Definition:

During the early stages of the periodontal disease, saccharolytic, aerobic Streptococcus spp. and other bacteria adhere to and colonize the tooth enamel and root surface. This sets the stage for Fusobacterium nucleatum to coaggregate with these early colonizers and to permit late colonizers, including dental pathogens, to eventually form a biofilm. These complex interactions result in the release of factors that lead to tooth decay. Physical interaction is very specific among various genera in this complex microbial community. Due to the unusual length, adhesive nature, and other cell surface properties of F. nucleatum, periodontal disease-causing bacteria such as Porphyromonas gingivalis, Bacteroides forsythus, Aggregatibacter actinomycetemcomitans, Treponema denticola, and Streptococcus spp. aggregate and thrive; hence, F. nucleatum is thought of as a 'bridge bacterium'.