Red Complex Bacteria’s Role in Periodontitis
Periodontitis is caused by layers of bacteria called microbial plaque, or dental biofilms, that adhere to and grow on tooth surfaces, particularly in areas below the gum line. Specific bacteria called red complex bacteria (RCB) are strongly associated with periodontal infection. The RCB are: P gingivalis, T denticola, and T forsythia.
- Red complex baterica (RCB) are more prevalent in patients with periodontal disease
- A direct association exists between an unhealthy balance of RCB and increased pocket depth (PD), clinical attachment loss (CAL), and bleeding on probing (BOP)
Clinical signs of RCB and periodontal infection include inflammation and bleeding on probing.
Hear Dr. Sigmund Socransky, an expert from Forsythe University, explain the sequential development of bacteria species in the oral cavity, and the unhealthy balance seen in active periodontitis.
In a healthier mouth there is a high ratio of actinomyces bacteria (pink, in the top chart) to RCB. In periodontitis, there is more red complex bacteria than actinomyces.
Why isn't scaling and root planing enough to eliminate periodontitis? Learn about the need for more comprehensive periodontitis treatment.

