Oral Microbiome Signatures in Periodontitis and Edentulism—A Population‐Based Study

AIM: To examine the association between the oral microbiome, periodontitis, and edentulism in a nationally representative sample of the U.S. METHODS: A total of 5299 adults aged 30-69 years were examined (NHANES 2009-2012). Oral rinse samples were collected and analyzed through 16S rRNA gene sequencing. Periodontitis presence, stage, extent, and grade were assessed according to the 2017 AAP/EFP classification using the ACES framework, with edentulism considered as a distinct category. Bacterial diversity and taxonomic composition were evaluated using alpha and beta diversity metrics and multivariable linear models (MaAsLin2), adjusted for relevant confounders. RESULTS: Alpha diversity increased with periodontitis severity, extent, and grade, peaking in Stage III generalized periodontitis. In Stage IV, extensive tooth loss was associated with a decrease in alpha diversity. Edentulous individuals exhibited the lowest alpha diversity, falling below levels observed in those without periodontitis. Beta diversity differences across periodontitis severity, extent, and grade were subtle (< 0.2%). Taxonomically, increasing severity, extent, and grade of periodontitis were associated with enrichment of established periodontitis-related genera (e.g., Dialister, Filifactor, Fusobacterium, Porphyromonas, Prevotella, Tannerella) and Jonquetella, alongside depletion of health-related genera (e.g., Rothia, Veillonella). A total of 13 genera were commonly altered in both edentulous individuals and those with Stage III-IV periodontitis, relative to participants with no or localized Stage I-II disease. CONCLUSION: Periodontitis is characterized by an increase in alpha diversity with advancing severity, extent, and grade, followed by a decline with extensive tooth loss and edentulism. However, it accounted for only a small fraction of the overall variation in oral microbiome composition. Taxonomic shifts included enrichment of established periodontitis-related genera and Jonquetella, alongside depletion of health-related genera. The persistence of periodontitis-associated bacteria in edentulous individuals may have important implications for implant dentistry.