Evaluation of bax and bcl-2 expression in odontogenic keratocysts and orthokeratinized odontogenic cysts: A comparison of two cysts.

Odontogenic keratocyst (OKC) has an aggressive clinical course and a high tendency toward recurrence, while orthokeratinized odontogenic cyst has different characteristics and does not show aggressive behavior. Bax and bcl-2 are two important anti-apoptotic and pro-apoptotic factors of the bcl-2 family. The different outcomes of theses two cysts could be related to these apopto-proteins. Twenty-eight cases of OKC and nine cases of orthokeratinized odontogenic cyst (OOC) were stained for bax and bcl-2 proteins. Immunoreactivity for bcl-2 was detected in the basal layer of OKCs, while OOCs were completely negative in the basal layer (P<0.001). Bcl-2 expression in the whole thickness of OKCs was also significantly higher than in OOCs (P<0.001). Bax expression did not show any statistically significant difference between the two cysts (P=0.077). The different behaviors of these cysts are compatible with their immunohistochemical view. Lower expression of bcl-2 in OOC ends in less aggressiveness and a lower tendency toward recurrence. Bax seems to play no significant role by itself; however, the bcl-2/bax ratio is probably a determinant factor for different outcomes.