Tannerella forsythia is a bacterium that is known to cause periodontal disease, a bacterial infection that affects the gums and bone supporting the teeth. It is also referred to as Bacteroides forsythus, Porphyromonas gingivalis, and Tanerella forsythensis. Though the final classification of the bacterium is still controversial, it is widely acknowledged for its role in the development of periodontitis. Its most common synonyms include P. gingivalis, T. forsythensis, B. forsythus, and F. forsythia, among others. The identification and treatment of periodontal disease can prevent severe damage to oral health, including tooth loss. Regular brushing, flossing, and professional cleaning also help prevent the infection.