DENTIGEROUS CYST: CLINICAL FEATURES, RADIOLOGY, HISTOPATHOLOGY & TREATMENT
Author: Sanketh DS, MDS
INTRODUCTION AND ETIOLOGY
Dentigerous cyst could be defined as an odontogenic cyst that envelops the crown of an unerupted tooth, caused due to accumulation of fluid between the reduced enamel epithelium and the enamel. This results in a cyst attached to the tooth at the cement-enamel junction, with the crown enclosed in its lumen. However, little is known as to what causes the separation of reduced enamel epithelium from the enamel allowing this accumulation of fluid.
There is another hypothesis, which states that the dentigerous cyst may develop around a permanent tooth as a result of periapical inflammation from an overlying primary tooth. This may be due to the permanent tooth erupting into an already formed radicular cyst around the apex of a primary tooth. However, these are not to be reported as dentigerous cysts.
This cyst is the most common odontogenic cyst of developmental origin comprising 20% of all jaw cysts. Dentigerous cyst is always associated with a permanent tooth and is seldom seen in relation with primary a tooth.
Most dentigerous cysts occur in the second to third decades of life with a slight male predilection. Though these cysts may be associated with any unerupted tooth, the mandibular third molars are most commonly involved, approximately 65% of the times, followed by the maxillary cuspids, maxillary third molars and mandibular second premolars. They may rarely be found involving a supernumerary tooth or an odontoma. Usually, dentigerous cysts are asymptomatic and are discovered during routine dental radiographic investigations. Large dentigerous cysts may cause swelling of the jaws and may result in facial asymmetry. Dentigerous cysts that may be infected, may cause pain and swelling.
Radiographically, the lesion would show a unilocular radiolucent area enveloping the crown of an unerupted tooth. This radiolucency has a well defined and corticated border. The lesion may sometimes displace the involved tooth to a considerable distance and may cause root resorption of adjacent teeth. Large dentigerous cysts are uncommon, and such lesions associated with an unerupted tooth may be odontogenic keratocysts or unicystic ameloblastomas. Hence it is important that a diagnosis is not made on a radiographic evidence alone.
There are essentially three types of radiographic presentations for a dentigerous cyst. The most common is the “central” variety where the radiolucency extends upto the cement-enamel junction enveloping the tooth crown. The “lateral” variety is usually associated with mesio-angular partially erupted impacted third molars, where the radiolucency extends laterally along the root and partially surrounds the crown. The third, is the “circumferential” variety where the radiolucency may extend along the roots and appears to cover the root. Another significant consideration for a radiographic diagnosis of dentigerous cyst is that the radiolucent space surrounding the crown should be >5mm in diameter, as the normal follicular space surrounding a tooth could be 3-4mm in diameter.
Histologic examination usually reveals an epithelial lining that is non-keratinised and 2-4 layers in thickness. The epithelium may be flat or cuboidal and essentially represents the reduced enamel epithelium. On occasions, numerous mucus cells and ciliated cells may be found in the lining epithelium. The epithelium-connective tissue interface is flat and the fibrous connective tissue is loosely arranged and may harbour small islands or cords of odontogenic epithelial rests. Inflammation of the cyst may result in the infiltration of inflammatory cells in the stroma and the connective tissue may become more collagenized. Also,the epithelial lining may show breaks in between and hyperplasia at times.
TREATMENT AND PROGNOSIS
Removal of the tooth along with enucleation of the lesion is a definitive treatment most of the times. In case of large cysts, decompression is done to reduce the size of the cyst and then totally removed at a later date. Overall, the prognosis for dentigerous cyst is excellent and recurrence is seldom reported. Potential complications that may arise from the transformation of the epithelial lining of a dentigerous cyst include ameloblastoma, squamous cell carcinoma! Also, there may be a potential for the development of an intraosseous mucoepidermoid carcinoma from the mucus cells that may be present in the dentigerous cyst lining.
Cysts of oral and maxillofacial regions. Shear and Speight. 4th Edition.
Shafer’s Textbook of Oral Pathology.Rajendran and Sivapathasundaram.6th Edition.
Oral and Maxillofacial Pathology.Neville,Damm,Allen,Chi. South Asian Edition.
Oral Pathology: Clinicopathologic correlations.Regezzi,Sciubba,Jorda.5th Edition.
Contemporary Oral and Maxillofacial Pathology, Sapp,Eversole,Wysoki.2nd Edition.
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