Bisphosphonates and oral cavity avascular bone necrosis: A review of twelve cases

Background: Intravenous bisphosphonates are the current standard of care for the treatment of hypercalcemia of malignancy and for the prevention of skeletal complications associated with bone metastases. Recently, retrospective case studies have reported an association between long-term bisphosphonate therapy and osteonecrosis of the jaws. Patients and Methods: The data for twelve patients, referred to either an oral and maxillofacial surgeon or to an oral medicine specialist for the management of clinically apparent chronic oral osteonecrosis of unknown etiology. were reviewed. All had received cancer-related therapy simultaneously with bisphosphonate management. Results: The typical presenting symptoms were pain and exposed bone at the site of a previous tooth extraction. In most patients, the lesions initially occurred after dental extraction or other odonto-stomatological procedures, while five had a spontaneous event. Biopsy of the involved area showed the presence of necrotic lacunae, with infiltration of lymphocytes and histiocytes. In nine cases, there was histological or cytological diagnosis of suspicious osteomyelitis. No correlation was observed between the intraoral lesions and myelosuppression secondary to antineoplastic therapy. Conclusion: Based on the patients' respective histories, clinical presentations and responses to surgical and antibiotic treatments, it appears that the pathogenesis of this osteonecrotic process is most consistent with localized vascular insufficiency. In our opinion, the mechanism by which bisphosphonates compromise bone vascularity may be related to their effect on the osteoclasts. The potent bisphosphonate-mediated inhibition of osteoclast function serves to decrease bone resorption and inhibit normal bone turnover remodeling, resulting in microdamage accumulation and a reduction in some mechanical Properties of the bone.