Abstract: Objective By comparing the histopathological characteristics of gingiva taken from untreated smoking and non-smoking patients with advanced periodontitis, to investigate the possible role of smoking in the genesis and development of periodontitis.Methods The gingival biopsies of untreated smoking and non-smoking advanced patients with periodontitis were performed, and routine histopathological and immunohistochemical methods were used to assess the general histological characteristics and the changes of gingival blood vessel density and circumference respectively.Results Compared with non-smokers, the hyperplasia of pocket epithelium in smokers was continuously extending toward root apex, and the layer of keratin is thicker. The difference between the vascular density of smokers and non-smokers was not significant, however, smokers showed a higher proportion of small and a lower proportion of large blood vessels.Conclusion These results indicated that smoking maybe deepen the pocket and disturb the reattachment of periodontal tissue by prompting the hyperplasia and keratinization of pocket epithelium. The incremental proportion of small vessels proportion maybe result in a decline of the total blood flow in gingiva, which may in turn impair the resistibility and restoration of tissue.

Key words: smoking, periodontitis, epithelium, vessel