Answer of August 2009
Diagnosis:
Dentigerous Cyst
Discussion:
Cystic lesions in the mandible can be divided into either odontogenic or non-odontogenic in origin. Most of the cystic lesions in the mandibular region is benign and asymptomatic, and so many of these lesions are found incidentally, commonly before dental procedures.
Benign cystic lesions include dentigerous cyst, radicular cyst and odentogenic keratocyte, etc. Because of wide range of differential diagnoses and similar radiological findings, patient’s age at presentation, location of the lesion within the mandible, nature of the lesion, and effects of the lesion to adjacent structures, are important for making a correct diagnosis. However, a definitive diagnosis still cannot be made in some mandibular lesions without biopsy.
Dentigerous cyst is the most common odontogenic cystic lesion in the mandible. It forms as a result of proliferation of epithelium around the crown of a tooth. A dentigerous cyst is classically asymptomatic and could enlarge and displace the adjacent teeth or causing teeth/bone resorption.
Radiologically, they are typically round or oval-shaped cystic lesions, well defined, well corticated, and found around the crown of an unerupted tooth, typically the third molar tooth. The root of the involved tooth is outside the lesion and is in the mandible. These features are almost pathognomonic for a dentigerous cyst. Malignant transformation of a dentigerous cyst is extremely rare. For treatment, surgical enucleation is suggested and a definitive histopathological diagnosis is recommended.