RELATIVE INCIDENCE OF ODONTOGENIC-TUMORS AND ORAL AND JAW CYSTS IN A CANADIAN POPULATION

The diagnoses of 40,000 consecutively accessioned oral biopsies from t he Oral Pathology Diagnostic Service, University of Western Ontario, L ondon, Canada, were reviewed. All odontogenic neoplasms, neoplasm-like lesions (tumors), and true cysts of the oral tissues and jaws were li sted. Clinical data were reviewed, and microscopic diagnoses were conf irmed for cases in which diagnoses were ambiguous. Records of all case s were examined to identify distant referrals that were not representa tive of the study population. Of a total of 445 (1.11%) odontogenic tu mors, 392 (0.98%) were lesions from patients in the usual local drawin g area of the biopsy service; 53 were referred from distant centers. F rom the local population, odontomas were by far the most common tumor (51.53%) followed by ameloblastomas (13.52%) and peripheral odontogeni c fibromas (8.93%). Locally, radicular (periapical) cysts were the mos t common odontogenic cyst (65.15%) followed by the dentigerous cyst (2 4.08%) and the odontogenic keratocyst (4.88%). The most common nonodon togertic cyst was the nasopalatine duct cyst that accounted for 73.43% of this subset of cysts. Surprisingly few studies of this type are av ailable, especially for odontogenic tumors. These data are important t o assess geographic differences in the incidence of lesions and to all ow clinicians to make realistic judgments in counseling patients befor e biopsy about the probability of diagnosis and risks associated with nonspecific clinical or radiographic lesions.