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.
Histologic examination reveals a more collagenized fibrous connective tissue wall, with a variable infiltration of chronic inflammatory cells. Cholesterol slits and their associated multinucleated giant cells may be present and are generally associated with the connective tissue wall. The cyst is lined mostly or entirely by non-keratinizing squamous epithelium which display varying amounts of hyperplasia with the development of anastomosing rete ridges and more definite squamous features. Dentigerous cysts presenting with these features may histologically be indistinguishable from radicular cysts. A keratinized surface is occasionally present, which must be differentiated from those observed in the odontogenic keratocyst(OKC). Focal areas of mucus cells or rarely, ciliated columnar cells may be found in the epithelial lining of dentigerous cysts. In addition, small nests of sebaceous cells infrequently may be present within the fibrous connective tissue wall. These mucous, ciliated and sebaceous elements are postulated to represent the multipotentiality of the odontogenic epithelial lining in a dentigerous cyst. One or several areas of nodular thickening may be seen on the luminal surface in the gross examination of the fibrous wall of a dentigerous cyst. Careful examination of these areas microscopically is mandatory to rule out the presence of early neoplastic change. As the dental follicle surrounding the crown of an unerupted tooth usually is lined by a thin layer of reduced enamel epithelium, this may render it difficult to distinguish a small dentigerous cyst from a normal or enlarged dental follicle based on microscopic features alone.