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):
Cleidocranial dysplasia
Maroteaux-Lamy syndrome
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
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:
Ameloblastoma [2]
Squamous cell carcinoma[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