Figure 1.

The flowchart of subgingival plaque sample collection and comparison of microbiota alpha and beta diversity among the four groups. (a) The sampling strategies of this study. Subgingival plaque samples collected from periodontal healthy subjects were designated as the health group; subgingival plaque samples collected from periodontitis patients from a probing depth of 0–3 mm, 4–5 mm, and 6–9 mm sites were designated as the PD 0–3 mm group, PD 4–5 mm group, and PD 6–9 mm group, respectively. (b) Microbial alpha diversity as calculated by the Chao, Pielou_e, Shannon, and Coverage index. Comparison among groups were calculated by the Kruskal–Wallis test with FDR (false discovery rate); Welch’s (uncorrected) test was used as a post hoc test. (c) The principal coordinates analysis (PCoA) of beta diversity among the four groups was based on the Bray–Curtis and Abund-Jaccard tests. The ellipses indicate 95% confidence intervals for sample groups. (d) The beta diversity difference analysis based on the Bray–Curtis and Abund-Jaccard tests were calculated by the Wilcoxon rank-sum test with FDR. The y-axis represents the beta diversity distance values. * p ≤ 0.05; ** p ≤ 0.01; *** p ≤ 0.001.