Recurrence of the odontogenic keratocyst in relation to clinical and histological features. A 20-year follow-up study of 72 patients.

Seventy-two patients with 75 primary odontogenic keratocysts have been followed from 6 months to 20 years after the primary treatment. Patients with the nevoid basal cell carcinoma syndrome were not included in the material. Fifty-four patients with 57 primary cysts have been followed for 5 years or more, and 18 patients all having a single primary cyst for less. If the number of primary cysts later recurring was related to the number of primary cysts observed for more than 5 years, a recurrence rate of 51% was found. A diagnosis of recurrence was made in 37 cases within a period of 5 years postoperatively and in 10 cases from 5 to 12 years after the operation. Only two of these patients have been followed with regular intervals for the first 5 years postoperatively. The diagnosis of recurrence was in these two cases made 6 and 8 years after the primary treatment. A postoperative follow-up period of 10 years after the last operation is therefore advocated. The occurrence of microcysts and/or islands of odontogneic epithelium in the cyst membrane of 26 nonrecurring cysts, 25 recurring primary cysts and the last recurrence in 14 patients were compared. There were no statistical differences in occurrence of remnants of odontogenic epithelium in the cyst wall between the three groups.