|Discussion: The second most common odontogenic cyst is the dentigerous cyst, which develops within the normal dental follicle that surrounds an unerupted tooth.Dentigerous cysts are the most prevalent type of odontogenic cysts attached at the cemento-enamel junction.They are most commonly seen in mandible third molar and in maxillary canine.Males are more commonly affected.,in the third decade.A dentigerous cyst is an odontogenic cyst - thought to be of developmental origin - associated with the crown of an unerupted (or partially erupted) tooth. The cyst cavity is lined by epithelial cells derived from the reduced enamel epithelium of the tooth forming organ. Regarding its pathogenesis, it has been suggested that the pressure exerted by an erupting tooth on the follicle may obstruct venous flow inducing accumulation of exudate between the reduced enamel epithelium and the tooth crown. The dentigerous cyst is not thought to be neoplastic. It most frequently is found in areas where unerupted teeth are found: mandibular third molars, maxillary third molars, and maxillary canines, in decreasing order of frequency. These cysts can grow very large and can move teeth, but, more commonly, they are relatively small. Most dentigerous cysts are asymptomatic, and their discovery is usually an incidental finding on radiography
The usual radiographic appearance is that of a well-demarcated radiolucent lesion attached at an acute angle to the cervical area of an unerupted tooth. The border of the lesion may be radiopaque. The radiographic differentiation between a dentigerous cyst and a normal dental follicle is based merely on size. Radiographically, a dentigerous cyst should always be differentiated from a normal dental follicle.