MICROFLORA OF ORAL CAVITY
The oral cavity features more different species of bacteria than any other part of the gastrointestinal system. So-called transit microorganisms get into the oral cavity with air, water, and food. Resident (permanent) bacteria form a stable ecosystem of the oral cavity. There are nearly 30 microbial species. Under normal conditions (no antiseptic paste, antibiotics, etc.) changes of ecosystem depend on the salivary microflora, consistency and nature of the food, as well as oral hygiene regimen, the condition of tissues and organs of the oral cavity and the presence of systemic diseases. Disorders of salivation, chewing and swallowing always lead to an increase in the number of microorganisms in the mouth. Oral microflora is extremely varied and includes bacteria (Spirochetes, Rickettsia, cocci, etc.), fungi (including Actinomycetes), protozoa, viruses. Thus a significant part of oral microorganisms in adults comprise anaerobic species. The concentration of bacteria in the oral fluid ranges from 43 million to 5.5 billion in 1 ml. Microbial concentration in dental plaque and gingival sulcus is 100 times higher - around 200 billion microbial cells per 1 g of the sample (which contains about 80% water). The largest group constantly found in the oral cavity is cocci (85-90% of all species). Streptococci are the main inhabitants of the oral cavity. 1 ml of saliva contains up to 109 Streptococci. Most Streptococci are optional (non-strict) anaerobes, but there are obligate (strict) anaerobes - peptococci. Streptococci fermente carbohydrates, providing a significant amount of lactic acid and other organic acids. In the dental plaque and gingiva of healthy people, there are also Staphylococci - Staph. epidermidis, but in some cases Staph. aureus can be detected, too.