Saliva microbiome and aging

The salivary microbiome was sampled in patients from a large urban clinic. Age, gender, periodontal status, presence of edentulism, medication, and tobacco usage were recorded for all subjects. Multifactor analysis revealed differences in salivary microbiome profiles were most closely associated with edentulism and, to a lesser degree, tobacco usage and periodontal disease. In the population sampled, there were significantly higher numbers of edentulous subjects and increased levels of polypharmacy with aging. Large differences in alpha diversity and beta diversity of the salivary microbiome in the old age group were largely linked to edentulism. However, multivariable analysis revealed that, even after adjusting for differences in edentulism, polypharmacy, tobacco usage, periodontal disease, and gender, old age itself was associated with higher and lower levels of certain bacteria taxa. Surprisingly, most of these taxa were ones that reside on tooth surfaces. This study indicates that other factors besides tooth loss, polypharmacy, and periodontal disease play a role in the differences seen in oral microbiome with old age.