Immunoexpression of Interleukin 17, 6, and 1 Beta in Primary Chronic Apical Periodontitis in Smokers and Nonsmokers

The purpose of this study was to compare the immunoexpression of biomarkers interleukin (IL)-17, IL-6, and IL-1β in primary chronic apical periodontitis in smokers and nonsmokers. Teeth with primary chronic apical periodontitis indicated for extraction in 16 cigarette smokers and 16 nonsmokers were selected. Silanized sections of tissue were used for immunohistochemical analysis after being stained with hematoxylin-eosin for histopathologic categorization. Subsequently, the images were analyzed with an optical microscope, and each slide was subdivided into 5 high-magnification fields, with scores (0–2) being assigned according to the amount of staining for each antibody. The qualitative analysis of IL-17 cytokine expression showed no focal expression in 5.8%, weak to moderate expression in 17.6%, and strong expression in 76.4% of the smokers and no focal expression in 78.5% and weak to moderate expression in 21.4% of the nonsmokers. IL-6 expression was negative to focal in 13.3%, weak to moderate in 53.3%, and strong in 33.3% of the smokers and negative to focal in 33.3%, weak to moderate in 25%, and strong in 41.6% of the nonsmokers. IL-1β expression was weak to moderate in 87.5% and negative to focal expression in 12.5% of the smokers and negative to focal expression in 100% of the nonsmokers. Quantitative evaluation of the data using the Mann-Whitney U test showed a significant difference in the immunoexpression of IL-17 (P < .0001) and IL-1β (P < .0001) and no significant difference in the immunoexpression of IL-6 (P = .46) between the 2 groups (P < .05). The cytokines IL-17 and IL-1β were more highly expressed in smokers than nonsmokers, whereas IL-6 expression was similar in the 2 groups.