The Oral Microbiome in Periodontal Health.

Magdalena Lenartova,Lucie Najmanova,Tatjana Janatova,Ondrej Hrebicek,Jaroslav Mysak,Jiri Janata,Barbora Tesinska

doi:10.3389/fcimb.2021.629723

Abstract

The estimation of oral microbiome (OM) taxonomic composition in periodontally healthy individuals can often be biased because the clinically periodontally healthy subjects for evaluation can already experience dysbiosis. Usually, they are included just based on the absence of clinical signs of periodontitis. Additionally, the age of subjects is used to be higher to correspond well with tested groups of patients with chronic periodontitis, a disorder typically associated with aging. However, the dysbiosis of the OM precedes the clinical signs of the disease by many months or even years. The absence of periodontal pockets thus does not necessarily mean also good periodontal health and the obtained image of “healthy OM” can be distorted.To overcome this bias, we taxonomically characterized the OM in almost a hundred young students of dentistry with precise oral hygiene and no signs of periodontal disease. We compared the results with the OM composition of older periodontally healthy individuals and also a group of patients with severe periodontitis (aggressive periodontitis according to former classification system). The clustering analysis revealed not only two compact clearly separated clusters corresponding to each state of health, but also a group of samples forming an overlap between both well-pronounced states. Additionally, in the cluster of periodontally healthy samples, few outliers with atypical OM and two major stomatotypes could be distinguished, differing in the prevalence and relative abundance of two main bacterial genera: Streptococcus and Veillonella. We hypothesize that the two stomatotypes could represent the microbial succession from periodontal health to starting dysbiosis. The old and young periodontally healthy subjects do not cluster separately but a trend of the OM in older subjects to periodontitis is visible. Several bacterial genera were identified to be typically more abundant in older periodontally healthy subjects.

Highlights

Periodontitis is the sixth most common disease worldwide (Frencken et al, 2017)
The HO and AP subjects were obtained within the study approved by the Ethics Committee of the First Faculty of Medicine of Charles University and General University Hospital in Prague as a part of project No 17-30753A of the Czech Health Research Council and besides periodontitis in the AP group, they were of good general health, the sampling of HY subjects was approved within a project No 486417 from the Grant Agency of Charles University
The rarefaction curves were calculated for a random selection of 1000 sequences to reflect the minimum sample size, set up to cover the expected relevant taxonomic diversity of oral microbiome samples

Summary

Introduction

Periodontitis is the sixth most common disease worldwide (Frencken et al, 2017). The major forms of periodontal disease are gingivitis, chronic periodontitis (which can be the result of untreated gingivitis) and according to former classification aggressive periodontitis, which differs from the chronic variant by faster and more extensive disease progression, lower age of patients, and obvious familial aggregation (Armitage and Cullinan, 2010; Van der Velden, 2017). Periodontal disease poses a set of inflammatory conditions affecting the tissues surrounding the teeth It spreads from the gingiva into the deeper, supportive components of the periodontium: the gum, connective tissue, and the alveolar bone surrounding and supporting a tooth (Hernández et al, 2011), and in more severe cases it can lead to a tooth loss (Kirst et al, 2015). It is a complex infectious disease, where specific pathogenic bacteria growing in biofilms play a key role. It is the result of the interplay between subgingival biofilm and host immune response and is further affected by other local, environmental, and genetic factors (Griffen et al, 2012)

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