Anatomical and Systemic Risk Factors for Recurrence in Medication-Related Osteonecrosis of the Jaw (MRONJ): A Retrospective Study of 812 Patients

Background/Objectives: Medication-related osteonecrosis of the jaw (MRONJ) is a severe complication of antiresorptive and antiangiogenic therapies, and identifying specific risk factors for recurrence remains a significant clinical challenge. This study aimed to evaluate the clinical characteristics and independent risk factors for recurrence in a large-scale cohort of MRONJ patients. Methods: This single-center retrospective study analyzed 812 patients diagnosed with MRONJ according to the 2022 AAOMS criteria at Chosun University Dental Hospital between 2020 and 2024. Demographic, clinical, radiographic, and medication-related variables were collected. Univariate and multivariate logistic regression analyses were performed to identify independent risk factors associated with recurrence. Results: The majority of patients were female (89.9%), with a mean age of 72.9 years, and mandibular involvement was most frequent (70.8%). Tooth extraction was the most common local precipitating factor (47.0%). The overall recurrence rate was 10.1%. Multivariate analysis identified bilateral jaw involvement (OR = 4.555, p = 0.006), mandibular ramus involvement (OR = 8.222, p = 0.008), and systemic liver disease (OR = 3.703, p = 0.037) as significant independent risk factors. Conversely, routes of prior antiresorptive medication administration involving intravenous-only or combined oral/intravenous therapy, as well as hyperlipidemia and a history of dental implant surgery, were associated with lower recurrence rates. Conclusions: Anatomical complexity and systemic health status are critical predictors of MRONJ recurrence. Patients presenting with bilateral or mandibular ramus involvement, or with compromised liver function, require more aggressive surgical debridement and individualized treatment planning to reduce the risk of recurrence. Given the small affected subgroups, the effect sizes for mandibular ramus involvement and liver disease should be interpreted with caution.