Cemento-ossifying Fibroma of Mandible: Report of Two Cases

Cemento-ossifying fibroma (COF) is a bone producing, slow growing, asymptomatic, well-demarcated, benign lesion of the jaw.1 Typically affects female between 20 to 40 years, predilection for the mandible premolar-molar region, causing a painless swelling but undergoes slow expansile growth.2 Most probably tumor originates from periodontal membrane, therefore, with double embryonic origin (ectodermic and mesodermic). In fact, connective tissue of the periodontal membrane can contemporarily elaborate both bone and cementum.3 Bernier hypothesized that the etiopathogenesis of COF in the bone might be caused by an irritant stimulus (such as tooth extraction) which may activate the production of new tissue from the remaining periodontal membrane.4 The etiopathogenesis of extraosseous COF, where there is no periodontal tissue as suggested by Cakir and Karadayi is from embryonic nests 5 and from ectopic periodontal membrane as suggested by Brademann et al6 cytogenetic studies are limited. In one study, 3 orbital COF exhibited balanced translocations with recurring breakpoints at Xq26 and 2q33.7 Dal cin et al also reported an interstitial deletion on chromosome 2 between q31 and q35-36.8 Radiographically, they are well-defined unilocular or multilocular lesion with smooth contour. Depending on the stage of maturation, cemento-ossifying fibroma can be radiolucent, mixed variety to completely radiopaque. Histologically, it appear as well-circumscribed, occasionally encapsulated with various amount of bony trabeculae/ cementum formation in a fibrous stroma.9