Correlation in the change of gut microbiota with clinical periodontal parameters in grade C periodontitis patients after non-surgical periodontal therapy

<b>Introduction.</b> Intestinal dysbiosis is associated with systemic health, and approaches targeting the microbiome can influence the host. Oral and intestinal microbiota are interrelated; therefore, we aimed to determine whether non-surgical periodontal treatment (NSPT) affects systemic health through its impact on the intestinal microbiota.<b>Hypothesis/Gap Statement.</b> Although the association between oral and gut microbiota has been suggested, there is limited evidence regarding how periodontal therapy may influence intestinal microbial composition. We hypothesized that NSPT in patients with periodontitis would lead to favourable changes in the gut microbiome, which may parallel improvements in clinical periodontal parameters.<b>Aim.</b> This study aimed to investigate the effect of NSPT on both oral and intestinal microbiota and to evaluate whether changes in gut microbial composition correlate with periodontal clinical outcomes.<b>Methodology.</b> Five systemically healthy individuals with grade C periodontitis and five systemically and periodontally healthy individuals were included. Saliva and stool samples were collected at baseline and 1 month after NSPT. DNA extractions were performed and subjected to 16S ribosomal RNA gene sequencing on the Illumina Novaseq at the V3-V4 hypervariable regions.<b>Results.</b> Grade C periodontitis patients displayed distinct oral and gut microbiomes compared to healthy individuals. NSPT resulted in a reduction in the diversity of both saliva and stool samples in healthy individuals (<i>P</i>>0.05). Salivary <i>Fusobacteriota</i> levels (<i>P</i><0.05) and the gut <i>Firmicutes</i>/<i>Bacteroides</i> ratio decreased after NSPT. Moreover, changes in gut microbiota significantly correlated with improvements in periodontal probing depth and clinical attachment level in periodontitis patients.<b>Conclusion.</b> The improvement in clinical periodontal parameters after NSPT correlates with a positive shift in the gut microbiome towards health. Although the number of participants was limited, these findings support a strong relationship between periodontal and gut status. Further studies with larger cohorts and long-term follow-up are required to confirm these results.