The red complex is a group of

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...

that are categorized together based on their association with severe forms of

periodontal disease Periodontal disease, also known as gum disease, is a set of inflammatory conditions affecting the tissues surrounding the teeth. In its early stage, called gingivitis, the gums become swollen and red and may bleed. It is considered the main caus ...

. The red complex—among a number of other

complex Complex commonly refers to: * Complexity, the behaviour of a system whose components interact in multiple ways so possible interactions are difficult to describe ** Complex system, a system composed of many components which may interact with each ...

es—were classified by Sigmund Socransky in 1998. The three members of the red complex are: # ''

Porphyromonas gingivalis ''Porphyromonas gingivalis'' belongs to the phylum ''Bacteroidota'' and is a nonmotile, Gram-negative, rod-shaped, anaerobic, pathogenic bacterium. It forms black colonies on blood agar. It is found in the oral cavity, where it is implicate ...

'' # '' Tannerella forsythia'' # ''

Treponema denticola ''Treponema denticola'' is a Gram-negative, obligate anaerobic, motile and highly proteolytic spirochete bacterium. It is one of four species of oral spirochetes to be reliably cultured, the others being ''Treponema pectinovorum, Treponema socra ...

References

{{dentistry-stub Periodontology