Subgingival dysbiosis in smoker and non-smoker patients with chronic periodontitis

Periodontitis is one of the most common oral inflammatory diseases resulting in degradation of connective tissue with a gradual tooth loss. It manifests in formation of a periodontal pockets, in which anaerobic and Gram-negative bacteria proliferate rapidly. Consequently, an alteration of subgingival microbiota is considered the primary etiologic agent of periodontitis. Furthermore, it has been reported that smoker subjects have an increased in prevalence and severity of periodontal disease, addressing smoking as a risk factor for the onset and progression of the pathology. In our study, we used 16S rRNA sequencing to assess the subgingival microbiota in 6 smoker patients with chronic periodontal disease, 6 non-smoker patients with chronic periodontitis and 8 healthy controls, confirming a significantly altered microbial structure in periodontitis patients. With a metagenomics analysis, we identified high relative abundance of Parvimonans, Desulfubulbus, Paludibacter, Haemophilus, and Sphaerochaeta in periodontitis patients, investigating their role in periodontal disease. Thanks to the depth and the high degree of precision of our analysis, we focalized our attention also on the low-abundance of some bacterial genera like Pedobacter, Granulicatella, Paracoccus, Atopobium, Bifidobacterium, Coprococcus, Oridobacterium, Peptococcus, Oscillospira, Akkermansia in periodontitis associated microbiota. Interestingly, in these analyses smoker patients evidenced a major microbial community alteration. Definitely, our study reveals novel key phylotypes probably associated with periodontitis. Moreover, we confirm that chronic periodontitis may be considered a polymicrobial dysbiosis where changes in the equilibrium of subgingival microbiota contribute to severity of pathology.