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The dentigerous (follicular) cyst is recognized as one of the most common lesions of the jaws. Clinical, radiographic, histologic, and prognostic characteristics are well established for medium to large pericoronal cysts that are lined by nonkeratinized stratified squamous epithelium. However, it can be difficult, if not impossible, to distinguish between a small dentigerous cyst and a large dental follicle despite the availability of both radiographic and histologic information. Epidemiologic data derived from a comparative study of 1662 dentigerous cysts and 824 dental follicles showed considerable overlap in age distribution and site predilection and were therefore of minimal use in reaching a final diagnosis. At present, it appears that identifying a cystic cavity at the time of surgery may be the only reliable way to arrive at a definitive diagnosis when radiographic and histologic features are insufficient to distinguish between a small dentigerous cyst and a large dental follicle.

The diagnoses of 40,000 consecutively accessioned oral biopsies from the Oral Pathology Diagnostic Service, University of Western Ontario, London, Canada, were reviewed. All odontogenic neoplasm, neoplasm-like lesions (tumors), and true cysts of the oral tissues and jaws were listed. Clinical data were reviewed, and microscopic diagnoses were confirmed for cases in which diagnoses were ambiguous. Records of all cases were examined to identify distant referrals that were not representative of the study population. Of a total of 445 (1.11%) odontogenic tumors, 392 (0.98%) were lesions from patients in the usual local drawing area of the biopsy service; 53 were referred from distant centers. From the local population, odontomas were by far the most common tumor (51.53%) followed by ameloblastomas (13.52%) and peripheral odontogenic fibromas (8.93%). Locally, radicular (periapical) cysts were the most common odontogenic cyst (65.15%) followed by the dentigerous cyst (24.08%) and the odontogenic keratocyst (4.88%). The most common nonodontogenic cyst was the nasopalatine duct cyst that accounted for 73.43% of this subset of cysts. Surprisingly few studies of this type are available, especially for odontogenic tumors. These data are important to assess geographic differences in the incidence of lesions and to allow clinicians to make realistic judgments in counseling patients before biopsy about the probability of diagnosis and risks associated with nonspecific clinical or radiographic lesions.