JAPANESE JOURNAL OF ORAL & MAXILLOFACIAL SURGERY

Vol. 54 No. 5       2008

ISSN: 0021-5163      UBIC: 151-J

ABSTRACT

The odontogenic keratocyst (OKC) was originally classified as a developmental cyst, and OKCs were histologically divided into orthokeratotic (O-OKCs) and parakeratotic type (P-OKCs). Clinical features differ between O-OKCs and P-OKCs. P-OKCs have a tendency to recur after surgical treatment, as compared with OOKCs. According to the revised histopathological classification of odontogenic tumors by the World Health Organization (2005), the term keratocystic odontogenic tumor (KCOT) was adopted for P-OKCs. In this retrospective study, we examined 186 KCOTs treated at the Maxillofacial Surgery, Tokyo Medical and Dental University Hospital from 1981 through 2005. The patients ranged in age from 7 to 85 years (mean, 32.7) and consisted of 93 males and 93 females. The most frequently involved regions were the mandibular molar region and ramus. The majority of KCOTs in the maxillary region were treated by enucleated and primary closure. The majority of KCOTs in the mandibular region were enucleated, and the wound was left open. Marginal resection was performed in the 4 patients with large lesions arising in the mandible. Recurrences occurred in 19 of 120 lesions (15.8%) in patients who were followed for more than a year. The recurrences were found al the margins of the primary lesion in contact with the roots of teeth or at the upper margins of the mandibular ramus. Clinicians should consider aggressive treatment for KCOT because the recurrence rate of P-OKCs is higher than that of the other cyst types, such as O-OKCs, dentigerous cysts, and primordial cysts that were non-keratinized, and slightly keratinized stratified squamous epithelium. Thus, more aggressive treatment is needed for KCOTs as compared with other cystic lesions. However, it is difficult to make a precise diagnosis preoperatively on the basis of clinical features and X-ray imaging. Therefore, preoperative biopsy is necessary for selecting the appropriate treatment for patients with cystic lesions. Key words: keratocystic odontogenic tumor, odontogenic benign tumor, odontogenic keratocyst, odontogenic orthokeratocyst.

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