Proliferative activity in periapical lesions.

The identification of proliferative activity in periapical lesions may be useful in discovering the biological behaviour of different cell types. Proliferant cell nuclear antigen (PCNA), Ki67, CD3 and p53 have been used for the evaluation of the proliferative ability of many lesions. In this study, 16 periapical granulomas and 8 radicular cysts were analysed. A semi-quantitative method was used for evaluation of each lesion and antigen. According to the intensity of staining the following scores were assigned: 0 = no reactivity; 1 = reactivity above background; 2 = moderate reactivity; 3 = strong reactivity. Ki67 positive cells were present in all the periapical lesions. The antibody Ki67 was positive in pathological keratinic cells, while it was only slightly positive in normal epithelial cells. PCNA positive cells were present in 22 of the 24 cases examined. CD3 reactivity was also highly positive in periapical lesions. The reaction of oncoprotein p53 in periapical lesions was negative. The expression of the positive reaction of Ki67 and PCNA in periapical lesions is therefore an indicator of cell proliferation as a result of a chronic irritative stimulus.