Salivary microbiota in periodontal diseases

ABSTRACT The purpose of this study was to examine the compositional changes of the salivary microbiota according to the severity of periodontal disease and to verify whether the distribution of specific bacterial species in saliva can distinguish the severity of disease. Saliva samples were collected from 8 periodontally healthy controls, 16 patients with gingivitis, 19 with moderate periodontitis, and 29 with severe periodontitis. The V3 and V4 regions of the 16S rRNA gene in samples were sequenced and the levels of 9 bacterial species showing significant differences among groups in sequencing analysis were identified using quantitative real-time PCR (qPCR). The predictive performance of each bacterial species to distinguish the severity of disease was evaluated using a receiver operating characteristic curve. The abundance of Bacteroidetes, Fusobacteria, and Spirochaetes increased as the severity of periodontal disease increased, whereas the abundance of Actinobacteria decreased. Twenty-nine species including Porphyromonas gingivalis increased as the severity of disease increased, whereas 6 species including Rothia denticola decreased. The relative abundance of P. gingivalis, Tannerella forsythia, Filifactor alocis, and Prevotella intermedia by qPCR was significantly different among groups. The three bacterial species of P. gingivalis, T. forsythia, and F. alocis were positively correlated with the sum of full mouth probing depth and were moderately accurate at distinguishing the severity of periodontal disease. In conclusion, salivary microbiota showed gradual compositional changes according to severity of periodontitis, and the levels of P. gingivalis, T. forsythia, and F. alocis in mouth rinse saliva had the ability to distinguish severity of periodontal disease.