Periodontal Microbiome Changes after Intervention

The main outcome variable was the reduction in PPD at 3 and 6 months after intervention, while BOP, CAL, REC, FMPS, FMBS, pocket closure, and detection scores of the five selected bacterial species’ changes (A. actinomycetemcomitans, P. gingivalis, T. forsythia, P. intermedia and T. denticola) were regarded as secondary outcomes. For each of the quantitative variables PPD, REC, CAL, a patient mean value was computed per time point, which was further used in the statistical analyses. Differences between groups for variables measured on a continuous or ordinal scale were analyzed using Kruskal–Wallis tests, with post hoc Mann–Whitney pairwise tests as necessary. Proportions were compared by chi-square tests. Assessment of intragroup differences between successive time points for quantitative variables was performed using Friedman tests, with subsequent Wilcoxon signed-rank tests for pairwise comparisons. The Bonferroni correction was used to account for multiple comparisons. p values < 0.05 were accepted for statistical significance. The statistical analyses were performed using the software R version 4.1.2 [43 ]. Changes in the detection frequency scores of the main keystone bacteria were evaluated in terms of the microbiological status. Results were noted and categorized into one of four groups: 0 = nondetectable, 1 = detectable < 10⁴ (10³ for A.a.), 2 = 10⁴–10⁵ (10³–10⁴ for A.a.), 3 = 10⁵–10⁶ (10⁴–10⁵ for A.a.), and 4 ≥ 10⁷ (10⁶ for A.a.) [42 (link)]. Using the Wilcoxon signed-rank test, intragroup comparisons of detection scores of pathogen species between the baseline and 6-month reevaluation time points were made. For intergroup comparisons of the detection scores at each time point, the Kruskal–Wallis test was applied.