New Immunological Insights into Bisphosphonate-Related Osteonecrosis of the Jaw: A Multidimensional Reappraisal from Molecular Switches to Clinical Phenotypes

Bisphosphonates (BPs) are cornerstone therapeutic agents for the management of metabolic bone disorders and skeletal complications associated with malignant tumors. However, their long-term administration is accompanied by the risk of developing bisphosphonate-related osteonecrosis of the jaw (BRONJ). In recent years, the pathogenesis of BRONJ has remained a major focus at the intersection of osteoimmunology and oral medicine. This review systematically summarizes the latest advances in the understanding of BRONJ pathogenesis, including the direct disruption of osteoclast differentiation and bone remodeling coupling by bisphosphonates, the systemic reprogramming of immune cell subsets and inflammatory signaling pathways, the multifaceted suppression of angiogenesis and the endothelial–stromal–immune axis, and the toxic impairment of oral soft tissue repair capacity. Building upon these mechanistic insights, we further discuss the modifying and synergistic effects of local oral risk factors, microbial dysbiosis, systemic comorbidities, and genetic susceptibility on the initiation and progression of BRONJ. Furthermore, emerging therapeutic strategies targeting these pathogenic mechanisms are highlighted, including restoration of small GTPase prenylation through modulation of metabolic pathways, reconstruction of T-cell subset homeostasis via immunomodulatory approaches, enhancement of local vascularization through pro-angiogenic interventions, and preservation of soft tissue barrier integrity. Collectively, this review provides a comprehensive and multidimensional overview of the pathological landscape of BRONJ and offers a theoretical framework for clinical risk stratification and the development of personalized prevention and treatment strategies.