Effects of cigarette smoking on the oral microbiome in adolescents

Smoking, a risk factor for periodontitis and peri-implantitis, is associated with shifts in the oral microbiome (OM) composition. Although smoking habits are almost always established before adulthood, data on effects of smoking on the OM in adolescents is rare. The aim of this study was to investigate the early impact of smoking on the OM composition in pupils. The adolescent cohort, aged 14-20, comprised 98 smokers and 98 non-smokers matched for several physiological co-variates. Buccal swabs were analysed for OM composition using high-throughput sequencing of the full-length 16 S rRNA gene targeting species-level resolution. Parameters of bacterial diversity and abundance of individual bacterial taxa were related to information on smoking. The microbiome dataset contained 733 species-level taxa. Streptococcus, Rothia, and Haemophilus dominated both groups, smokers and non-smokers. Smoking exerted a discernible influence on the overall microbial composition as measured by weighted UniFrac distances. The number of species-level bacterial taxa was significantly higher in individual smokers compared to non-smokers. Furthermore, several taxa, including known pathogens, exhibited significant differences in abundance between the two groups. The genera Veillonella, and Actinomyces, as well as and multiple Actinomyces species, Dialister invisus, Atopobium parvulum, Streptococcus mutans and Prevotella melaninogenica were significantly more abundant in smokers. Our findings indicated an early onset of smoking-related changes already in the oral microbiome of adolescents.