IS Case 203: Dentigerous cyst
Imaging Sciences URMC 2008
Publication Date: 2009-05-22
Dentigerous cysts or follicular cysts are the most common of the developmental odontogenic cysts of the jaws. They develop around the crown of an unerupted tooth by expansion of follicle when fluid collects or a space occurs between the reduced enamel epithelium and the enamel of an impacted tooth. They are found most frequently around the crown of the mandibular third molars followed, in order of frequency, by the maxillary canines, maxillary third molars and, rarely, the maxillary right central incisor. These cysts are often asymptomatic unless there is an acute inflammatory exacerbation. Swelling, teeth displacement, tooth mobility, and sensitivity may be present if the cyst reaches a size larger than 2 cm in diameter. A follicular cyst may become extremely large, often distorting the roots of adjacent teeth and remodeling the mandible. However, the cortical bone is usually preserved. This condition is typically diagnosed in patients between 30 and 40 years of age.
MR findings on T1WI show low to intermediate signal intensity within cyst. T2WI show increased signal intensity within cyst. Associated unerupted tooth can present as focal lack of signal on both T1 & T2 images.
Differential diagnoses include radicular cyst, odontogenic keratocyst, and ameloblastoma.
Complications associated with dentigerous cysts include pathologic bone fracture, loss of the permanent tooth, bone deformation, and development of squamous cell carcinoma, mucoepidermoid carcinoma, and ameloblastoma.
The treatment indicated for dentigerous cysts are surgical removal of the cyst, avoiding damage to the involved permanent tooth; enucleation of the cyst, along with removal of the involved tooth; or the use of a marsupialization technique, which removes the cyst while preserving the developing tooth.
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