes. Significance was set at p ≤ 0.05. Results: 115 ARD-treated patients who developed 143 osteonecrosis lesions were selected. 40 patients and 58 lesions received conservative treatment, of which 14 patients (35%) and 25 lesions (43%) healed. Additionally, 75 patients and 85 lesions underwent surgery, with 48 patients (64%) and 55 lesions (65%) that healed. Clinical and tomographic risk factors for conservative treatment were MRONJ staging, tooth involvement, extensive osteosclerosis, and deep sequestrum formation (p < 0.05). Complementarily, poor prognostic indicators for surgical therapy were a short bisphosphonate (BP) holiday, MRONJ staging, absence of sequestrum formation, and presence of periosteal reaction (p < 0.05). Conclusions: Lesions at Stage 3 MRONJ, with tooth involvement, or sequestrum formation showed poor outcomes when conservative treatment is chosen. Alternatively, surgical treatment is most effective when BPs are discontinued, in Stage 1 lesions, in the presence of sequestrum formation, and absence of periosteal reaction.