Odontogenic keratocysts: a clinical and histologic comparison of the parakeratin and orthokeratin variants.

Four hundred forty-nine cases of odontogenic keratocyst (OKC) were separated into three histologic categories: parakeratinized, orthokeratinized, or a combination of the two types. Demographic and clinical data, such as anatomic location and recurrence, were obtained from the biopsy forms. Results showed that 86.2% of the 449 cases were parakeratinized, 12.2% were orthokeratinized, and 1.6% had features of both orthokeratin and parakeratin. There were no statistically significant differences between orthokeratinized and parakeratinized OKCs when age, race, sex, presenting symptoms, and the clinical impression were compared. The orthokeratinized OKC was more often associated with an impacted tooth (75.7%), as compared with 47.8% for the parakeratinized OKC (P = .001). Parakeratinized OKCs recurred in at least 42.6% of the cases, compared with only 2.2% for orthokeratinized OKCs. This study emphasizes the importance of distinguishing between the parakeratin and orthokeratin variants of OKC. In addition, data are presented that show the need for longer follow-up than previously documented.