Introduction: Dentigerous cyst is a pathological epithelial cavity that surrounds an unerupted tooth crown. Dentigerous cysts are usually associated with impacted teeth, mandibular third molars, first and second premolars and canines. Dentigerous cysts can occur at any age, but most cases of these cysts occur at the age of approximately 20 years. Men are affected more often than women. Purpose.To find out how the mechanism of dentigerous cysts. The cyst cavity is lined with epithelial cells derived from the epithelial enamel that is reduced from the tooth-forming organs. According to its pathogenesis, the pressure exerted by an erupted tooth on the follicle can block venous flow leading to accumulation of exudate between the reduced enamel epithelium and the crown of the tooth. These cysts are mostly due to fluid accumulation either between the reduced enamel epithelium and the enamel or between the layers of the enamel organ. This fluid accumulation occurs as a result of the pressure exerted by the erupting tooth on the affected follicle, which blocks venous flow, thus inducing rapid transudation of serum in the capillary walls. Discussion: The expansion of the dentigerous cyst causes the release of bone resorbing factor and an increase in the osmolarity of the cyst fluid as a result of the discharge of inflammatory cells, the discharge of residual epithelial enamel and tooth enamel, and desquamation of epithelial cells into the lumen of the cyst. In theory, the fluid will cause cystic proliferation. because the hyperosmolar content produced by cellular breakdown and cell products causes an osmotic gradient to pump fluid into the lumen of the cyst or it can also be said that an increase in the osmolarity of cyst fluid is the result of a shortcut to inflammatory cells and desquamation of epithelial cells into the lumen of the cyst resulting in a dentigerous cyst. Conclusion: The dentigerous cysts that surround the unerupted dental crowns are caused by the accumulation of fluid either between the reduced enamel epithelium or between the layers of the enamel organs. Dentigerous cysts can cause infection, pain, swelling, root dislocation, and resorption of adjacent tooth roots.