Central ossifying fibroma

Central ossifying fibroma (COF) is a rare benign lesion that typically affects young adults, with the highest incidence occurring between the ages of 20 and 40. It shows a distinct predilection for females, with a reported female-to-male ratio of 2:1. This fibro-osseous tumor is most commonly found in the mandible, particularly in the posterior regions, such as the molar or premolar areas, although it can also affect the maxilla. The condition has no strong racial or ethnic predisposition, though studies suggest higher prevalence in certain populations, such as those in South Asia. == Etiology and pathogenesis ==

Etiology The exact etiology of COF is not fully understood, but it is believed to arise from the mesenchymal tissues of the periodontal ligament or adjacent bone. Developmental anomalies, such as metaplastic changes in these tissues, contribute to the formation of the lesion. Hormonal influences may further contribute, as evidenced by the higher prevalence of COF in young women, although additional research is needed to establish a definitive link. Pathogenesis The pathogenesis of COF begins with the proliferation of mesenchymal cells in the periodontal ligament or adjacent bone, leading to fibrous tissue formation that undergoes metaplastic transformation into bone or cementum-like material . Initially composed of cellular fibrous tissue, the lesion gradually ossifies, resulting in varying amounts of bone and cementum-like deposits . It grows slowly, often causing cortical plate expansion and clinical signs such as facial asymmetry or swelling . Histologically, COF shows a well-defined fibrous stroma with calcified areas ranging from spongy to compact bone . Radiographically, it appears as a well-circumscribed radiolucent area with mixed radiopaque features, characteristic of fibro-osseous lesions. == Classification and clinical presentation ==

There are four distinct clinicopathologic entities for ossifying fibroma of the craniofacial skeleton: cemento-ossifying fibroma [COF], which is an odontogenic ossifying fibroma; trabecular juvenile ossifying fibroma [TrJOF]; psammomatoid juvenile ossifying fibroma [PsJOF]; and extragnathic adult ossifying fibroma. Cemento-Ossifying Fibroma Cemento-ossifying fibroma (COF) typically presents as a painless jaw swelling, often detected incidentally on radiographs. It predominantly affects the mandible more than the maxilla, with the highest incidence in the third and fourth decades of life and a marked female predilection (female-to-male ratio up to 5:1). Tooth displacement is common, while root resorption is less frequently observed. The lesion is also known as juvenile aggressive or juvenile active ossifying fibroma. Trabecular Juvenile Ossifying Fibroma (TrJOF) TrJOF is histologically characterized by immature trabeculae of woven bone lacking osteoblastic rimming, set within a highly cellular fibrous stroma with strands of immature osteoid. The average age range reported in case series is 8.5 to 12 years. Clinically, TrJOF presents as a painless but progressively enlarging mass. In maxillary cases, symptoms like epistaxis and nasal obstruction may occur. Radiographically, the lesion appears large and may cause cortical thinning or perforation. It may show varying radiolucent to radiopaque patterns depending on the degree of calcification, including a ground-glass or multilocular honeycomb appearance. Most cases originate in the paranasal sinuses, particularly the ethmoid and frontal sinuses [7,13]. Around 10% arise in the calvarium. Mandibular involvement is rare—Makek reported 7% of cases, while a later study found one in three cases involved the mandibular ramus. Reported locations include the frontal, parietal, temporal, sphenoid, and occipital bones. Clinically, patients may present with localized swelling, pain, headaches, motor disturbances, exophthalmus, diplopia, and mild spastic hemiparesis . The median duration of symptoms is 3.2 years (range: 1–10 years) . Radiographically, these lesions appear as well-defined osteolytic areas with variable degrees of radiopacity. == Radiographic features ==

The radiographic features of central ossifying fibroma can be categorised according to the stages. In its early stages, central ossifying fibroma (COF) appears as a small, well-defined radiolucent lesion due to its fibrous tissue content. Differential diagnoses at this stage include periapical pathology, central giant cell granuloma, and ameloblastoma. As the lesion matures, it exhibits a mixed radiolucent-radiopaque appearance due to progressive calcification. With growth, it may cause tooth displacement, root resorption, inferior displacement of the mandibular canal, and loss or alteration of the lamina dura of adjacent teeth. File:Panoramic_radiograph_showing_a_radiolucency_around_the_distal_root_of_the_first_mandibular_molar.png|thumb|Panoramic radiograph showing a radiolucency around the distal root of the first mandibular molar and Cone Beam CT (CBCT) plays a crucial role in its accurate diagnosis and assessment. == Histopathology ==

Cemento-ossifying fibroma is a well-demarcated lesion, often encapsulated by a thin fibrous capsule and sharply separated from adjacent normal bone. It shows significant internal variation, with differing amounts of fibrous and mineralized tissue—even within the same lesion. Mineralization is often more prominent centrally and typically includes osteoid, woven to lamellar bone, and dense basophilic cementum-like calcifications. Bony trabeculae may fuse into broad sheets or form thick, anastomosing strands. Osteoblastic rimming is commonly seen around bone trabeculae. The stroma is fibroblastic and may exhibit areas of hypercellularity and nuclear hyperchromasia; however, mitotic activity is rare and cellular atypia is minimal . The mineralized component may include acellular or paucicellular cementum-like spheres along with bone structures . Histological overlap can exist among subtypes: psammomatoid and trabecular JOF may exhibit features resembling COF, and vice versa. In syndromic cases, such as gnathodiaphyseal dysplasia, COF lesions appear more fibrous with basophilic, acellular bone droplets and spherical ossicles, but histologically resemble nonsyndromic counterparts . == Diagnosis, management and treatment ==

Central Ossifying Fibroma (COF) typically presents as a painless swelling in the posterior mandible, though maxillary involvement can also occur. Larger lesions may lead to facial asymmetry and displacement of adjacent teeth. Radiographically, COF appears as a well-circumscribed, mixed radiolucent–radiopaque lesion with a characteristic sclerotic border, and the degree of radiopacity reflects the stage of mineralization. Cone-beam computed tomography (CBCT) offers detailed evaluation of cortical expansion, root displacement, and internal architecture. Histologically, COF comprises a fibrocellular stroma with varying degrees of ossification, including trabecular or lamellar bone and cementum-like material. Differentiation from other fibro-osseous lesions—such as fibrous dysplasia and cemento-ossifying fibroma—requires histopathological assessment. Treatment depends on lesion size, location, and symptoms. Small to moderate lesions are typically managed with enucleation and curettage, whereas large lesions with significant bone expansion may require segmental resection and reconstruction to restore function and aesthetics. Postoperative follow-up is critical, as incomplete removal may lead to recurrence, although COF generally has a low recurrence rate. Regular clinical and radiographic monitoring for at least five years is recommended. With complete excision, the prognosis is typically favorable. == Prognosis, research and future directions ==

Central ossifying fibroma (COF) is a benign fibro-osseous lesion of the jawbone, typically managed by surgical excision, including enucleation or resection. Conservative surgery often results in cure with low recurrence, In children, poorly defined radiographic margins and curettage are linked to higher recurrence, while radical resection has the lowest recurrence rate. In select cases, especially where tooth preservation is desired, conservative management with prolonged monitoring can be effective. Research on COF spans multiple domains. Clinicopathologic studies examine presentation and histology across age groups. COF commonly affects females in the second to fourth decades, with mandibular predilection, particularly in premolar–molar regions, although a pediatric study noted male predominance. Its etiology remains unclear, but possible origins include multipotential mesenchymal cells of the periodontal ligament, with trauma and HRPT2 gene mutations also implicated. Radiographically, COF may appear radiolucent, mixed, or radiopaque ,, and histologically, it features bone or cementum-like material in a fibrocellular stroma. Surgical approaches range from curettage to radical resection, with reconstruction using free tissue grafts and platelet-rich gel (PRG) to enhance bone healing. Future research should focus on genetic mechanisms and risk factors. long-term outcomes of conservative treatment, and refinement of surgical techniques, including 3D printing for planning and PRG for regeneration. Advances in imaging and AI may improve early diagnosis and differentiation from similar lesions. Understanding recurrence mechanisms is vital for optimizing treatment and follow-up, and studies on quality of life and prosthetic rehabilitation, including dental implants, will support better clinical decision-making. ==References==