FIBROUS DYSPLASIA OF THE LEFT HEMIMANDIBLE PRESENTING AS CHRONIC PAIN AFTER DENTAL IMPLANT: A MULTIDISCIPLINARY CASE REPORT: S. Conte1, M. Val2 | 1UOC Terapia del Dolore, Aulss2 Marca Trevigiana, Ospedale Ca' Foncello Treviso, Italy; 2UOC Chirurgia Maxillo Facciale, Aulss2 Marca Trevigiana, Ospedale Ca' Foncello Treviso, Italy

Introduction. Fibrous dysplasia (FD) is a benign skeletal disorder in which normal bone is replaced by fibrous tissue, often presenting diagnostic challenges in the craniofacial district. Mandibular involvement may closely mimic infectious or inflammatory conditions such as osteomyelitis, leading to significant diagnostic delays and inappropriate treatment (1, 2).Methods. We report a case of a 61-year-old woman referred in 2022 for chronic left mandibular pain that had begun 4 years earlier following dental implant placement in the region of tooth 36. Pain initially improved with heat and worsened with cold, before becoming constant. Diagnostic workup included facial CT scans (2022, 2023, 2025), bone scintigraphy, bone biopsy, comprehensive infectious disease evaluation (inflammatory markers, complete bacteriological panel, blood cultures), and osteometabolic assessment. The patient was jointly managed by the Maxillofacial Surgery Unit and the Pain Therapy Unit at ULSS2 Marca Trevigiana, Ca' Foncello Hospital, Treviso.Results. CT imaging revealed thickening of the left hemimandibular periosteum on the vestibular and mandibular aspects, with progression on 2023 follow-up. Bone scintigraphy demonstrated focal radiotracer hyperaccumulation in the posterior left hemimandible, consistent with bone remodeling and osteogenic reaction. Osteomyelitis was initially suspected but excluded by biopsy and negative infectious workup. Fibrous dysplasia was then hypothesized following osteometabolic evaluation. Intravenous zoledronic acid (Aclasta) was administered in 2023 and 2024, combined with chronic cholecalciferol supplementation. Methylprednisolone and gabapentin provided symptomatic relief during the diagnostic phase. A control CT in 2025 confirmed stabilized periosteal reaction with bone condensation of the left hemimandible, consistent with FD. Pain resolved completely and both medications were successfully tapered and discontinued.Conclusions. This case underscores the diagnostic complexity of mandibular fibrous dysplasia, which may present as chronic neuropathic-like pain following dental procedures and initially mimic infectious conditions. A multidisciplinary approach involving maxillofacial surgery, pain management, and osteometabolic medicine proved essential for accurate diagnosis and effective treatment. Bisphosphonate therapy with zoledronic acid achieved disease stabilization and complete pain resolution.