Immunohistochemical study of ki-67 and bcl-2 expression in some odontogenic cystic lesions with different clinical behaviors

Background: Cystic lesions with odontogenic epithelial origin and similar clinicoradiographic appearance, show different clinical behaviors. Objective: To compare some factors related to cell proliferation and escape from apoptosis in epithelium covering two groups of odontogenic cystic lesions with different clinical behaviors. Methods: In this cross-sectional study 11 paraffin-embedded samples were selected of each lesions radicular cyst, dentigerous cyst, odontogenic keratocyst, and unicystic ameloblastoma. The sample underwent immunohistochemical staining for investigating the expression of ki-67 antigen and bcl-2 protein. Data analyzed with SPSS17 software and Kruskal–Wallis and chi-square statistical tests. Findings: Most of ki-67 positive cells were observed in parabasal layer of odontogenic keratocyst [35.50±26.29%; P=0.001]. The average of ki-67-LI was more in parabasal layer of aggressive group (26.80±37.79%) compared to non-aggressive group (4.04±3.38%), was not being statistically significant. The highest average of bcl-2-LI was 95±6.70% in basal layer of odontogenic keratocyst (P=0.001). In all layers, the average of bcl-2-LI was more in aggressive lesions compared to non-aggressive ones and the highest amount was found in basal layer (72.45±3.94×10%) which was statistically significant (P=0.001). Conclusion: According to the results of this study, more expression of the markers related to escape from apoptosis in aggressive lesions group compared to non-aggressive group, suggests that escape from apoptosis had a more critical role in aggressive behavior of odontogenic cystic lesions.