User:BostonBiologyM/sandbox

Issues and Areas of Research
The oral environment (temperature, humidity, pH, nutrients, etc.) impacts the selection of adapted (and sometimes pathogenic) populations of microorganisms.

For a young person or an adult in good health and with a healthy diet, the microbes living in the mouth adhere to mucous, teeth and gums to resist removal by saliva. Eventually, they are mostly washed away and destroyed during their trip through the stomach.

Salivary flow and oral conditions vary person-to-person, and also relative to the time of day and whether or not an individual sleeps with their mouth open. From youth to old age, the entire mouth interacts with and affects the oral microbiome.

Via the larynx, numerous bacteria can travel through the respiratory tract to the lungs. There, mucous is charged with their removal.

Pathogenic oral microflora have been linked to the production of factors which favor autoimmune diseases such as psoriasis and arthritis, as well as cancers of the colon, lungs and breasts.

Niche
The habitat of the oral microbiome comprises the surfaces of the inside of the mouth. Saliva, made mostly of water, plays a considerable role in influencing the oral microbiome. More than 800 species of bacteria colonize oral mucous, 1,300 are found in the gingival crevice, and nearly 1,000 comprise dental plaque, an extremely tough biofilm resistant to the flow of saliva. Saliva is a rich environment for hundreds of species of bacteria, of which the concentration ranges from 10 cells per milliliter to billions of cells per milliliter. When kissing, it takes only 10 seconds for no less than 80 million bacteria to be exchanged by the passing of saliva, but the effect is transitory, as each individual quickly returns their salivary microbiota to equilibrium.

Thanks to progress in tools to analyze molecular biology, this environment and more generally the territories drawn in the mouth by oral ecology are starting to be better mapped (such as the top and sides of the tongue) the teeth, the gums, inside the jaws, salivary glands, etc. which are home in effect to these communities or consortiums of different microorganisms.

The host has a very effective defense mechanism, whereby the immune system controls bacterial colonization and prevents local infection of tissues. A dynamic equilibrium exists most notably between the bacteria of dental plaque and the host’s immune system.

In equilibrium, the bacterial biofilm produced by the fermentation of sugar in the mouth is quickly swept away by the saliva, except for dental plaque. In cases of imbalance in the equilibrium, oral microorganisms grow out of control and cause oral diseases such as tooth decay and periodontal disease. Several studies have also linked poor oral hygiene to infection by pathogenic bacteria.

Microflora
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. Microbes residing in the mouth may be bacterial or fungal.

Oral microorganisms can accumulate on (or in) the hard and soft tissues of the mouth, forming biofilms which are oftentimes washed away by saliva. Oral biofilms are suspected of contributing to antibiotic resistance.

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.

oral cavity of the 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.

Health Effects
There are many factors of oral health which need to be preserved in order to prevent pathogenesis of the oral microbiome or diseases of the mouth. Dental plaque is the material that adheres to the teeth and consists of bacterial cells (mainly S. mutans and S. sanguis), salivary polymers and bacterial extracellular products. Plaque is a biofilm on the surfaces of the teeth. This accumulation of microorganisms subject the teeth and gingival tissues to high concentrations of bacterial metabolites which results in dental disease. If not taken care of, via brushing or flossing, the plaque can turn into tartar (its hardened form) and lead to gingivitis or periodontal disease.

In the case of dental cavities, proteins involved in colonization of teeth by Streptococcus mutans can produce antibodies that inhibit the cariogenic process which can be used to create vaccines.

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.

Importance of Dental Hygiene
Maintaining a balanced oral microflora is important for total wellness. The best way to maintain this environment is with proper oral hygiene. Insufficient brushing and flossing can lead to gum and tooth disease, and eventually tooth loss. In addition, poor dental hygiene has been linked to diseases such as osteoporosis, diabetes and cardiovascular diseases. Some diseases and medications are known to limit salivary flow, making it easier for bacteria to overgrow in the mouth without being washed away. To prevent any possible side effects from poor oral hygiene, it is important to brush and floss every day, schedule regular cleanings, eat a healthy diet and use a recently-replaced toothbrush.

Intercellular Communication
Most of the bacterial species found in the mouth belong to microbial communities, called biofilms, a feature of which is inter-bacterial communication. Cell–cell contact is mediated by specific protein adhesins and often, as in the case of inter-species aggregation, by complementary polysaccharide receptors. Another method of communication involves cell–cell signalling molecules, which are of two classes: those used for intra-species and those used for inter-species signalling. An example of intra-species communication is quorum sensing. Oral bacteria have been shown to produce small peptides, such as competence stimulating peptides, which can help promote single-species biofilm formation. A common form of inter-species signalling is mediated by 4, 5-dihydroxy-2, 3-pentanedione (DPD), also known as autoinducer-2(Al-2).