A systematic review on the expression of bcl-2 in the nonsyndromic odontogenic keratocyst: should it be considered a cyst or a tumor?

The purpose of this study is to find out if the biological behavior and the capacity of the odontogenic keratocyst (OKC) in maintaining pathologic cells alive are more similar to the dentigerous cyst or to the ameloblastoma by assessing bcl-2. We searched MEDLINE, Web of Science, and Scopus for immunohistochemical studies reporting OKCs, dentigerous cysts, and ameloblastomas. Risk difference between the lesions expressing bcl-2 was the effect measure and a P value < 0.05 was considered to provide evidence to the effect estimates. OKCs have an estimated difference of 91% in the probability to express the bcl-2 over dentigerous cysts, but there is no difference in the expression of bcl-2 between OKCs and ameloblastomas. The present study demonstrated a great risk difference in the expression of bcl-2 between OKCs and dentigerous cysts and no risk difference between OKCs and ameloblastomas. OKC's growth may indirectly be attributed to the anti-apoptotic effect of bcl-2 in the cystic epithelium and not only to the increase of its intraluminal pressure. Therefore, the classification of this lesion into keratocystic odontogenic tumor should be carefully reconsidered.