Comparison of Oral Malodor and Microbiome in Smokers and Non-smokers

Objectives: Smoking affects not only systemic conditions, but also the oral environment and may contribute to the onset and/or progression of oral diseases such as periodontal disease. However, the influence of smoking on the oral microbiome has not been clearly determined. The aim of this study was to investigate the influence of smoking on oral malodor and the oral microbiome in smokers and non-smokers.
Methods: The study population consisted of 37 patients with complete data for oral malodor, periodontal examination, and the oral health behavior questionnaire. Volatile sulfur compounds (VSC), which are substances responsible for oral malodor, were measured by gas chromatography. The number of bacteria in saliva and tongue coating was determined by real-time PCR. Mann–Whitney U test, Spearman's correlation coefficient by rank test and multiple linear regression analysis were used to investigate factors affecting the number of bacteria and oral malodor.
Results: The H₂S value of smokers (n=9) was significantly higher than that of non-smokers, including former smokers (n=28) (p<0.05). The mean numbers of total bacteria, Fusobacterium nucleatum and Campylobacter rectus, which are periodontopathogenic bacteria in saliva, were higher in smokers compared with non-smokers (p<0.05). In addition, multiple linear regression analysis showed that smoking influenced the oral microbiome. However, no relationship between the number of each bacterial species and periodontal pocket depth was observed. Bacteria in tongue coatings from 21 patients with no tongue cleaning habit were also investigated. The rates of Fn and Cr per total bacteria in smokers were 3.03% and 0.60%, respectively, approximately 5 times higher than that from non-smokers (p<0.05). The number of Fn and Cr also showed high positive correlation coefficients with all VSC values (p<0.01).
Conclusions: The results of this study suggest that smoking promotes colonization of periodontopathogenic bacteria in tongue coatings and influences oral malodor by increasing the amount of VSC.