Evaluation of cell proliferation in cystic lesions associated with impacted third molars.

The purpose of this study was to evaluate the metabolism and epithelial cell proliferation of odontogenic keratocyst (OKC), dentigerous cyst (DC), and unicystic ameloblastoma (UA) by quantifying the nucleolar organizing regions (AgNORs) and Ki-67 protein immunoexpression. Forty-eight cases (16 OKC, 16 DC, and 16 UA) were evaluated retrospectively. The metabolism and epithelial cell proliferation was measured by the Ki-67 positive cell percentage index and by the mean AgNOR count in each group. The Ki-67 and AgNOR counts were significantly higher in OKC comparing to the DC and UA (p < .001). Ki-67 positive cells were observed higher in suprabasal cell layers of OKC with uniform distribution, a few of them were predominantly observed in basal cell layer in DC and UA. The AgNOR count was significantly higher in the OKC basal cell layers and observed throughout the lining epithelium of DC and UA. Ki-67 and AgNOR reinforced the aggressive character of OKC, presenting high metabolism and cellular proliferation compared to DC and UA, possibly due to its more aggressive clinical behavior and high recurrence rate. RESEARCH HIGHLIGHTS: We evidence higher metabolism and epithelial cell proliferation in OKC when compared to UA and DC, supporting its aggressive aspect and its high rate of recurrence. OKC had intense and predominant labeling of Ki-67 on the suprabasal layer unlike UA and DC.