PP171: Necrosis of the jaws after bisphosphonate and denosumab administration in osteoporotic patients (two case reports)

Introduction Both bisphosphonates (BP) and monoclonal antibodies are effective therapeutic agents for the treatment of severe osteoporosis but can lead to drug-related osteonecrosis of the jaws (DRONJ). The advantage of the monoclonal antibody denosumab is its rather short half-life (26 days vs. 10 yrs in BP). We report two patients where both agents had been administered. Case 1 In spite of 10 years of oral BP an 82 years old female patient suffered a vertebral compression fracture 2 years ago. Because of decreased renal function BP was stopped and denosumab 60 mg every 6 months was started. No other fracture occurred since then.The patient presented in our Clinic with a large oroantral defect after tooth extraction 6 months before. A piece of necrotic bone dropped out spontaneously. The putrid maxillary sinus was rinsed for several weeks and surgically closed under i.v. antibiotic prophylaxis. Healing was uneventful and prosthetic rehabilitation is under way. Denosumab was discontinued. The patient receives calcium and vitamin D now. Case 2 A 67 year old patient was treated with oral alendronat 70 mg weekly over 6 years because of severe osteoporosis. After a comminuted fracture of the shoulder the medication was changed to denosumab 60 mg every 6 month. 4 months after the extraction of a mandibular molar a painful osteonecrotic area was observed. After surgical decortication and discontinuation of the monoclonal antibody healing was uneventful. Conclusion Close interdisciplinary cooperation between the dentist, the maxillofacial surgeon, the internist and nuclear medicine specialist is mandatory in these patients. Tooth extractions should be performed before systemic treatment for osteoporosis is started. When the patient is already under denosumab any extractions should be performed under antibiotic prophylaxis and care should be taken for good surgical coverage of exposed bone. Discontinuation of denosumab may be beneficial.