Introduction
Medication‐related osteonecrosis of the jaw (MRONJ) occurs even after teeth with poor prognosis had been preventively extracted and medication had been initiated. In this nested case–control study, we focused on tooth extraction before bone resorption inhibitor administration for the treatment of malignant tumors.
Materials and Methods
A total of 180 teeth of 58 patients who were treated with zoledronic acid and/or denosumab from April 2012 to December 2016 at our hospital or partner institutions were included in this multicenter study. All participants underwent tooth extraction within 1 year before initiating therapy and were followed up for at least 1 year or at most 3 years after initiating bone resorption inhibitor administration. We evaluated the systemic and local risk factors: sex, age, cancer type, overweightness/obesity, anemia, undernutrition, diabetes, smoking, concomitant drugs, tooth extraction site, use of antibacterial drugs, wound closure, and waiting period between tooth extraction and medication.
Results
MRONJ occurred in 18 teeth of 10 patients and not in 162 teeth of 48 patients. Based on the Cox proportional hazards model, concomitant administration of angiogenesis inhibitors, mandibular molar, periapical radiolucency, and osteosclerosis of the surrounding areas were considered essential risk factors for MRONJ.
Conclusions
Chronic inflammation of the bone surrounding extracted teeth may be an essential risk factor for MRONJ when preventive tooth extraction is performed before the administration of bone resorption inhibitors for patients with malignant tumors.