Method: Prospective cohort study. Participants (five BGI groups) abstained from oral hygiene by using an acrylic stent. At Day 21, participants reinstituted normal oral hygiene and were followed for four weeks. Clinical parameters recorded, and subgingival plaque samples analyzed using 16s probes (HOMIM) at baseline, peak of induction, and resolution.
Result:At baseline, Synergistetes were more abundant in moderate and severe periodontitis (BGI-P2, BGI-P3) compared to mild periodontitis (P1), health (H) and gingivitis (G), p≤0.05). Overall, at the peak of induction there was an increase in HOMIM scores of Firmicutes (p≤0.001), Fusobacteria (p=0.003), Proteobacteria (p≤0.001), Synergistetes (p=0.04), and Bacteroidetes (p≤0.001). At the resolution time point, these phyla returned to baseline, except for Synergistetes. Levels of Synergistetes were significantly higher at baseline (p<0.05), at the peak of induction (p≤0.0001) and at resolution (p=0.0002) for high clinical responders as compared to low responders.
Conclusion: The association of high levels of Synergistetes as a baseline predictor of incident probing depth increase, as well as the higher levels at the peak of induction supports the notion of a pathogenic role for these organisms in disease progression.