There are several types of odontogenic cysts that can develop: 1) A periapical cyst develops from a periapical granuloma caused by degradation products from a nonvital tooth. 2) A residual cyst can develop months to years after a tooth extraction if the cyst lining is incompletely removed. 3) Dentigerous cysts develop from proliferation of the enamel organ remnant surrounding an unerupted tooth.

1. Causes of odontogenic cyst
Amin Abusallamah

2. 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.

4. Residual cyst
• When the necrotic tooth is
extracted but the cyst lining
is incompletely removed, a
residual cyst may develop
from months to years.

5. 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.

6. Dentigerous cyst
• Dentigerous cyst develops
from proliferation of the
enamel organ remnant or
reduced enamel epithelium.

7. 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.

8. 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.

9. 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

11. Calcifying odontogenic cysts
• COGs are believed to be
derived from odontogenic
epithelial remnants within
the gingiva or within the
mandible or maxilla.

12. • Chapter … 10… pages … 243 -255