MON-513 Osteonecrosis after Successful Osseointegrated Dental Implantation

Introduction: Medication-related osteonecrosis of the jaw (MRONJ) is a rare complication of antiresorptive medications. Although typically occurring after invasive dental procedures, there is limited data suggesting MRONJ risk in patients with a successfully osseointegrated dental implant. In this case report, we present the clinical presentation, radiological, pathological, and biochemical data of MRONJ presenting years after successful dental implantation while taking antiresorptive medication for the treatment of osteoporosis. Case Presentation: 77 year-old woman underwent titanium dental implant installation to replace a missing mandibular right first molar with uncomplicated postoperative course in 2011, which healed well. Her rheumatologist prescribed ibandronate in 2010 for treatment of osteopenia. In 11/2014 switched to denosumab 60 mg SQ every 6 months. In 2015, she was referred for evaluation of hyperparathyroidism and also transferred osteoporosis care. With adequate clinical response and tolerance to denosumab, she continued the medication. In 6/2018 she had parathyroidectomy to treat primary hyperparathyroidism after an episode of flank pain suspicious for nephrolithiasis. She experienced no further dental complications until jaw pain developed in 2/2018. Periapical radiographs in 4/2018 showed no signs of bone loss or pathology. However, soft tissue papillae between the implant and the mandibular right second molar was inflamed and bled on contact. Despite removal of granulation tissue, the gingiva continued to bleed. Oral antibiotics were empirically prescribed. Cone beam CT scan in 6/2018 showed an altered osseous trabecular pattern without frank bone loss between the implant and right second mandibular molar, suggestive of MRONJ. Denosumab was discontinued(last dose 5/2018). In 7/2018, the dental implant was removed and bone attached to the implant was submitted for histologic evaluation, demonstrating chronic mucositis and sequestra consistent with MRONJ. In 9/2018, the patient developed purulent drainage at the removal site despite oral antibiotic therapy. On repeat CT scan, progressive bone loss and soft tissue proliferation was noted at the prior site of implant and extending slightly more posterior near the right second mandibular molar. She started IV antibiotics with complete resolution of symptoms to date. This case demonstrates osteonecrosis occurring at the site of a previously successful 7-year-old osseointegrated dental implant in a patient on uninterrupted antiresorptive therapy for 8 years.