Dentigerous Cyst

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  • A developmental odontogenic cyst that surrounds the crown of an unerupted tooth
  • The cyst is attached to the neck of the tooth (CEJ), prevents its eruption and may displace it for considerable distance
  • Considered a dilatation of the follicle hence also known as a follicular cyst

Epidemiology[edit]

  • Second most common cyst of the jaw (most common of developmental aetiology) - 10-15% of all jaw cysts
  • ♂ > ♀ (1.5:1)[1]
  • 80% occur in the mandible[1]
    • Affect permanent teeth
    • Mandibular 3rd molar (77%) > maxillary 3rd molar (11%) > maxillary canine (5%)[1]
  • Most common in age 20-50yrs

Clinical Features[edit]

  • Cyst usually affects single tooth (rarely affects multiple teeth)
  • Associated with unerupted teeth - but as lower third molar is most commonly affected, patients are commonly unaware
  • Usually asymptomatic until the swelling becomes noticeable
  • When large an intra-oral swelling may become noticeable (usually painless)
  • Very large or infected cysts may cause extra-oral swelling
  • Usually an incidental finding on routine radiography or when looking for a missing tooth
  • Infected cysts also associated with rapid growth and pain
  • May displace the tooth with which they are associated and tilt adjacent teeth
    • In the maxilla, teeth may be displaced into the sinus therefore can present with classic symptoms of sinus disease
  • Rarely cause resorption of adjacent tooth roots/tooth enclosed within cyst

Differential Diagnosis[edit]

  • Other cysts of the jaws
  • Specifically odontogenic keratocysts and ameloblastomas may occasionally envelope the crown of the tooth and ∴ mimic dentigerous cyst

Aetiology and Pathogenesis[edit]

Aetiology[edit]

  • Dentigerous are developmental anomalies (but some cysts may be induced by inflammation)
  • No genetic defect has been identified
  • Can be associated with various syndromes (consider when multiple lesions are present):
    1. Cleidocranial dysplasia
    2. Maroteaux-Lamy syndrome
    3. Gardener's syndrome

Pathogenesis[edit]

  • Formed by accumulation of fluid between the reduced enamel epithelium and crown of an unerupted tooth
    • Occurs after enamel formation is complete
    • Strong association between failure of eruption of teeth and formation of dentigerous cyst
    • ∴ commonly affects lower third molars and upper canines (teeth that commonly impact)
  • Alteration in the reduced enamel epithelium → encloses the crown of an unerupted tooth at the cemento-enamel junction
  • Intrafollicular fluid accumulates between reduced enamel epithelium and enamel
  • Pressure of tooth on impacted follicle →
    • Obstructs venous outflow
    • Serum transudation
    • Exudation

Investigations[edit]

Orthopantogram of a dentigerous cyst associated with lower right third molar
Histopathology of a dentigerous cyst, showing non-keratinised squamous cell epithelium

Imaging[edit]

Plain film[edit]

  • Commonly an incidental finding on routine intra-oral or panoramic radiographs
  • Common radiographic features:
    • Round radiolucent area (uniformly radiolucent)
    • Unilocular
    • Sharply defined with corticated margins (∵ slow growth)
    • Associated with crown of unerupted permanent teeth

Computed Tomography[edit]

  • Can facilitate diagnosis, and 3D characterisation for surgical planning

Histopathology[edit]

  • Common histopathological findings:
    • Clear yellow fluid (cholesterol)
    • Purulent if infected
    • Lined by flattened, non-keratinized stratified squamous epithelium
    • Continuous with reduced enamel epithelium
    • Mucus and ciliated columnar metaplasia
      • These cells can sometimes be found in the lining of the epithelium
    • Fibrous wall and variable inflammation

Management[edit]

  • Enucleation + extraction of tooth
  • Marsupialization - if tooth is in a favourable position and space is available this may allow tooth to erupt. Also helpful if cyst is large and risks fracture of mandible

Prognosis and Complications[edit]

  • Recurrence is rare
  • Although rare, the lining of a dentigerous cyst can undergo transformation and develop into:
    1. Ameloblastoma [2]
    2. Squamous cell carcinoma[3]
    3. Mucoepidermoid carcinoma[4]

Follow-up[edit]

  • Routine follow-up not needed
  • Suitable for results to be given to patient via remote consultation/mail
  • Be aware that malignancy in the cyst wall is usually unexpected at the time of presentation and the diagnosis is usually made following enucleation - these cases obviously need follow-up

References[edit]