A Multi-Center Observation Study on Medication-Related Osteonecrosis of the Jaw (MRONJ) in Patients with Osteoporosis, and Other Non-Malignant Bone Diseases, in Northwestern Italy over 16 Years.

Objectives: To assess the number of new cases of Medication-Related Osteonecrosis of the Jaw (MRONJ) among patients with osteoporosis and other non-malignant bone diseases in Northwestern Italy between 2007 and 2022. Methods: MRONJ cases were collected from referral centers in a population of 4.5 million. We analysed the number of new MRONJ cases per year, type of disease, administered drugs, duration of therapy (when available), and onset time of disease. Results: We analysed 198 cases (out of 1071 total MRONJ cases); diseases included osteoporosis (87%), rheumatoid arthritis (5%), their association (4%), Paget's disease, and other various diseases (4%). Patients received bisphosphonates alone (74%), or denosumab alone (6%), or a sequence of different drugs (20%). The number of new cases increased over five years from 2 (2003-2007) to 51 (2008-2012), 65 (2013-2017), and 79 (2018-2022), and the percentage increased from 1% to 14%, 20%, and 29% of the total cases. Conclusions: The number of new MRONJ cases per year among patients with non-malignant diseases is rapidly increasing all around the world, though underestimation cannot be excluded. In this study, we describe epidemiological and clinical characteristics of patients, and the drug most frequently involved in MRONJ cases in our region over a long period, allowing a comprehensive view of the progression of the disease. Greater collaboration among specialists is needed for correct and early diagnosis to improve measures potentially reducing disease incidence and to limit quality of life deterioration in patients with osteoporosis and other non-malignant diseases.