Objective: The aim of the study was to determine the apoptotic features and proliferation potential of odontogenic keratocysts compared with ameloblastomas and radicular cysts by analysing the role of bax, bcl-2, and Ki-67.

Material and Method: The study material consisted of 20 odontogenic keratocysts, 20 radicular cysts, and 20 ameloblastomas. Immunohistochemically, bax, bcl-2 and Ki-67 were applied. The positive cells were evaluated in both neoplastic/nonneoplastic odontogenic epithelium and connective tissue cells.

Results: Ameloblastoma showed stronger bcl-2 expression than odontogenic keratocysts and radicular cysts. Bcl-2 expression in the whole thickness of epithelium and connective tissue of odontogenic keratocyst was significantly higher than radicular cyst. The expression of bax in the epithelium of radicular cyst was significantly higher than odontogenic keratocyst and ameloblastoma. The lining epithelium of odontogenic keratocyst showed stronger Ki-67 expression than ameloblastoma and radicular cyst.

Conclusion: The proliferation potential of the epithelium and the overexpression of various anti-apoptotic proteins in odontogenic epithelial tumors are quite significant for their clinical behaviour. High expressions of bcl-2 and Ki-67 in odontogenic keratocysts accord with their aggressive clinical behaviour and a high recurrence rate.