Dentigerous Cyst

Definition

An Odontogenic cyst that surrounds the crown of impacted tooth, caused by fluid accumulation between the reduced enamel epithelium and the enamel surface, resulting in a cyst in which the crown is located within the lumen.This is the most common developmental Odontogenic cyst.Also called as Follicular Cyst

Etiology:

Develops by accumulation of fluid between the reduced enamel epithelium and the tooth crown after crown formation.

Common Sites:

• Mandibular and Maxillary Third Molars and Maxillary cuspid regions
• Dentigerous cyst always is associated with the crown of a normal permanent tooth.

Clinical Features:

It is always associated initially with the crown of an impacted, embedded or unerupted tooth. Dentigerous cyst may also be found enclosing a complex compound odontoma or imvolving a supernumerary tooth. Multiple bilateral cysts usually associated with syndromes like Cleidocranial dysplasia & Maroteaux-Lamy Syndrome.
Dentigerous Cyst is an Aggressive Lesion and shows rapid Expansion of bone with facial asymmetry,Extreme Displacement of teeth,Severe root resorption and in some cases displacement of roots into distant sites. Pain occurs in cases of infection.
Dentigerous Cyst involving an Unerupted Mandibular Third molar results in Hollowing out of Entire Ramus upto the coronoid process, Expansion of cortical plate, Displacement of Third molar which sometimes gets compressed against the inferior border of the mandible.
Dentigerous Cyst involving an Unerupted Maxillary Cuspid may cause Expansion of the Anterior maxilla which resembles Acute Sinusitis or Cellulitis,No pain unless Secondarily infected Seen mostly in the second and third decades of life with Male : Female ratio of– 3:2

Radiographic Features:

Radiolucent area is associated with un-erupted tooth crown.

Radiolucency Symmetrically surrounds the tooth crown.

Radiolucent space will be more than 5mm   

Radiologic variants:

Central Variety: Crown is enveloped symmetrically, this pushes the crown towards the lower border of the Mandible

Lateral Type: Dilatation of the follicle on one aspect of the crown

Circumferential Type: The follicle expands in a manner which appears to envelope the Entire tooth. Sometimes the radiolucent area is surrounded by a thin sclerotic line representing bony reaction.

Histologic Features:

Thin connective tissue wall with a layer of stratified squamous epithelium lining the lumen Thin layer of epithelium, 2 – 3 layers thick with no rete ridge formation, unless infected Presence of odontogenic epithelium in islands in the connective tissue wall – which may give rise to the development of Ameloblastoma.
Rushton Bodies – Peculiar, linear, often curved, hyaline bodies with variable staining of uncertain origin and unknown significance, but probably of hematogenous origin, found within the lining epithelium – especially in areas of inflammation.

The cystic lumen contains thin watery yellow fluid, occasionally blood stained. Aspirated fluid protein content is about >4gm/100 ml. Connective tissue is thick and composed of fibrous tissue.

Complications

1) Development of Ameloblastoma - From lining epithelium and in the islands of odontogenic epithelium.
2) Development of Mucoepidermoid Carcinoma & Epidermoid Carcinoma

Treatment

Mostly basesd on size of the lesion
Smaller lesions: Enucleation
Larger lesions: Marsupilisation and Surgical Curettage
Recurrence is rare unless there is neoplastic transformation.