Anaerobes as normal oral flora.

The human mouth provides a suitable habitat for numerous bacterial genera. Anaerobic genera or genera that include anaerobic members found in the oral cavity are Actinomyces, Arachnia, Bacteroides, Bifidobacterium, Eubacterium, Fusobacterium, Lactobacillus, Leptotrichia, Peptococcus, Peptostreptococcus, Propionibacterium, Selenomonas, Treponema, and Veillonella. The incidence of anaerobes varies with age of the individual and with specific sites sampled. In edentulous infants, the incidence of anaerobes is relatively low. In adults, anaerobes are invariably present but are more prevalent in samples from the gingival sulcus than they are in samples from the gingival margin, tooth surfaces, buccal mucosa, tongue, or saliva. In samples from the healthy gingival sulcus, anaerobic, gram-positive bacilli are found in the range of 5%-14%; gram-negative bacilli in the range of 13%-29%; Veillonella in the range of 2%-8%; and gram-positive cocci in the range of 1%-15% of the cultivable flora. From marginal plaque and plaque from the tooth surface, gram-positive bacilli, gram-positive cocci, and Veillonella appear to be the predominant anaerobes. In saliva, Veillonella are the most numerous anaerobes.