Oral Microbiota Features in Subjects with Down Syndrome and Periodontal Diseases: A Systematic Review

Abstract

Down syndrome (DS) is a genetic disorder associated with early-onset periodontitis and other periodontal diseases (PDs). The present work aimed to systematically review the scientific literature reporting studies in vivo on oral microbiota features in subjects with DS and related periodontal health and to highlight any correlation and difference with subjects not affected by DS, with and without PDs. PubMed, Web of Science, Scopus and Cochrane were searched for relevant studies in May 2021. The participants were subjects affected by Down syndrome (DS) with and without periodontal diseases; the study compared subjects with periodontal diseases but not affected by DS, and DS without periodontal diseases; the outcomes were the differences in oral microbiota/periodontopathogen bacterial composition among subjects considered; the study design was a systematic review. Study quality was assessed with risk of bias in non-randomized studies of interventions (ROBINS-I). Of the 954 references retrieved, 26 studies were considered. The conclusions from the qualitative assessment of the papers revealed an increasing knowledge over the last years of the microbiota associated with DS and their periodontal diseases, in comparison with healthy subjects and subjects with other kinds of mental disabilities. Few data have emerged on the mycobiome and virobiome of DS, hence, further investigations are still necessary.

Keywords: Down syndrome; bacteria; dental biofilm; dental plaque; fungi; gingivitis; microbiome; microbiota; periodontal diseases; periodontitis; trisomy 21; virus.

Figure 1

The periodontopathogen potential of each bacterial complex of the supragingival mature plaque and their relationships, according to Haffajee et al., 2008 [46]. The bacteria found in clusters different from the ones of the subgingival plaque are underlined. Actinomyces complex (in blue box) and the yellow complex were tightly associated. The red complex bacteria were associated with both the yellow and orange complexes. The green complex was interrelated with the Actinomyces spp. and the orange complex species. The bacteria in orange square brackets (A. actinomycetemcomitans, P. acnes, and L. buccalis) were occasionally found associated in the yellow complex. Neisseria mucosa and Veillonella parvula of the purple complex were not associated with other complexes, while Treponema socranskii and Gemellia morbillorum related to different clusters and are not shown.

Figure 2

PRISMA 2020 flow diagram.

Figure 3

The most represented phyla, as reported form Segata et al. [48] for subgingival plaque of HC (subP HC), and from Novoa et al. [52], for subgingival plaque of DS, irrespective of periodontal status (subP DS), and in those with (subP P-DS) and without periodontitis (subP H-DS).