Background: This follow‐up study evaluated microbiome changes in periodontal recall patients after consuming a nitrate‐rich diet that led to a marked decrease of gingival inflammation.Methods: Subgingival microbial samples of 37 patients suffering from gingival inflammation with reduced periodontium were taken before professional mechanical plaque removal (baseline) and subsequently after 2 weeks of regularly consuming a lettuce juice beverage (day 14) containing a daily dosage of 200 mg of nitrate (test group, n = 18) or being void of nitrate (placebo group, n = 19). Three hundred base pairs paired‐end sequencing of the V3‒V4 hypervariable region of the 16S rDNA was performed.Results: At baseline, there were no significant differences about the bacterial diversity parameters between the groups (Mann‐Whitney U test). After intervention in the test group, Rothia and Neisseria, including species reducing nitrate, increased significantly (negative binomial regression model). Alpha diversity decreased significantly from 115.69 ± 24.30 to 96.42 ± 24.82 aRSVs/sample (P = 0.04, Wilcoxon signed‐rank test), accompanied by a significant change in beta diversity (P < 0.001, PERMANOVA). In the control group, however, no genus changed significantly, and alpha‐, as well as beta‐diversity did not change significantly.Conclusions: The decrease of gingival inflammation in periodontal recall patients induced by a nitrate‐rich diet is accompanied by significant compositional changes within the subgingival microbiome.

Background: This Consensus Workshop dealt with diagnostic methodologies in the context of surveillance, screening, assessment of stage and grade, prognosis, monitoring and prediction of periodontal status. Several elements provided the impetus for the workshop, including the limited quality of available research on diagnostic tests, the rapid development of new technologies, the implementation of the 2018 classification and the declarations of the World Health Organisation on diagnosis and oral health. Aim: To update and evaluate the evidence on diagnostic methods, considering recent advances in knowledge and the implementation of the 2018 classification. Methods: The European Workshop Committee of the European Federation of Periodontology guided the development of a consensus report after commissioning eight systematic reviews within three working groups. The reviews were discussed during the in‐person consensus meeting involving 70 participants from 21 different countries. Results: Working Group 1 discussed innovations in traditional diagnostic approaches, justified manual probing as the reference standard and assessed the value of image‐based methods. Working Group 2 analysed diagnostic tests based on microbial and host biomarkers and genetic diagnostic tests. Working Group 3 covered emerging technologies to be used within dental and non‐dental clinical settings, focusing principally on the impact of questionnaire‐based assessments and artificial intelligence systems (AIS) in interpreting different data modalities. Conclusion: Although manual periodontal probing is firmly established as the reference standard, additional approaches based on imaging, biomarkers, host genetics, questionnaires and the development of emerging applied data science methods (e.g., AIS) are increasingly integrated in periodontal diagnostics.

Empiric antibiotics are often used in combination with mechanical debridement to treat patients suffering from periodontitis and to eliminate disease-associated pathogens. Until now, only a few next generation sequencing 16S rDNA amplicon based publications with rather small sample sizes studied the effect of those interventions on the subgingival microbiome. Therefore, we studied subgingival samples of 89 patients with chronic periodontitis (solely non-smokers) before and two months after therapy. Forty-seven patients received mechanical periodontal therapy only, whereas 42 patients additionally received oral administered amoxicillin plus metronidazole (500 and 400 mg, respectively; 3x/day for 7 days). Samples were sequenced with Illumina MiSeq 300 base pairs paired end technology (V3 and V4 hypervariable regions of the 16S rDNA). Inter-group differences before and after therapy of clinical variables (percentage of sites with pocket depth ≥ 5mm, percentage of sites with bleeding on probing) and microbiome variables (diversity, richness, evenness, and dissimilarity) were calculated, a principal coordinate analysis (PCoA) was conducted, and differential abundance of agglomerated ribosomal sequence variants (aRSVs) classified on genus level was calculated using a negative binomial regression model. We found statistically noticeable decreased richness, and increased dissimilarity in the antibiotic, but not in the placebo group after therapy. The PCoA revealed a clear compositional separation of microbiomes after therapy in the antibiotic group, which could not be seen in the group receiving mechanical therapy only. This difference was even more pronounced on aRSV level. Here, adjunctive antibiotics were able to induce a microbiome shift by statistically noticeably reducing aRSVs belonging to genera containing disease-associated species, e.g., Porphyromonas, Tannerella, Treponema, and Aggregatibacter, and by noticeably increasing genera containing health-associated species. Mechanical therapy alone did not statistically noticeably affect any disease-associated taxa. Despite the difference in microbiome modulation both therapies improved the tested clinical parameters after two months. These results cast doubt on the relevance of the elimination and/or reduction of disease-associated taxa as a main goal of periodontal therapy.

Aim: To explore whether adjunctive antibiotics can relevantly influence long‐term microbiota changes in stage III–IV periodontitis patients.Materials and Methods: This is a secondary analysis of a randomized clinical trial on periodontal therapy with adjunctive 500 mg amoxicillin and 400 mg metronidazole or placebo thrice daily for 7 days. Subgingival plaque samples were taken before and 2, 8, 14 and 26 months after mechanical therapy. The V4‐hypervariable region of the 16S rRNA gene was sequenced with Illumina MiSeq 250 base pair paired‐end reads. Changes at the ribosomal sequence variant (RSV) level, diversity and subgingival‐microbial dysbiosis index (SMDI) were explored with a negative binomial regression model and non‐parametric tests.Results: Overall, 50.2% of all raw reads summed up to 72 RSVs (3.0%) that were generated from 163 stage III–IV periodontitis patients. Of those, 16 RSVs, including Porphyromonas gingivalis, Tannerella forsythia and Aggregatibacter actinomycetemcomitans, changed significantly over 26 months because of adjunctive systemic antibiotics. SMDI decreased significantly more in the antibiotic group at all timepoints, whereas the 2‐month differences in alpha and beta diversity between groups were not significant at 8 and 14 months, respectively.Conclusions: Mechanical periodontal therapy with adjunctive antibiotics induced a relevant and long‐term sustainable change towards an oral microbiome more associated with oral health.

Aim: This subgroup analysis of a 12‐week randomized, double‐blind, and two‐center trial aimed to evaluate whether two different toothpaste formulations can differentially modulate the dental microbiome.Material and Methods: Forty one mild to moderate periodontitis patients used as an adjunct to periodontal treatment either a toothpaste with anti‐adhesive zinc‐substituted carbonated hydroxyapatite (HA) or with antimicrobial and anti‐adhesive amine fluoride/stannous fluoride (AmF/SnF₂) during a 12‐week period. Plaque samples from buccal/lingual, interproximal, and subgingival sites were taken at baseline, 4 weeks after oral hygiene phase, and 8 weeks after periodontal therapy. Samples were analyzed with paired‐end Illumina Miseq 16SrDNAsequencing. The differences and changes on community level (alpha and beta diversity) and on the level of single agglomerated ribosomal sequence variants (aRSV) were calculated with analysis of covariance (ANCOVA) and likelihood ratio test (LRT).Results: Interproximal and subgingival sites harbored predominatelyFusobacteriumandPrevotellaspecies associated with periodontitis, whereas buccal/lingual sites harbored mainlyStreptococcusandVeillonellaspecies associated with periodontal health. Alpha and beta diversity did not change noticeably differently between both toothpaste groups (P > 0.05,ANCOVA). Furthermore, none of theaRSVs showed a noticeably different change between the tested toothpastes during periodontal therapy (P_adj .> 0.05,LRT).Conclusion: The use of a toothpaste containing anti‐adhesiveHAdid not induce statistically noticeably different changes on microbial composition compared to an antimicrobial and anti‐adhesive AmF/SnF₂formulation.

Background: Periodontitis, a prevalent chronic inflammatory disease, offers insights into the broader landscape of chronic inflammatory conditions. The progression and treatment outcomes of periodontitis are closely related to the oral microbiota’s composition. Adjunctive systemic Amoxicillin 500 mg and Metronidazole 400 mg, often prescribed thrice daily for 7 days to enhance periodontal therapy’s efficacy, have lasting effects on the oral microbiome. However, the precise mechanism through which the oral microbiome influences clinical outcomes in periodontitis patients remains debated. This investigation explores the pivotal role of the oral microbiome's composition in mediating the outcomes of adjunctive systemic antibiotic treatment. Methods: Subgingival plaque samples from 10 periodontally healthy and 163 periodontitis patients from a randomized clinical trial on periodontal therapy were analyzed. Patients received either adjunctive amoxicillin/metronidazole or a placebo after mechanical periodontal treatment. Microbial samples were collected at various intervals up to 26 months post-therapy. Using topic models, we identified microbial communities associated with normobiotic and dysbiotic states, validated with 86 external and 40 internal samples. Logistic regression models evaluated the association between these microbial communities and clinical periodontitis parameters. A Directed Acyclic Graph (DAG) determined the mediating role of oral microbiota in the causal path of antibiotic treatment effects on clinical outcomes. Results: We identified clear distinctions between dysbiotic and normobiotic microbial communities, differentiating healthy from periodontitis subjects. Dysbiotic states consistently associated with below median %Pocket Probing Depth ≥ 5 mm (OR = 1.26, 95% CI [1.14–1.42]) and %Bleeding on Probing (OR = 1.09, 95% CI [1.00–1.18]). Factors like microbial response to treatment, smoking, and age were predictors of clinical attachment loss progression, whereas sex and antibiotic treatment were not. Further, we showed that the oral microbial treatment response plays a crucial role in the causal effect of antibiotic treatment on clinical treatment outcomes. Conclusions: The shift towards a normobiotic subgingival microbiome, primarily induced by adjunctive antibiotics, underscores the potential for microbiome-targeted interventions to enhance therapeutic efficacy in chronic inflammatory conditions. This study reaffirms the importance of understanding the oral microbiome's role in periodontal health and paves the way for future research exploring personalized treatment strategies based on individual microbiome profiles.