Influence of periodontal treatment on subgingival and salivary microbiotas

Background: The purpose of this study was to characterize and compare subgingival and salivary microbiotas before and after periodontal treatment to learn if any changes of the subgingival microbiota were reflected in saliva. We tested the hypothesis that salivary levels of specific periopathogens correlate with corresponding subgingival levels before and after periodontal treatment. Methods: Twenty-five patients with generalized chronic periodontitis completed the study. Stimulated saliva samples and subgingival plaque samples were collected at baseline and 2, 6, and 12 weeks after nonsurgical periodontal therapy. Subgingival and salivary microbiotas were processed by means of the Human Oral Microbe Next Generation Sequencing (HOMINGS) technique and characterized based on relative abundance. Spearman signed rank test was used to test correlation of periopathogens in subgingival and saliva samples. Results: Periodontal treatment resulted in significantly higher relative abundance of Streptococcus, Rothia and Actinomyces in combination with a significant decrease in Porphyromonas and Treponema in subgingival plaque samples. Relative abundance of the overall predominant genera in saliva was not influenced by periodontal treatment. However, there was a positive correlation between samples of subgingival plaque and saliva before and after periodontal treatment (p < 0.0001) with respect to relative abundance of specific periopathogens, such as Porphyromonas gingivalis (r = 0.68), Prevotella intermedia (r = 0.72), Filifactor alocis (r = 0.58), Treponema denticola (r = 0.51), Tannerella forsythia (r = 0.45) and Parvimonas micra (r = 0.45). Conclusions: Subgingival and salivary abundance of periodontal pathogens correlated before and after treatment. Thus, data from this study suggest that periopathogens identified in saliva may be spill-over from the subgingival microbiota.