Oral microbiology

See also: Oral Ecology See also: Oral Ecology Oral microbiology is the study of the microorganisms (microbiota) of the oral cavity and their interactions between oral microorganisms or with the host. The environment present in the human mouth is suited to the growth of characteristic microorganisms found there. It provides a source of water and nutrients, as well as a moderate temperature. Resident microbes of the mouth adhere to the teeth and gums to resist mechanical flushing from the mouth to stomach where acid-sensitive microbes are destroyed by hydrochloric acid. Anaerobic bacteria in the oral cavity include: Actinomyces, Arachnia, Bacteroides, Bifidobacterium, Eubacterium, Fusobacterium, Lactobacillus, Leptotrichia, Peptococcus, Peptostreptococcus, Propionibacterium, Selenomonas, Treponema, and Veillonella. Genera of fungi that are frequently found in the mouth include Candida, Cladosporium, Aspergillus, Fusarium, Glomus, Alternaria, Penicillium, and Cryptococcus, among others. Bacteria accumulate on both the hard and soft oral tissues in biofilms. Bacterial adhesion is particularly important for oral bacteria. Oral bacteria have evolved mechanisms to sense their environment and evade or modify the host. Bacteria occupy the ecological niche provided by both the tooth surface and gingival epithelium. However, a highly efficient innate host defense system constantly monitors the bacterial colonization and prevents bacterial invasion of local tissues. A dynamic equilibrium exists between dental plaque bacteria and the innate host defense system. Of particular interest is the role of oral microorganisms in the two major dental diseases: dental caries and periodontal disease. Additionally, research has correlated poor oral heath and the resulting ability of the oral microbiota to invade the body to affect cardiac health as well as cognitive function. The oral microbiome, mainly comprising bacteria which have developed resistance to the human immune system, has been known to impact the host for its own benefit, as seen with dental cavities. The environment present in the human mouth allows the growth of characteristic microorganisms found there. It provides a source of water and nutrients, as well as a moderate temperature. Resident microbes of the mouth adhere to the teeth and gums to resist mechanical flushing from the mouth to stomach where acid-sensitive microbes are destroyed by hydrochloric acid. Anaerobic bacteria in the oral cavity include: Actinomyces, Arachnia, Bacteroides, Bifidobacterium, Eubacterium, Fusobacterium, Lactobacillus, Leptotrichia, Peptococcus, Peptostreptococcus, Propionibacterium, Selenomonas, Treponema, and Veillonella. In addition, there are also a number of fungi found in the oral cavity, including: Candida, Cladosporium, Aspergillus, Fusarium, Glomus, Alternaria, Penicillium, and Cryptococcus. The oral cavity of a new-born baby does not contain bacteria but rapidly becomes colonized with bacteria such as Streptococcus salivarius. With the appearance of the teeth during the first year colonization by Streptococcus mutans and Streptococcus sanguinis occurs as these organisms colonise the dental surface and gingiva. Other strains of streptococci adhere strongly to the gums and cheeks but not to the teeth. The gingival crevice area (supporting structures of the teeth) provides a habitat for a variety of anaerobic species. Bacteroides and spirochetes colonize the mouth around puberty. Of particular interest is the role of oral microorganisms in the two major dental diseases: dental caries and periodontal disease. The habitat of the oral microbiome is essentially the surfaces of the inside of the mouth. Saliva plays a considerable role in influencing the oral microbiome. More than 800 species of bacteria colonize oral mucous, 1,300 species are found in the gingival crevice, and nearly 1,000 species comprise dental plaque. The mouth is a rich environment for hundreds of species of bacteria since saliva is mostly water and plenty of nutrients pass through the mouth each day. When kissing, it takes only 10 seconds for no less than 80 million bacteria to be exchanged by the passing of saliva. However, the effect is transitory, as each individual quickly returns to their own equilibrium. Thanks to progress in molecular biology techniques, scientific understanding of oral ecology is improving. Oral ecology is being more comprehensively mapped, including the tongue, the teeth, the gums, salivary glands, etc. which are home to these communities of different microorganisms. The host’s immune system controls the bacterial colonization of the mouth and prevents local infection of tissues. A dynamic equilibrium exists notably between the bacteria of dental plaque and the host’s immune system, enabling the plaque to stay behind in the mouth when other biofilms are washed away.