New insights into the emerging role of oral spirochaetes in periodontal disease.

Spirochaetes are prominent in the polymicrobial infections that cause periodontal diseases. Periodontitis is a chronic inflammatory condition of the periodontium, characterized by proinflammatory soft tissue damage and alveolar bone loss. Treponema denticola is the most well-understood oral spirochaete, expressing a wealth of virulence factors that mediate tissue penetration and destruction as well as evasion of host immune responses. This review focuses on emerging knowledge of virulence mechanisms of Treponema denticola as well as mechanisms of other less-studied oral treponemes.