Dentigerous cyst, also known as follicular cyst is an epithelial-lined developmental cyst formed by accumulation of fluid between the reduced enamel epithelium and crown of an unerupted tooth. It is formed when there is an alteration in the reduced enamel epithelium and encloses the crown of an unerupted tooth at the cemento-enamel junction. Fluid is accumulated between reduced enamel epithelium and the crown of an unerupted tooth. Dentigerous cyst is the second most common form of benign developmental odontogenic cysts. Dentigerous cyst is the second most prevalent type of odontogenic cysts after radicular cyst. 70 percent of the cases occurs in the mandible. Dentigerous cyst is usually painless. Patient usually comes with a concern of delayed tooth eruption or facial swelling. Dentigerous cyst can go unnoticed and may be discovered coincidentally on a regular radiographic examination. Pathogenesis
Odontogenesis happens by means of a complex interaction between oral epithelium and surrounding mesenchymal tissue. Abnormal tissue interaction during this process can result in ectopic tooth development. Ectopic tooth eruption may result due to pathological process, such as a tumor or cyst or developmental disturbance. The pathogenesis of dentigerous cyst is still controversial. The accumulation of fluid either between the reduced enamel epithelium and enamel or in between the layers of enamel organ seems to be the key to the formation of dentigerous cysts. A potentially erupting tooth on an impacted follicle can obstruct the venous outflow, inducing rapid transudation of serum across the capillary walls. Main suggested that this may exert pressure, causing the accumulation of fluid.
Some dentigerous cysts may result in considerable displacement of the involved tooth. Infrequently, a third molar may be displaced to the lower border of the mandible or into the ascending ramus. On the other hand, maxillary anterior teeth may be displaced into the floor of the nasal cavity, while other maxillary teeth may be displaced through the maxillary sinus to the floor of the orbit. Furthermore, larger cysts can lead to resorption of adjacent unerupted teeth. Some dentigerous cysts may also grow to considerable size and produce bony expansion that is usually painless, unless secondarily infected. However, any particularly large dentigerous radiolucency should clinically be suspected of a more aggressive odontogenic lesion such as an odontogenic keratocyst or ameloblastoma. For this reason, biopsy is mandated for all significant pericoronal radiolucencies to confirm the diagnosis. The role of CT (computerized tomography) imaging in the evaluation of cystic lesions has been well-documented. CT imaging aids to rule out solid and fibro-osseous lesions, displays bony detail, and provides precise information about the size, origin, content, and relationships of the lesions.On CT imaging, a mandibular dentigerous cyst appears as a well-circumscribed unilocular area of osteolysis that incorporates the crown of a tooth. Displacement of adjacent teeth may be seen and they may be partly eroded. Dentigerous cysts in the maxilla often extend into the antrum, displacing and remodeling the bony sinus wall. Large cysts which may project into the nasal cavity or infratemporal fossa and may elevate the floor of the orbit can be noted on CT imaging.