Medication-Related Osteonecrosis of the Jaw at the Site of a Presumed Pre-Existing Mandibular Dense Bone Island: A Longitudinal Cone-Beam Computed Tomography Case Report

Objective:Rare disease Background:Dense bone island (DBI), also known as idiopathic osteosclerosis, is a localized intraosseous radiopacity of unknown etiology that is typically asymptomatic and incidentally detected.It most commonly occurs in the posterior mandible as a well-defined, homogeneous radiopaque lesion without cortical disruption or effects on adjacent structures.Its behavior in patients receiving antiresorptive therapy remains largely unexplored.Medicationrelated osteonecrosis of the jaw (MRONJ) is a recognized complication associated with antiresorptive agents, including denosumab and bisphosphonates.This case report describes a 70-year-old woman receiving longterm denosumab therapy for osteoporosis who developed MRONJ at the site of a pre-existing mandibular lesion provisionally diagnosed as a DBI and was evaluated using cone-beam computed tomography (CBCT). Case Report:A 70-year-old woman receiving long-term denosumab therapy for osteoporosis developed Stage 2 MRONJ at the site of a presumed pre-existing mandibular DBI.CBCT initially demonstrated a hyperdense lesion in the left posterior mandible.Four years later (at age 74), the patient presented with an intraoral fistula.Follow-up CBCT revealed a mixed osteolytic-osteosclerotic process at the same site, with mandibular canal involvement, and sequestrum formation.Surgical excision and histopathologic examination confirmed MRONJ. Conclusions:This case highlights the value of longitudinal CBCT in documenting the radiographic evolution of MRONJ at the site of a previously identified lesion provisionally diagnosed as a DBI.However, the observed temporal and spatial association does not establish a causal relationship between the baseline lesion and subsequent development of MRONJ.