A non-malignant (benign) neoplasm of connective tissue: they are rare in the oral cavity and most nodules of fibrous tissue are reactive hyperplasia to trauma and not neoplasms. An ameloblastic fibroma is a circumscribed benign odontogenic neoplasm composed of cellular fibrous tissue resembling the dental papilla containing small islands of odontogenic epithelium. They are normally found in the mandible over unerupted molars of young patients and appear as a circumscribed radiolucency; the soft tissue mass can cause expansion of the bone cortex. Treatment is by conservative surgical excision. An ossifying fibroma ( cemento-ossifying fibroma) is a well-demarcated lesion composed of cellular fibrous tissue in which calcification is laid down and which arises in the periodontal ligament of young individuals. They are most common in the posterior mandible and cause jaw expansion; radiographically they appear as a well-defined mixed radiolucency or radiopacity and are treated by surgical removal. An odontogenic fibroma is a benign odontogenic neoplasm of unknown aetiology derived from odontogenic connective tissue: it contains scattered islands of odontogenic epithelium and foci of calcification; treatment is by enucleation or curettage.