Background: Ki-67 which is a non-histone nuclear protein which is expressed in proliferating cells, during all the active phases of the cell cycle. Increased Ki-67 expression has been seen in several inflammatory and malignant conditions like diabetes, rheumatoid arthritis, atherosclerosis, pancreatitis and squamous cell carcinoma.
Aim: The aim of the present study is to analyze the expression of Ki-67 in gingival tissues by immunohistochemistry in smokers and non-smokers with healthy gingiva and chronic periodontitis.
Materials and methods: Gingival biopsies (n = 32) were obtained from smokers who had clinically healthy gingiva (n = 8), smokers with periodontitis (n = 8), chronic periodontitis (n = 8) and healthy gingiva (n = 8). The expression of Ki-67 was evaluated immunohistochemically.
Statistical analysis used: Mean and standard deviation were estimated for the gingival tissue extract sample for each study group. Mean values were compared between different study groups by, one way ANOVA, post hoc analysis. In this study P < 0.05 was considered as the level of significance.
Results: The mean number of Ki-67 positive cells/field was higher in the smokers with periodontitis group. When the mean Ki-67 positive cells were compared between different groups, statistical significant difference was observed between healthy and both the periodontitis groups (P = 0.000) and between smokers group (P = 0.001).
Conclusions: Ki-67 was maximally expressed in smoker with periodontitis followed by chronic periodontitis patients, healthy smokers and healthy control patients which shed light on the toxic effects of tobacco in dysregulating the cell cycle and cellular proliferation. The findings of this study also help us to understand the role of the cell cycle in resolution of periodontal inflammation which is a salient feature in the pathogenesis of chronic periodontitis.
Keywords: Chronic periodontitis; Ki-67; smoking.