There were three possible mechanisms exist. Firstly, surrounding the crowns of affected teeth, the intrafollicular developmental dentigerous cysts may be formed. These cysts may be secondarily inflamed and infected as a result of periapical inflammation spreading from non vital deciduous predecessors. Benn and Altini (1996) claimed that this possibility was unlikely as all the cases reported were not associated with tooth impaction. Secondly, radicular cysts developed at the apices of non vital primary teeth. These radicular cysts may fuse with the follicles of the unerupted successors, causing the eruption of the successors into the cyst cavity. This may result in the formation of extrafollicular dentigerous cyst. Shear regarded this to be exceptionally rare because radicular cyst is uncommon in the primary dentition. The third possibility is that periapical inflammation could be of any source but usually from a non vital deciduous tooth spreading to involve the follicles of unerupted permanent successors. The inflammatory exudate causes separation of reduced enamel epithelium from the enamel with resultant cyst formation. Clinical Features
The dentigerous cyst commonly involves a single tooth and rarely affects multiple teeth. The most frequently involved tooth is the mandibular third molar followed by the maxillary canine, but they may be associated with supernumerary or ectopic tooth. Any permanent tooth can be involved. Regezi and Sciubba stated that the impacted teeth were most commonly seen in the third molar and maxillary canine teeth, and hence dentigerous cysts occur most frequently in these teeth. The involved teeth may be displaced into ectopic positions.
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.