Aim and objective: This case report aims to discuss a case of chronic osteomyelitis with proliferative periostitis (COPP) in which cone-beam computed tomography (CBCT) played a key role in the diagnosis and identification of the disease. Background: Osteomyelitis is frequently seen in the maxillofacial region, with the mandible being more affected as compared to the maxilla. Chronic osteomyelitis with proliferative periostitis is often seen in children and young adults, which occurs due to the spread of infection from a bacterial focus. Case description: A 12-year-old boy presented with a swelling on the right side of the mandible. Extraorally, the swelling appeared diffuse, non-tender, hard on palpation, and was associated with right submandibular lymphadenopathy. Intraorally, a hard bony protrusion was found on the buccal aspect of the edentulous space of the first premolar region obliterating the vestibular depth. It was provisionally diagnosed to be a case of chronic alveolar abscess with respect to deciduous molar, with a suspicion of some underlying bony pathology. Blood investigations showed a raised value of erythrocyte sedimentation rate and alkaline phosphatase. Cone-beam computed tomography examinations showed bony laminations parallel to each other and the underlying cortical bone in the axial and sagittal images and these were present both buccally and lingually. The CBCT descriptions led to the diagnosis of Garre's osteomyelitis in this case which was later confirmed by histopathological examination. Conclusion: The detailed imaging as well as the three-dimensional reconstruction of the images has helped to reach out to a differential diagnosis in this case. Clinical significance: This case report emphasizes the importance of newer techniques such as CBCT in reaching out at a diagnostic conclusion in challenging clinical cases.