Overview: The genus Porphyromonas is abundant in the healthy mouth, making up between 2% and 5% of the community at each site within the mouth (Segata et al. 2012).

Ecological role/importance in health and disease: Among the 12 oral species, P. pasteri has the broadest distribution, making up 1-4% of the total community at each oral site (Eren et al. 2014). The unnamed Porphyromonas sp. HMT 930 dominates on the keratinized gingiva and is also abundant on the buccal mucosa. The widely studied taxa P. gingivalis and P. endodontalis are detected with low abundance in subgingival plaque in healthy individuals but become more prominent in periodontitis. P. gingivalis, together with Treponema denticola and Tannerella forsythia, is part of the "red complex" of subgingival taxa associated with periodontitis (Socransky et al. 1998).