Association of supragingival plaque management with subgingival microbiota is moderated by adjunctive antibiotics in stage III-IV periodontitis patients during periodontal therapy

Abstract

Background: This study examines the relationship between supragingival plaque control and subgingival microbiota during periodontal therapy, focusing on microbial clusters associated with plaque levels.

Methods: Data were drawn from a 26-month multicenter, double-blinded, randomized, placebo-controlled trial. Supragingival plaque was measured using the O'Leary index, and subgingival microbiota were profiled via Illumina 16S rRNA gene sequencing. A novel topic modelling approach using cross-validated Latent Dirichlet Allocation (LDA) identified microbial clusters, and negative binomial mixed models evaluated their association with plaque levels.

Results: Supragingival plaque was positively associated with bleeding on probing (BOP) and microbial diversity, but not with dysbiosis. A specific subgingival microbial cluster dominated by Selenomonas and Leptotrichia was linked to elevated plaque levels and increased in abundance following both antibiotic and placebo treatments. The odds ratio for plaque associated with this cluster was 1.20 (95% CI: 1.07-1.35). Stratified analyses showed this association was reduced in the antibiotic group but remained in the placebo group.

Conclusion: Ineffective supragingival plaque control correlates with increased BOP and microbial diversity, though not necessarily with dysbiosis. Adjunctive antibiotics may promote a more cariogenic subgingival microbiota by disrupting the association between plaque accumulation and the abundance of acidogenic taxa such as Selenomonas and Leptotrichia.

Keywords: Dental plaque; adjunctive antibiotics; dysbiosis; microbiota; periodontal debridement.

Figure 1.

Workflow of machine learning pipeline. The model workflow incorporates hyperparameter optimization and cross-validation across all steps included in the workflow. Rounded rectangles, diamonds and circles represent raw data inputs, model fitting and fitted models, respectively.

Figure 2.

Univariate associations between microbial and clinical variables and supragingival plaque levels across timepoints. Heatmap displays standardized regression coefficients from univariate regression models, stratified by treatment group (overall, placebo, antibiotic). SMDI was calculated on genus level as described by Chen et al. [33] and dysbiosis topic as previously described [34]. Color intensity reflects the magnitude and direction of the standardized regression coefficients, with significance levels denoted as *p < 0.05, **p < 0.01, and ***p < 0.001.

Figure 3.

Box plots illustrating the percentage of bleeding on probing (%BOP) measured across study visits V2 (baseline) followed by V4 (at 2 months), V6 (at 8 months), V8 at (at 14 months) and V12 (at 26 months after periodontal therapy). Data points are stratified by O’Leary index quantiles.