Oxygen sufficiency in the gingiva of smokers and non-smokers with periodontal disease

Background: Epidemiological studies have demonstrated deteriorating effects of smoking on periodontal tissue. The aims of this study were to compare oxygen saturation of hemoglobin in the gingiva (GSo(2)) of smokers and non-smokers and to evaluate the chronic effect of smoking on gingival oxygen sufficiency. Methods: GSo(2) was determined using tissue reflectance spectrophotometry in 110 papillary gingival sites of 62 smokers and 100 sites of 60 non-smokers. Results: No significant difference was found in GSo(2) between smokers and non-smokers. In the model of ANOVA with covariates, age (P = 0.0048) and probing depth (P = 0.0012) had significant effects on GSo(2). No significant effect was found in either smoking status (P = 0.3557) or the modified gingival index (MGI) (P= 0.3824). The interaction effect between smoking status and the MGI was highly significant (P = 0.0003) indicating that the effect of smoking status on the GSo(2) should be compared at each level of the MGI score. GSo(2) in healthy gingiva was significantly lower in smokers than non-smokers (P = 0.0014), while smokers showed higher GSo(2) than non-smokers in moderately inflamed gingiva (P = 0.0356). The GSo(2) in inflamed gingiva was significantly decreased compared with healthy gingiva in non-smokers (P = 0.0044), while smokers showed no significant difference between healthy and inflamed gingiva (P = 0.2772 to 0.8665). GSo(2) in smokers was consistently and significantly lower than that of healthy gingiva of non-smokers (P = 0.0391 to 0.0004). Conclusions: Smokers exhibit possibly lower function of oxygen sufficiency in healthy gingiva and reduced ability to adapt the function in inflamed gingiva than non-smokers. This suggests that smokers have functional impairments in the gingival microcirculation.