Microbial Profiling in Experimentally Induced Biofilm Overgrowth Among Patients With Various Periodontal States.

Background: This study measures microbial composition changes during biofilm overgrowth and subsequent removal among patients with various states of periodontal disease.

Methods: In this prospective cohort study, 175 participants with various periodontal states (five biofilm-gingival interface [BGI] groups) abstained from oral hygiene while using an acrylic stent. At day 21, participants reinstituted oral hygiene and were followed for 4 weeks. Clinical parameters were recorded, and subgingival plaque samples were analyzed at baseline, peak of induction (day 21), and resolution using 16S rRNA probes (human oral microbe identification microarray [HOMIM]). Using the change score (peak at induction minus baseline) for bleeding on probing and probing depth (PD), the patients were separated into high and low clinical responders.

Results: At baseline, synergistetes were more abundant in moderate and severe periodontitis (BGI-P2 and -P3) compared to mild periodontitis (BGI-P1), health (BGI-H), and gingivitis (BGI-G) (P = 0.005). Overall, at day 21 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 resolution, these phyla returned to baseline, except for synergistetes. Levels of synergistetes were significantly higher at day 21 (P ≤0.0001) and resolution (P = 0.0002) for high clinical responders compared to low responders.

Conclusion: The association of synergistetes as a baseline predictor of incident PD increase, as well as the higher levels at day 21, indicates a pathogenic role for these organisms in disease progression in addition to the previously characterized fusobacteria, proteobacteria, firmicutes, and bacteroidetes.