Sine Qua Non: Dentigerous Cyst.

Dentigerous cysts, also known as follicular cysts, are among the most common developmental cysts of the gnathic bones. The majority of cases are clinically asymptomatic and discovered incidentally on panographic radiographs during routine dental care. The cyst appears as a radiolucency, classically unilocular, associated with the crown of an unerupted or impacted tooth. Usually diagnosed in the 2nd-3rd decade, third molars of the mandible are the most commonly affected teeth. Histologically, dentigerous cysts demonstrate a fibrous or fibromyxoid connective tissue wall lined by squamous epithelium, classically lacking rete ridges. Inflammation may introduce histologic changes, however. The differential diagnosis includes hyperplastic dental follicle, periapical or radicular cyst, unicystic ameloblastoma, odontogenic keratocyst, and other odontogenic cysts and tumors. While the findings are generally classic and pose no diagnostic dilemma, the diagnosis is best made in the context of the appropriate clinical and radiographic setting. Submitted tissue with a lack of history, to include a detailed relationship with the affected tooth, may result in misdiagnosis and subsequent confusion for the clinician. So, despite its simple features, dentigerous cysts are not uncommonly mischaracterized. Therefore a review of a classic case of dentigerous cyst is presented.