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

ABSTRACT Aim To examine the association between the oral microbiome, periodontitis, and edentulism in a nationally representative sample of the U.S. population. 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.