Periapical (radicular) cyst• A periapical cyst develops from a preexisting periapical granuloma, which is a focus of chronically inflamed granulation tissue in bone located at the apex of a nonvital tooth.• Periapical granulomas are initiated and maintained by the degradation products of necrotic pulp tissue.
Residual cyst• When the necrotic tooth is extracted but the cyst lining is incompletely removed, a residual cyst may develop from months to years.
Gingival cysts of the newborn• It is believed that fragments of the dental lamina that remain within the alveolar ridge mucosa after tooth formation proliferate to form these small, keratinized cysts.
Dentigerous cyst• Dentigerous cyst develops from proliferation of the enamel organ remnant or reduced enamel epithelium.
Primordial cyst• The primordial cyst develops from the enamel organ of the tooth bud as a result of degeneration of the stellate reticulum in developing tooth bud prior to the calcification of the dental tissues.
Eruption cyst• An eruption cyst results from fluid accumulation within the follicular space of an erupting tooth.• The epithelium lining this space is simply reduced enamel epithelium.
Odontogenic keratocysts• There is general agreement that OKCs develop from dental lamina remnants in the mandible and maxilla. However, an origin of this cyst From extension of basal cells of the overlying oral epithelium has also been suggested.• Genetic
Calcifying odontogenic cysts• COGs are believed to be derived from odontogenic epithelial remnants within the gingiva or within the mandible or maxilla.