Some dentigerous cysts may result in considerable displacement of the involved tooth. Infrequently, a third molar may be displaced to the lower border of the mandible or into the ascending ramus. On the other hand, maxillary anterior teeth may be displaced into the floor of the nasal cavity, while other maxillary teeth may be displaced through the maxillary sinus to the floor of the orbit. Furthermore, larger cysts can lead to resorption of adjacent unerupted teeth. Some dentigerous cysts may also grow to considerable size and produce bony expansion that is usually painless, unless secondarily infected. However, any particularly large dentigerous radiolucency should clinically be suspected of a more aggressive odontogenic lesion such as an odontogenic keratocyst or ameloblastoma. For this reason, biopsy is mandated for all significant pericoronal radiolucencies to confirm the diagnosis. The role of CT (computerized tomography) imaging in the evaluation of cystic lesions has been well-documented. CT imaging aids to rule out solid and fibro-osseous lesions, displays bony detail, and provides precise information about the size, origin, content, and relationships of the lesions.On CT imaging, a mandibular dentigerous cyst appears as a well-circumscribed unilocular area of osteolysis that incorporates the crown of a tooth. Displacement of adjacent teeth may be seen and they may be partly eroded. Dentigerous cysts in the maxilla often extend into the antrum, displacing and remodeling the bony sinus wall. Large cysts which may project into the nasal cavity or infratemporal fossa and may elevate the floor of the orbit can be noted on CT imaging.
In the mandible, buccal or lingual cortical expansion and thinning are noted.On MR imaging, the contents of the cyst display low to intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images. The tooth itself is a zone of signal void. The lining of the cyst is thin with regular thickness and may show slight enhancement after contrast injection. Treatment and Prognosis
The treatment of choice for dentigerous cyst is enucleation along with extraction of the impacted teeth. If eruption of the unerupted tooth is considered feasible, the tooth may be left in place after partial removal of the cyst wall. Orthodontic treatment may subsequently be required to assist eruption. Similarly, if displacement of the associated tooth by the cyst has occurred and extraction may prove to be difficult, orthodontic movement of the tooth to a more advantageous location for extraction may be accomplished. Marsupialization may also be used to treat large dentigerous cysts. This permits the decompression of the cyst, with a resulting decrease in the size of the bone defect. The cyst can then be excised at a later date, with a less extensive surgical procedure. The prognosis for the dentigerous cyst is excellent, and recurrence is rare. This is related to the exhausted nature of the reduced enamel epithelium, which has differentiated and formed tooth crown enamel before developing into a cyst. Nevertheless, several potential complications must be considered. The possibility that the lining of a dentigerous cyst might undergo neoplastic transformation to an ameloblastoma has been well-documented.