Modern medicine pays attention great importance study of microbial composition and its interaction in the human body, in particular, the influence pathogenic microflora oral cavity on the microbial community and the health of the patient in general.
The internal structure of the mouth is very complex and interconnected with other cavities
It has been established that the cause infectious diseases both the mucous membrane and the teeth and gums are pathogenic microorganisms. Most often they cause various mycoses and stomatitis, which are treated on an outpatient basis using specific antibiotics.
In severe cases, when infection enters the jaw structures or when deep caries When there is a threat of an abscess of the jaw and gums, treatment is recommended in a hospital setting.
The oral cavity is saturated with microorganisms and is a source for them ideal place for growth and reproduction. This is facilitated by:
- optimal temperature;
- humidity;
- constant supply of nutrients;
- features of the anatomical structure that are favorable for the accumulation of microorganisms.
Types of microorganisms living in the mouth
The opportunistic flora is part of the facultative flora and is less numerous in comparison with the obligate flora. Shaping it pathogenic microbes characteristic of specific diseases of the mucous membrane, soft tissues, teeth and jaw structures.
Biotopes
Areas inhabited by obligate and pathogenic flora are called biotopes. The oral cavity is usually divided into 4 biotopes:
- mucous membrane;
- gingival groove and gingival fluid;
- oral fluid;
- dental plaque.
IN normal conditions obligate and facultative groups of microbes together form a balanced microflora in biotopes. When microbial balance is disturbed, active growth of one group of microorganisms occurs to the detriment of another. As a result of the resulting imbalance, opportunistic bacteria become pathogenic and can have a negative effect on the body, although under normal conditions they were harmless.
The most common pathogenic flora of biotopes
Different biotopes are characterized by their own pathogenic microorganisms and the pathologies that are caused by them.
Mucous membrane
This is the mouth's largest biotope by area. Based on its qualitative composition, it can be divided into several parts, each of which is characterized by its own microorganisms:
- the surface of the mucosa is populated by various streptococci;
- Veillonella, peptostreptococci and lactobacilli are located on the mucous membrane of the cheeks, sublingual area, folds and crypts (slit-like folds in the area of the tonsils);
- Streptococci live on the tongue;
- tonsils, soft and hard palates contain a large number of bacteria (corynebacteria, streptococci, neisseria, pseudomonas, etc.) and yeast-like fungi (candida).
The pathogenic effect of pathogenic flora on the mucous membrane is commonly called stomatitis. They are distinguished by the pathogen that caused the lesion.
Stomatitis
The oral mucosa is characterized by viral stomatitis; the cause may be herpes virus, influenza virus, chickenpox or adenovirus. Bacterial stomatitis is most often caused by streptococci, staphylococci and diplococci.
Examples of various stomatitis:
- gangrenous – caused by anaerobic clostridia; accompanied by necrosis of mucosal tissue, the patient’s condition is always serious;
- ulcerative-necrotic – the source is putrefactive flora, primarily fusospirochetal;
- in diphtheria, the lesion is caused by corynebacteria diphtheria, characterized by the formation of white fibrinous films on the pharynx;
- scarlet fever is caused by toxigenic streptococci of the gums, the soft and hard palates are covered with a small rash;
- mycotic stomatitis, caused by a fungus of the genus Candida, manifests itself in the form of a whitish cheesy coating, covers all biotopes of the mouth, and is a symptom of dysbiosis and immunodeficiency.
For many diseases, stomatitis is secondary and takes the form of ulcerations (for tuberculosis, leprosy) or plaques, chancre (for syphilis).
Gingival fluid and gingival groove
The periodontium, which includes the gingival groove and gingival fluid, is characterized by:
- gingivitis (gum inflammation);
- periodontitis, periodontal disease (dystrophic tissue damage);
- periodontomas (tumor-like tissues in the periodontium).
Gingivitis, or inflammation of the gums
A typical cause of periodontal pathologies are obligate bacteria and strict anaerobes - fusobacteria, actinomycetes, leptotrichia, spirilla, spirochetes, bacteroides. Yeast-like fungi, mycoplasmas and protozoa can live in the gingival fluid.
Oral fluid
The most important biotope is a secret salivary glands, saliva containing various microorganisms, scales of exfoliated epithelium, food particles, leukocytes. It is populated in significant numbers by veillonella, facultative anaerobic streptococci, mycoplasma and aerococci, vibrios and pseudomonads, spirochetes and spirilla.
The microflora in the oral fluid can not only survive for a long time, but also fully function and multiply.
Dental plaque
It is a complex and multicomponent biotope, representing a community of microorganisms tightly fixed on one or several teeth. At the same time, soft and sticky dental plaque has a destructive effect on the structure of the tooth to which it is attached. The plaque can also attach to the surface of the filling, and its bacterial composition directly depends on the quality of the filling material. 90% of the plaque is made up of pathogenic flora and its metabolic products.
Dental plaque is a breeding ground for bacteria
The entire pathogenic flora of the oral cavity gradually takes part in the formation of the plaque:
- initially these are anaerobic and facultative anaerobic streptococci, staphylococci, lactobacilli and neisseria;
- they are replaced by fusobacteria and leptotrichia;
- formation is completed by obligate anaerobes (actinomycetes, bacteroides, veillonella, streptococci).
The bacteria that form the plaque are isolated in environment a wide range of toxic enzymes and substances that destroy nearby tissues.
The oral cavity and features of its structure
The oral cavity is a unique formation in the human body - it simultaneously borders both the internal environment through the pharynx and esophagus, and the external environment through the nose and mouth.
A person is born sterile, and with the first cry, it is through the mouth that the colonization of the body with microflora begins, including opportunistic pathogens.
ENT organs are also densely populated with microflora. Certain microorganisms are identified from the ear, throat, nose and pharynx, which under normal conditions are not only not harmful to the human body, but also have a positive effect. These microbes form a polysaccharide framework, a biofilm 0.1-0.5 mm thick, which inhibits the penetration of pathogenic microorganisms into the body, and their secretions help suppress pathogenic flora.
Division of microflora into types
All oral microflora can be divided into several types:
- Saprophytes adapted to the conditions of the mouth are present in physiological balance and are not pathogenic.
- Transit flora passes through the mouth or enters accidentally. Often this type of microbe is pathogenic and can have a negative effect on the body - the oral route of infection.
- Opportunistic pathogens that are constantly present in the mouth live and reproduce. In a healthy body under normal conditions they do not manifest themselves at all. But when the protective properties are weakened, this group of microorganisms acquires pathogenic properties and is the cause of a number of negative processes in the oral cavity.
- A group of unpretentious bacteria that, by processing sugar, have adapted to exist in the mouth almost independently of the human body. Colonies look like soft plaque, which can only be removed mechanically. Due to the autonomy of the supra- and subgingival plaque on the teeth, both saprophytic and pathogenic flora can exist for a long time.
Methods for identifying pathogens
Pathogenic microorganisms cause various disorders, to eliminate which it is necessary to know which bacteria affect the body. Symptoms of the disease help identify the pathogen; in addition, various methods analyses. For example, a micro-examination of a smear from the throat and nose can identify the cause of frequent sore throats (beta-hemolytic streptococcus) or the causative agent of furunculosis (Staphylococcus aureus).
If there are symptoms of an inflammatory disease, material for analysis is taken taking into account the anatomical unity of the oral cavity and ENT organs: for example, it should be taken into account that the causative agents of the disease can be located not only on the palatine tonsils, but also in carious dental cavities.
Microbiological imbalance
The result of exposure to pathogenic microflora will always be a violation of the microbiological balance - dysbacteriosis. In practice, this looks like oppression and displacement of one group of obligate microorganisms by growing facultative microflora.
Consequently, the treatment of dysbacteriosis itself is a meaningless action, since it is not a cause, but a consequence. Simply suppressing the growth of a certain group of pathogenic microorganisms is not always possible and ineffective.
Most typical reasons occurrence of dysbacteriosis:
- chronic and acute diseases of the ENT organs and oral cavity;
- adverse external influences (overheating, hypothermia, etc.);
- treatment with antibiotics or hormonal drugs;
- high physical, mental and emotional stress;
- starvation, hypovitaminosis;
- bad habits (smoking, alcoholism).
Basics of microflora normalization
In the mouth there are ideal conditions for the life of microorganisms, one of the factors of which is the presence of food. But pathogenic microflora actively multiply on leftover food, causing caries and periodontal disease.
Rules for using dental floss
Nature has provided a natural mechanism for freeing the mouth from food debris - self-cleaning. The swallowing mechanism, circulation of oral fluid, movements of the cheeks, tongue, jaws and lips are involved in its process. Self-purification is a powerful tool that suppresses the development of pathogenic microflora.
U modern man self-cleaning of the mouth from food debris has partially lost its effectiveness. This is due to a change in the nature of nutrition - people began to eat a minimum amount of rough food, most of the diet consists of soft foods that easily accumulate in small cavities mouth (interdental spaces, cervical area of the tooth, etc.). As a result, sticky food particles are deposited in the mouth on hard and soft surfaces, on which pathogenic microflora grow.
In this situation, the natural antibacterial factors of the oral cavity, the sources of which are gingival fluid and saliva containing bacteriological and bacteriostatic products, are no longer enough.
Mechanical cleaning of the oral cavity
The process of self-cleaning in modern humans is hampered by the weakening of the dentofacial apparatus, which leads to a decrease in saliva secretion, the presence of caries, various pathologies and deformations. Taking into account the difficulties that have arisen, it is advisable to carry out mechanical cleansing of the oral cavity.
In addition to brushing your teeth, dentists recommend using dental floss after every meal. The effectiveness of its use has been proven - the thread allows you to remove plaque in hard-to-reach places without injury to the periodontium.
Doctors attach great importance to cleaning the tongue in the fight against pathogenic microorganisms - the first mention of a tongue scraper dates back to the 11th century. Today, to clean the surface of the tongue, there are special mechanical and electric brushes that allow you to efficiently remove plaque in which anaerobic bacteria multiply.
A variety of devices are used to clean the tongue: from brushes to scrapers.
For high-quality cleansing of the oral cavity from food debris, dentists recommend the following scheme:
- brushing teeth after every meal;
- regular flossing;
- rinsing your mouth with water after brushing your teeth;
- brushing your tongue every evening.
Mechanical cleaning methods will help self-clean the oral cavity from food debris and plaque. This will reduce the number of pathogens and help normalize the microflora of the oral cavity.
There are about 160 types of microorganisms in the oral cavity - this is one of the most contaminated parts of the human body.
Microorganisms enter the oral cavity with food, water, and from the air. There are favorable conditions for their development: always uniform humidity, fairly constant temperature (about 37 ° C), sufficient oxygen content, slightly alkaline pH, and an abundance of nutrients. The development of microorganisms is also facilitated by the anatomical features of the oral cavity: the presence of folds of the mucous membrane, interdental spaces, gingival pockets in which food debris and deflated epithelium are retained. All this explains the fact that the microbial flora of the oral cavity is not only abundant, but also diverse.
Microorganisms in the oral cavity are distributed unevenly. They are found in large quantities on the back of the tongue and the surface of the teeth. 1 g of dental plaque contains about 300 billion microbes, saliva contains less of them - about 900 million in 1 ml.
The number of microorganisms in the oral cavity is subject to significant fluctuations, but the species composition of the microflora (autoflora) in healthy people is characterized by a certain constancy.
P.V. Tsiklinskaya (1859-1923) proposed to distinguish between permanent (resident) and non-permanent microflora of the oral cavity.
1.1. Constant microflora of the oral cavity
Resident microflora of the oral cavity includes representatives of all classes of microorganisms: bacteria, actinomycetes, spirochetes, fungi, protozoa, and viruses. Bacteria predominate, with about 90% of microbial species being anaerobes.
The most extensive group of bacteria inhabiting the oral cavity are coccoid forms.
Streptococci. They are one of the main inhabitants of the oral cavity. They are found in 100% of people in saliva (up to 10 8 - 10 9 streptococci in 1 ml) and in gingival pockets.
Streptococci are spherical or oval in shape, gram-positive, nonmotile, and do not form spores. In smears from cultures on solid media they are located in pairs or short chains, in preparations from broth cultures - in long chains and clusters.
According to the type of respiration, they are classified as facultative anaerobes; obligate anaerobes (Peptostreptococci) are also found. Temperature limits for growth vary depending on the species, the optimal temperature is about 37 "C.
They do not grow on simple media or produce very poor growth. To cultivate streptococci, blood, serum, ascitic fluid, and glucose are added to the media. Streptococci form small (about 1 mm in diameter), translucent, grayish or colorless colonies. The broth is characterized by bottom-wall growth. On media with blood they can cause hemolysis of red blood cells. According to the nature of hemolysis, they are divided into three groups: 1) p-hemolytic - colonies are surrounded by a zone of complete hemolysis; 2) a-hemolytic (greening) - cause partial hemolysis around the colonies and give a greenish color due to the conversion of hemoglobin into methemoglobin; 3) y-streptococci - do not have hemolytic activity.
Carbohydrates are fermented with the formation of almost exclusively lactic acid, causing lactic acid fermentation.
Thanks to this, they are strong antagonists against many putrefactive bacteria found in the oral cavity.
Streptococci produce a number of exotoxins and aggressive enzymes (hemolysin, leukocidin, erythrogenic toxin, hyaluronidase, streptokinase, O- and S-streptolysins, etc.).
They have a complex antigenic structure. There are 17 known serological groups of streptococci, designated by capital letters from A to S. The cell wall contains a group-specific polysaccharide C-antigen (hapten), which is approximately 10 % dry cell mass.
There are streptococci that do not contain group C-antigen and therefore do not belong to any of the 17 serological groups. Streptococci that do not have a group-specific C-antigen are constantly found in the oral cavity. All of them are green or non-hemolytic, devoid of such signs of pathogenicity as the ability to produce streptolysins and streptokinase. However, it is these streptococci that most often cause inflammatory processes in the oral cavity.
Typical representatives of streptococci that do not have a group C antigen are S. salivarius and S. mitis, which are found in the oral cavity in 100% of cases. A characteristic feature of S. salivarius is the formation of a capsule as a result of the synthesis of viscous polysaccharides from sucrose. In places where caries is most frequently localized (in the fissure area, on the proximal surfaces of teeth), S. mutans is found, which is difficult to differentiate from S. salivarius. It is believed that S. mutans plays a leading role in the occurrence of dental caries.
In addition to streptococci lacking a group antigen, representatives of almost all 17 groups are found in the oral cavity, but they occur less consistently and in much smaller quantities.
Peptostreptococci - obligate anaerobes - are permanent inhabitants of the oral cavity. There are 13 types of peptostreptococci. They play an important role in mixed infections, as they enhance the pathogenic effect of other microorganisms.
Staphylococcus. Found in saliva in 80% of cases, often in periodontal pockets.
The cells are spherical in shape, arranged in clusters resembling bunches of grapes (Staphylon - bunch). Gram-positive, non-motile, do not form spores. -
They grow at temperatures from 7 to 46 ° C, the temperature optimum is 35 - 40 "C. Facultative anaerobes. Unpretentious, grow well on simple nutrient media, forming medium-sized colonies, round, smooth, convex, various shades of yellow or white (depending on from the pigment produced) On liquid media they give uniform turbidity.
They have pronounced enzymatic activity. Many carbohydrates ferment to form acid. They break down proteins to release hydrogen sulfide. Indole is not formed.
According to modern classification, the genus Staphylococcus is divided into three species:
2) S. epidermidis;
3) S. saprophyticus.
Staphylococcus aureus (S. aureus) has a number of pathogenicity characteristics. Unlike other species of staphylococcus, they coagulate citrated plasma and ferment mannitol under anaerobic conditions.
In the oral cavity of healthy people (on the gums, in dental plaque), predominantly S. epidermidis is found. In some people, Staphylococcus aureus may also be present in the oral cavity. However, much more often S. aureus is localized on the mucous membrane of the anterior sections of the nasal cavity and pharyngeal mucosa, causing bacteria carriage. Under appropriate conditions, they can cause purulent-inflammatory processes in the oral cavity. Due to their pronounced enzymatic activity, staphylococci take part in the breakdown of food debris in the oral cavity.
Veillonella. Bacteria of the genus Veillonella are small gram-negative cocci. The cells are spherical in shape and in smears are arranged in pairs, in the form of clusters or short chains. Motile, do not form spores.
Obligate anaerobes. They grow well at 30-37 °C. On solid nutrient media, they form colonies 1-3 mm in greatest dimension. The colonies are smooth, oily, grayish-white in color, lenticular, diamond-shaped or heart-shaped in shape. They are classified as chemoorganotrophs with complex nutritional needs.
Carbohydrates and polyhydric alcohols do not ferment. They do not liquefy gelatin, do not form indole, and do not have hemolytic activity. Produce hydrogen sulfide. The crops emit a characteristic foul odor.
Veillonella contain lipopolysaccharide endotoxins. Two types of these cocci were found in the oral cavity: Veillonella parvula and Veillonella alcalescens, which are constantly present in large quantities (up to 10 7 - 10 8 in 1 ml of saliva). Their number increases during purulent-inflammatory processes in the oral cavity, especially with alveolar pyorrhea and odontogenic abscesses.
Neisseria. Gram-negative, bean-shaped diplococci. The genus Neisseria includes saprophytic and pathogenic microorganisms (pathogenic ones include meningococci and gonococci).
Saprophytic Neisseria are always found in large numbers in the oral cavity of healthy people
(1-3 million in 1 ml of saliva). All of them are aerobic (with the exception of N. dis-coides). Unlike pathogenic ones, saprophytic neisseria grow well on simple nutrient media even at room temperature. Optimal growth temperature 32...37 °C. There are pigment-forming species: N. flavescens. N. pha-ryngis - pigment of various shades of yellow and non-pigment forming (N. sicca). Biochemically, Neisseria are inactive - only a few carbohydrates are fermented.
Branhamellas. They are cocci, usually arranged in pairs. Gram-negative, immobile, do not form spores.
By type of respiration they are classified as aerobes. Temperature optimum is about 37 °C. Grows on normal media. Carbohydrates are not fermented.
Branhamella catarrhalis is found in the oral cavity. In mucosal smears, they are often located within leukocytes. Some strains are pathogenic for guinea pigs and mice.
N. sicca and B. catarrhalis are most often found in the pulp and periodontium during acute serous inflammation. They multiply intensively during catarrhal inflammation of the mucous membrane of the oral cavity and upper respiratory tract.
In addition to the coccal microflora, the inhabitants of the oral cavity are a variety of rod-shaped bacteria.
Lactic acid bacteria (lactobacillus). In 90% of healthy people, lactic acid bacteria live in the oral cavity (1 ml of saliva contains 10 3 -10 4 cells).
Bacteria of the genus Lactobacillus are rods from long and thin to short type of coccobacilli. They often form chains. Motile, do not form spores or capsules. Gram-positive, with aging of the culture and with increasing acidity they become gram-negative.
They can grow at temperatures from 5 to 53 °C, the optimal temperature is +30...40 °C. Acid-loving, optimum pH 5.5-5.8. Microaerophiles grow much better under anaerobic conditions than under aerobic conditions.
Demanding on nutrient media. For their growth, certain amino acids, vitamins, salts, fatty acids, etc. are necessary. On elective nutrient media, colonies are small, colorless, and flattened.
They differ from each other in their saccharolytic properties; on this basis, homofermentative and heterofermentative species are distinguished.
Homofermentative species (Lactobacillus casei, L. Lactis) produce only lactic acid when fermenting carbohydrates.
Heterofermentative species (L fermentum, L. brevis) produce about 50% lactic acid, 25% CO2 and 25% acetic acid and ethyl alcohol.
Due to the formation of large amounts of lactic acid, lactobacilli are antagonists of other microbes: staphylococci, E. coli and other enterobacteria. The antagonistic properties of lactic acid bacteria were already noticed by I.I. Mechnikov, who proposed using curdled milk from milk fermented with L. bulgaricus to suppress putrefactive bacteria in the intestines.
Up to 90% of lactobacilli living in the oral cavity belong to L. casei and L. fermentum. Lactic acid bacilli do not have pathogenic properties, but their number increases sharply with dental caries. To assess the activity of the carious process, a “lactobacillentest” has even been proposed - determining the number of lactobacilli.
Bacteroides. Bacteroides are always present in the oral cavity of healthy people - anaerobic gram-negative non-spore-forming rods belonging to the Bacteroidaceae family. They are distinguished by great polymorphism - they can have a rod-shaped, thread-like or coccoid shape. Does not form capsules. Most species are motionless. They grow on media supplemented with protein (blood, serum, ascitic fluid). Carbohydrates are fermented to form succinic, lactic, butyric, propionic and other acids.
The family Bacteroidaceae includes several genera. The inhabitants of the oral cavity are representatives of the genera Basteroides, Fusobacterium, and Leptotrichia.
Actually, Bacteroides are regularly found in the oral cavity (thousands of microbial cells in 1 ml of saliva). The most common species are B. melaninogenicus, B. oralis, B. fragilis, etc.
The number of bacteroids increases with various purulent-inflammatory processes in the oral cavity (in suppurating dental granulomas, with osteomyelitis of the jaws, actinomycosis, as well as with purulent-inflammatory processes in other organs - lungs, kidneys, etc.). Bacteroides are often found in combination with other microorganisms, mainly anaerobic. The fundiliformis produces an exotoxin. When administered intradermally to guinea pigs or
in rabbits it causes skin necrosis; when administered intravenously, it causes septicopyemia with purulent foci in various organs and tissues. In humans, with a decrease in reactivity, it can cause severe “fundiliformis - sepsis” with the formation of abscesses in the joints, liver, lungs, and brain. The entrance gates in this case may be the tonsils and wound surfaces, for example, after tooth extraction, in case of traumatic injuries to the facial bones.
Bacteria of the genus Fusobacterium are spindle-shaped rods with pointed ends. The cytoplasm contains granules that stain gram-positive, while the cytoplasm itself stains gram-negative. Motile, do not form spores or capsules. Fusobacteria differ in their saccharolytic and proteolytic activity.
The saccharolytic group includes F. plauti and some others. They ferment carbohydrates to produce large amounts of acid. Non-pathogenic for animals.
Proteolytic species (F. nucleatum, F. biacutum) break down proteins with the formation of hydrogen sulfide; the crops emit a putrid odor. Sometimes they are pathogenic for animals (cause peritonitis, abscesses).
Fusobacteria are constantly present in the oral cavity (1 ml of saliva contains several tens of thousands of microbes). Their number increases sharply in various pathological processes (with Vincent's angina, gingivitis, stomatitis - 1000-10000 times). Fusobacteria are found in carious dentin, in gum pockets during periodontitis.
Bacteria of the genus Leptotrichia are large, straight or slightly curved rods with rounded or more often pointed ends. They form threads that can intertwine with each other. They are immobile, do not form spores or capsules, and are gram-negative. Obligate anaerobes. They grow on media supplemented with serum or ascitic fluid. Carbohydrates are fermented to form lactic acid. There are a large number of species of Leptotrichia known, all of them contain a common antigen, which is detected using the complement fixation reaction (CFR). They are constantly present in the oral cavity and in large quantities (10 3 -10 4 cells in 1 ml of saliva). Most often localized at the neck of the tooth. The matrix (organic basis) of dental calculus consists mainly of leptotrichia. A representative of leptotrichia - inhabitants of the oral cavity - is L. buccalis.
Actinomycetes. Found in saliva in almost 100% of people, they are very often found in gum pockets. Actinomycetes are a group of filamentous bacteria. According to the International Classification, they are separated into an independent group, the order Actinomycetales, family Actinomycetaceae. The same group includes related microorganisms - Corine and mycobacteria.
Actinomycetes are gram-positive and tend to form branched filaments in tissues or on nutrient media. The threads are thin (diameter 0.3-1 microns), do not have partitions, and are easily fragmented, which leads to the formation of rod-shaped or coccoid forms. They are immobile and do not form spores, unlike bacteria of the family. Streptomycetaceae.
According to the type of respiration, they are facultative anaerobes; most prefer anaerobic conditions. They grow at temperatures from 3 to 40 °C, the optimal temperature is 35-37 °C.
Actinomycetes are cultivated on media containing serum, blood, ascitic fluid, and organ extracts (heart, brain). Growth is slow, mature colonies are formed on the 7-15th day. Colonies are small (0.3-0.5 mm), less often large, and may have a smooth or folded, bumpy surface. The consistency of the colonies is leathery or crumbly; some colonies are difficult to separate from the nutrient medium. They form a pigment, thanks to which colonies can be colored blackish-violet, orange, greenish, white, brown. In liquid media they grow as a film on the surface or as a sediment.
Carbohydrates are fermented to form acid. They usually do not have proteolytic activity.
The antigenic structure has not been sufficiently studied. Type- and species-specific antigens were discovered. The issue of toxin formation is also insufficiently studied. It is assumed that pathogenic actinomycetes contain endotoxin.
Actinomycetes are inhabitants of the skin and mucous membranes; they are present in dental plaque, on the surface of the gums, in periodontal pockets, in carious dentin, in the crypts of the tonsils. A. Israeli!, A. viscosus are usually found in the oral cavity. The number of actinomycetes increases sharply in various dental diseases, accompanied by an increase in the number of anaerobic microorganisms. They can cause damage to various tissues and organs, called actinomycosis.
In healthy people, a number of other rod-shaped and convoluted forms are found in the oral cavity: corynebacteria (diphtheroids), hemophilus bacteria (Haemophilus influenzae - Afanasyev-Pfeiffer bacillus), anaerobic vibrios (Vibrio sputorum), spirillum (Spirillum sputigenum), etc.
Spirochetes of the oral cavity. Any healthy person has a large number of saprophytic spirochetes in the oral cavity. They are found mainly in gum pockets.
The spirochete cell consists of axial fibrils, forming an axial filament, and a protoplasmic cylinder, spirally curled around the filament. The protoplasmic cylinder and axial fibrils are enclosed in an outer shell. Axial fibrils are attached to the ends of the protoplasmic cylinder; from the point of attachment they stretch to the opposite pole of the cell; they can extend beyond the ends of the protoplasmic cylinder, creating the impression of flagella, but unlike true flagella, they are enclosed in an outer shell.
Spirochetes are motile. They perform three types of movements: rotational, flexion, and wave-like.
Saprophytic spirochetes belonging to three genera of the Spirochaetaceae family are constantly present in the oral cavity:
Borrelia are spiral cells with 3-10 large, uneven turns. Gram negative. According to Romanovsky-Giemsa, they are colored blue-violet. Obligate anaerobes. The inhabitant of the oral cavity is Borrelia buccalis.
Treponemas look like tightly twisted spirals. The curls are uniform and small. Gram negative. Strict anaerobes. In the oral cavity there are: Treponema macrodentium, T. microdentium (in morphology it is very similar to the causative agent of syphilis T. pallidum), T. vincentii.
Leptospira is present in the oral cavity Leptospira dentium. By morphological characteristics L dentium is no different from other members of the genus. The cells are shaped like spirals with small turns. One or both ends can be bent into a hook. Obligate aerobes.
In pure culture, spirochetes found in the oral cavity are not pathogenic for humans and animals. They cause pathological processes in combination with other microorganisms, cocci, fusobacteria, and vibrio. A large number of spirochetes are found in ulcerative stomatitis, Vincent's sore throat, in periodontal pockets in severe forms of periodontitis, in carious lesions and necrotic pulp.
Yeast-like fungi of the genusCandida. Distributed everywhere. They are constantly found in microbial associations on the skin, mucous membranes of open human cavities, and in the intestines.
The genus Candida includes about 100 species, most of which are not pathogenic to humans. There are also opportunistic species that can cause diseases when the body's defenses are reduced. These include C. albicans, C. krusei, C. tropicalis, C. pseudotropicalis, etc.
Cells of fungi of the genus Candida can be round, ovoid, cylindrical, sometimes irregular in shape, their diameter ranges from 5 to 8 microns. They reproduce by multipolar budding. They do not have true mycelium; they form pseudomycelium, consisting of chains of elongated cells.
Gram-positive, can be stained unevenly: the peripheral layer of the cell is purple, the central part is pinkish; Entirely gram-negative cells are found. According to Ziehl-Neelsen, fungal cells are stained blue with red inclusions of lipoids.
By type of respiration they are classified as aerobes. The optimal growth temperature is 30...- 37 °C, they grow somewhat slower at room temperature.
They can be cultivated on simple nutrient media; they grow better on media containing carbohydrates, serum, blood, and ascitic fluid. The most common election medium is Sabouraud's medium (which contains glucose or maltose and yeast extract).
On dense media they form large, creamy, yellowish-white colonies with a smooth or rough surface. Ingrowth of fungi into the nutrient medium is typical. Colonies mature by the 30th day. In liquid media they grow in the form of a film and small grains on the bottom and walls of the test tube.
They ferment many carbohydrates to acid and gas, liquefy gelatin, but very slowly.
The antigenic structure is quite complex. Fungal cells are full-fledged antigens; in response to them, the body develops specific sensitization and produces corresponding antibodies.
Yeast-like fungi are found in the oral cavity of healthy people (10 2 -10 3 cells in 1 ml of saliva), and there is a tendency towards their wider distribution. Thus, in 1933, C. albicans were isolated from the oral cavity in 6% of healthy people, in 1939 - in 24%, in 1954 - in 39%.
Currently, these fungi are found in 40-50% of cases in the oral cavity of healthy people.
When the body's reactivity decreases, fungi of the genus Candida can cause diseases called candidiasis or candidiasis.
The simplest oral cavity. In 45-50% of healthy people, the inhabitant of the oral cavity is Entamoeba gingivalis. These microorganisms are found mainly in gum pockets, tonsil crypts, and dental plaque.
E. gingivalis has a diameter of 20-30 microns, is very mobile, "better visible in the native unstained preparation (crushed drop). Aerobic. Cultivated on blood or serum agar, coated with a layer of Ringer's solution with the addition of tryptophan (1:10,000).
In 10-20% of people, Trichomonas elongata (Trichomonas tenax) lives in the oral cavity; it is pear-shaped, 7-20 microns long. At the anterior end there are four flagella extending from the basal granules. One of the flagella borders the undulating membrane. At the base of the flagella there is a slit-like depression. It is believed that it serves to capture food (bacteria). Trichomonas are mobile and clearly visible in the living state in unstained preparations. They are cultivated in the same way as amoebas.
Amoebas and Trichomonas multiply intensively due to unhygienic maintenance of the oral cavity, as well as with gingivitis and periodontitis.
Microflora of the oral cavity: norm and pathology
Tutorial
2004
Preface
In recent years, there has been an increase in the interest of dentists in fundamental disciplines, including medical microbiology and immunology. Of all the branches of microbiology for the special training of a dentist, the section that studies the normal, or resident, human flora, in particular the indigenous microflora of the oral cavity, is of paramount importance. Caries and periodontal diseases, which occupy one of the leading places in human pathology, are associated with the constant microflora of the oral cavity. There is ample evidence that the incidence of them in the population in many countries reaches 95-98%.
For this reason, knowledge of the ecology of the oral cavity, the mechanisms of formation of normal microbial flora, and factors regulating the homeostasis of the oral ecosystem is absolutely necessary for dental students. The textbook “Oral Microflora: Norm and Pathology” presents in an accessible form modern data on the importance of normal flora and mechanisms of local immunity of the oral cavity in the occurrence of oral pathology.
This manual has been prepared in accordance with curriculum on the topic “Microbiology of the Oral Cavity” and complements the section “Microbiology and Immunology of Dental Diseases” of the textbook by L.B. Borisova “Medical microbiology, virology, immunology”, M., Medicine, 2002.
Head department therapeutic dentistry NSMA Doctor of Medical Sciences, Professor
L.M. Lukins
Lecture 1
Microbial flora of the oral cavity is normal
| Microorganisms | In saliva | Frequency of detection in periodontal pockets, % | |
| Detection rate, % | Quantity in 1 ml | ||
| Resident flora 1. Aerobes and facultative anaerobes: | |||
| 1. S. mutans | 1.5´10 5 | ||
| 2. S. salivarius | 10 7 | ||
| 3. S. mitis | 10 6 – 10 8 | ||
| 4. Saprophytic Neisseria | 10 5 – 10 7 | + + | |
| 5. Lactobacilli | 10 3 – 10 4 | + | |
| 6. Staphylococcus | 10* 3 – 10* 4 | + + | |
| 7. Diphtheroids | Undefined | = | |
| 8. Hemophiliacs | Undefined | ||
| 9. Pneumococci | Undefined | Undefined | |
| 1. Other cocci | 10* 2 – 10* 4 | + + | |
| 1. Saprophytic mycobacteria | + + | Undefined | + + |
| 2. Tetracocci | + + | Undefined | + + |
| 3. Yeast-like fungi | 10* 2 – 10* 3 | + | |
| 4. Mycoplasmas | 10* 2 – 10* 3 | Undefined | |
| 2. Obligate anaerobes | |||
| 1. Veillonella | 10* 6 – 10* 8 | ||
| 2. Anaerobic streptococci (peptostreptococci) | Undefined | ||
| 3. Bacteroides | Undefined | ||
| 4. Fusobacteria | 10* 3 – 10* 3 | ||
| 5. Filamentous bacteria | 10* 2 – 10* 4 | ||
| 6. Actinomycetes and anaerobic diphtheroids | Undefined | + + | |
| 7. Spirilla and vibrios | + + | Undefined | + + |
| 8. Spirochetes (saprophytic Borrelia, Treponema and Leptospira) | ± | Undefined | |
| 3. Protozoa: | |||
| 1. Entamoeba gingivalis | |||
| 2. Trichomonas clongata | |||
| Fickle flora 1. Aerobes and facultative anaerobes Gram-negative rods: | |||
| 1. Klebsiella | 10 – 10* 2 | ||
| 2. Escherichia | 10 – 10* 2 | ± | |
| 3. Aerobacter | 10 – 10* 2 | ||
| 4. Pseudomonas | ± | Undefined | |
| 5. Proteus | ± | Undefined | |
| 6.Alkaligenes | ± | Undefined | |
| 7. Bacillus | ± | Undefined | |
| 2. 2. Obligate anaerobes: Clostridia: | |||
| 1. Clostridium putridium | ± | Undefined | |
| 2. Clostridium perfingens | ± | Undefined | |
Lecture 2
Lecture 3
Lecture 4
Microflora of dental plaque
1. Brief information about the structure of hard dental tissues. 2. Organic membranes covering the tooth enamel. 3. Composition of dental plaque. 4. Dynamics of plaque formation. 5. Factors influencing the formation of dental plaque. 6. Mechanisms of plaque formation. 7. Physical properties of dental plaque. 8. Microorganisms of dental plaque. 9. Cariogenicity of dental plaque.
1. Brief information about the structure of hard dental tissues. The hard part of the tooth consists of enamel, dentin and cement (Fig. 1).
Dentin makes up the main part of the tooth. The crowns of the teeth are covered with enamel - the hardest and most durable tissue human body. The root of the tooth is covered with a thin layer of bone-like tissue called cementum and surrounded by periosteum, through which the tooth is nourished. Fibers run from the cement to the periosteum, forming the so-called dental ligament (periodontal ligament), which firmly strengthens the tooth in the jaw. Inside the crown of the tooth there is a cavity filled with loose connective tissue called pulp. This cavity continues in the form of canals into the root of the tooth.
2. Organic membranes covering the tooth enamel. The surface of the enamel is covered with organic shells, as a result of which, when examined under an electron microscope, it has a smoothed relief; nevertheless, there are convex and concave areas that correspond to the ends of the prisms (the smallest structural units enamel are crystals of an apatite-like substance that form enamel prisms). It is in these areas that microorganisms first begin to accumulate or food debris may become trapped. Even mechanical cleaning of enamel with a toothbrush is not able to completely remove microorganisms from its surface.
Rice. 1. Tooth structure: 1 - crown; 2 - root; 3 - neck; 4 - enamel; 5 - dentin; 6 - pulp; 7 - mucous membrane of the gums; 8 - periodontium; 9 - bone tissue; 10 - root apex hole
On the surface of teeth one can often observe dental plaque (P), which is a white soft substance localized in the neck of the tooth and on its entire surface. The pellicle, which lies under the layer of dental plaque and is a thin organic film, is a structural element of the surface layer of enamel. A pellicle forms on the surface of a tooth after it has erupted. It is believed that it is a derivative of protein-carbohydrate complexes of saliva. Electron microscopy of the pellicle revealed three layers and a characteristic feature - a jagged edge and niches, which are receptacles for bacterial cells. The thickness of the daily pellicle is 2-4 microns. Its amino acid composition is somewhere between the composition of dental plaque and salivary mucin precipitate. It is high in glutamic acid, alanine and low in sulfur-containing amino acids. The pellicle contains a large number of amino sugars, which are derivatives of the bacterial cell wall. No bacteria are observed in the pellicle itself, but it contains components of lysed bacteria. Perhaps the formation of a pellicle is the initial stage of dental plaque. Another organic shell of the tooth is the cuticle (reduced enamel epithelium), which is lost after tooth eruption and subsequently does not play a significant role in the physiology of the tooth. In addition, the mucous membrane of the oral cavity and teeth are covered with a thin film of mucin secreted from saliva.
Thus, the following formations are noted on the surface of the tooth enamel:
· cuticle (reduced enamel epithelium);
· pellicle;
· plaque;
· food leftovers;
· mucin film.
The following scheme for the formation of acquired surface tooth structures has been proposed: after teething, the enamel surface is exposed to saliva and microorganisms. As a result of erosive demineralization, ultramicroscopic tubules are formed on the surface of the enamel, which penetrate into the enamel to a depth of 1-3 microns. Subsequently, the tubules are filled with an insoluble protein substance. Due to the precipitation of salivary mucoproteins, as well as adhesion and growth, and then destruction of microorganisms, a thicker organic layer is formed on the surface cuticle, in varying degrees mineralized pellicle layer.
Thanks to local conditions, microbes invade these structures and multiply, leading to the formation of soft MN. Mineral salts are deposited on the colloidal basis of the ON, greatly changing the ratio between mucopolysaccharides, microorganisms, salivary bodies, desquamated epithelium and food debris, which ultimately leads to partial or complete mineralization of the ON. When its intensive mineralization begins, tartar can form, which occurs by impregnation of the neutron with calcium phosphate crystals. The time required for hardening of the soft matrix is about 12 days. The fact that mineralization has begun becomes obvious within 1-3 days after plaque formation.
3. Composition of dental plaque. With the help of biochemical and physiological studies, it has been established that MN is an accumulation of colonies of microorganisms incorporated into the matrix that live in the oral cavity and on the surface of the teeth.
In studies using scanning electron microscope it was shown that the MN consists exclusively of microorganisms with an insignificant inclusion of structureless substance of organic nature. Protein, carbohydrates, and enzymes were identified among the organic components in GL. Its amino acid composition differs from that of mucin and pellicle, as well as saliva. The carbohydrate components of MN (glycogen, acid mucopolysaccharides, glycoproteins) have been most fully studied.
There is a hypothesis that MN enzymes play important role in the carious process. Chemical composition MN varies greatly in different parts of the oral cavity and in different people depending on age, sugar intake, etc. Calcium, phosphorus, potassium, and sodium were found in dental plaque. About 40% of the dry mass of inorganic substances is in the form of oxyapatite. The content of microelements in MN is extremely variable and has not been studied enough (iron, zinc, fluorine, molybdenum, selenium, etc.). Assumptions about the mechanisms of the caries-inhibiting effect of microelements are based on their effect on the activity of bacterial enzymes, as well as on the ratio of different groups of microorganisms. Certain microelements (fluorine, molybdenum, strontium) cause less susceptibility of teeth to caries, affecting the ecology, composition and exchange of dental tissue; Selenium, on the contrary, increases the likelihood of caries. One of the most important components influencing the biochemistry of neutrons is fluorine. There are three ways to incorporate fluorine into GL: the first - through the formation of inorganic crystals (fluorapatite), the second - through the formation of a complex with organic substances (with plaque matrix protein); the third is the penetration of bacteria inside. Interest in the metabolism of fluoride in MN is associated with the anti-caries effect of this microelement. Fluorine, firstly, affects the composition of dental plaque, secondly, it affects the solubility of enamel, and thirdly, it suppresses the work of bacterial enzymes that are part of dental plaque.
Inorganic substances of MN are directly related to the mineralization and formation of tartar.
4. Dynamics of plaque formation. ZN begins to accumulate within 2 hours after brushing your teeth. Within 1 day, coccal flora predominates on the tooth surface, after 24 hours, rod-shaped bacteria predominate. After 2 days, numerous rods and filamentous bacteria are found on the surface of the MN (Fig. 2).
As MN develops, its microflora changes according to the type of respiration. The initially formed plaque contains aerobic microorganisms, while the more mature plaque contains aerobic and anaerobic bacteria.
A certain role in the formation of tumors is played by desquamated epithelial cells, which attach to the tooth surface within an hour after it is cleansed. The number of cells increases significantly by the end of the day. Next, the epithelial cells adsorb microorganisms on their surface. It has also been established that carbohydrates contribute significantly to the formation of tumors and their adhesion to enamel.
The most important role in the formation of stains is played by S. mutans, which actively forms it on any surface. But there is a certain sequence in this process. Under experimental conditions, it was shown that S. salivarius first adheres to a clean tooth surface, and then S. mutans adheres and begins to multiply. In this case, S. salivarius very quickly disappears from dental plaque. Enzymes influence the formation of the MN matrix bacterial origin, for example, neuraminidase, which is involved in the breakdown of glycoproteins to carbohydrates, as well as in the polymerization of sucrose to dextran-levan.
IgA, IgM, IgG, amylase, lysozyme, albumin and other protein substrates that may be involved in the formation of tumors are found in saliva. The pellicle, as a rule, contains all classes of immunoglobulins (A, M, G), while IgA and IgG are most often detected in the ON (however, the share of IgA in the formation of ON is very small: only about 1% of IgA is involved in this process , even less participation of IgG). It has been established that immunoglobulins coat the tooth and bacteria that can adhere to the tooth pellicle. GN bacteria can become coated with antibodies coming from saliva or gingival philtrum fluid.
Rice. 2. Microorganisms on the surface of dental plaque (electronogram)
The role of sIgA in the formation of dental plaque is being actively studied. It is found in the pellicle in a biologically active state in large quantities. Apparently, sIgA can play a dual role in the formation of dental plaque. Firstly, salivary sIgA can reduce the adhesion of bacteria to enamel and thus inhibit the formation of tumors and then dental plaques. Secondly, sIgA, under certain conditions, promotes the adhesion of indigenous flora to enamel hydroxyapatite (especially during the synthesis of S.mutans glucan). In addition, it has been shown that S. mutans coated with sIgA and IgG can release bound antibodies in the form of antigen-antibody immune complexes (AG+AT) and thus reduce the inhibitory effect of antibodies on bacterial adhesion to hydroxyapatite.
When studying the dynamics of growth of nuclei under experimental conditions, it was found that during the first 24 hours a film of a homogeneous substance, free of bacteria, 10 μm thick, is formed. In the following days, bacteria are adsorbed and grow. After 5 days, plaque covers more than half of the tooth crown and the quantity significantly exceeds the initial daily plaque. It accumulates most quickly on the buccal surfaces of the upper chewing teeth. The spread of tumors over the tooth surface occurs from the interdental spaces and gingival grooves; the growth of colonies is similar to the development of the latter on a nutrient medium.
The proximal surfaces of the teeth are the least cleaned.
5. Factors influencing the formation of plaque:
1) microorganisms, without which ZN is not formed;
2) carbohydrates (relatively large amounts of plaque are found in people who consume a lot of sucrose);
3) saliva viscosity, oral microflora, bacterial coaggregation processes, desquamation of the epithelium of the oral mucosa, the presence of local inflammatory diseases, self-cleaning processes.
6. Mechanisms of plaque formation. There are three theories of the occurrence of MN:
1) gluing of epithelial cells invaded by bacteria to the surface of the tooth with the subsequent growth of bacterial colonies; coaggregation of bacterial populations;
2) precipitation of extracellular polysaccharides formed by oral streptococci;
3) precipitation of salivary glycoproteins during bacterial degradation. In the process of precipitation of salivary proteins, a lot important remove the activity of acid-forming bacteria and salivary calcium.
7. Physical properties of dental plaque. ZN is resistant to washing off with saliva and rinsing the mouth. This is explained by the fact that its surface is covered with a mucous semi-permeable mucoid gel. The mucoid film also, to a certain extent, prevents the neutralizing effect of saliva on ZN bacteria. It is insoluble in most reagents and is to some extent a barrier that protects the enamel. Salivary mucin and salivary corpuscles are deposited on the tooth surface and inhibit the remineralization process. Perhaps this effect is associated with the production of acid on the enamel surface during the breakdown of sugar or with the synthesis of large quantities of intra- and extracellular polysaccharides by ZN bacteria.
8. Microorganisms of dental plaque. ZN is an accumulation of microorganisms different types, incorporated into the matrix. In 1 mg of substance ZN there are 500×10 6 microbial cells.
Of these, more than 70% are streptococci, 15% are Veillonella and Neisseria, the rest of the flora is represented by lactobacilli, leptotrichia, staphylococci, fusobacteria, actinomycetes, and occasionally yeast-like fungi Candida albicans.
In the microbiocenosis of ZN, according to various studies, the ratios between bacteria are as follows: facultative streptococci - 27%, facultative diphtheroids - 23%, anaerobic diphtheroids - 18%, peptostreptococci - 13%, veillonella - 6%, bacteroides - 4%, fusobacteria - 4 %, Neisseria - 3%, Vibrios - 2%.
Six species of fungi were also found in the plaque.
The microbial flora of ZN is variable both quantitatively and qualitatively.
Thus, one- and two-day MN consists predominantly of micrococci, while in 3-4-day samples filamentous forms appear (and from the 5th day begin to predominate).
The number of different types of microorganisms in MN and saliva is not the same. Thus, there is little S. salivarius in plaque (about 1%), while there are many of these cocci in saliva; it also contains about 100 times less lactobacilli than saliva.
ZN microorganisms are better cultivated under anaerobic conditions, which indicates low oxygen tension in the deep layers of plaque. Nutrients for bacterial growth appear to come from outside. Dental tissues by themselves do not support the growth of microorganisms.
In ZN, most bacteria are acid-forming. There are also proteolytic bacteria, but their activity is relatively low.
9. Cariogenicity of dental plaque*. ZN does not form without microorganisms, therefore its cariogenicity is associated with the cariogenic bacteria present in it, which produce a significant amount of acids. Most bacteria in the MN (and especially cariogenic ones) are capable of synthesizing iodophilic polysaccharides, which are identified as intracellular types of glycogen. During caries, bacteria multiply and produce hyaluronidase, which, as is known, can actively affect the permeability of enamel. Cariogenic plaque bacteria are also capable of synthesizing enzymes that break down glycoproteins. It has been established that the higher the rate of formation of tumors, the more pronounced cariogenic effect it has.
When studying the cariogenicity of dental plaque, a large number of streptococci, actinomycetes, and veillonella were isolated. Of the streptococci, S. mutans and S. sanguis predominated, and fusobacteria and lactobacilli were almost not detected.
S.mutans plays the biggest role in the development of caries. It has been established that, as a rule, caries develops in children if the flora is dominated by S. mutans, which is isolated in the places of the most frequent localization of caries (proximal surfaces of the first upper premolars). Currently, five serotypes of S.mutans (a, b, c, d, e) have been identified, which are unevenly distributed among the world's population. S. mutans selectively adsorbs to tooth surfaces. There are especially many of these bacteria in the fissure area and on the proximal surfaces of the teeth. Under experimental conditions, it has been shown that if this microorganism adheres to any one surface of the tooth, then after 3-6 months it spreads to others and at the same time is stably fixed in primary focus. It has been established that in those areas where carious lesions subsequently develop, 30% of the microflora consists of S.mutans: 20% in the affected area and 10% in the periphery.
S. sanguis is also often isolated. Unlike S. mutans, which is localized in fissures, S. sanguis usually adheres to smooth tooth surfaces.
The flora of ZN is influenced by fluoride contained in drinking water, to which various types of streptococci and bacteria that synthesize iodophilic polysaccharides are especially sensitive. To suppress the growth of bacteria, about 30-40 mg/l of fluorine is needed.
Thus, the flora of ZN is a dynamic ecological system, well adapted to the surrounding microflora. It is able to quickly recover after brushing its teeth, exhibiting high metabolic activity, especially in the presence of carbohydrates.
Lecture 5
Microflora of dental plaque
1. Definition of dental plaque. 2. Mechanisms of formation of dental plaques. 3. Factors in the formation of dental plaque. 4. The role of oral streptococci in the qualitative transition from dental plaque to dental plaque. 5. Localization of dental plaque. Features of microflora, role in pathology.
1. Definition of dental plaque. Dental plaque is an accumulation of bacteria in a matrix of organic substances, mainly proteins and polysaccharides, brought there by saliva and produced by the microorganisms themselves. Plaques are tightly attached to the surface of the teeth. Dental plaque is usually the result structural changes ZN is an amorphous substance that fits tightly to the surface of the tooth and has a porous structure, which allows saliva and liquid food components to penetrate into it. The accumulation of final metabolic products of microorganisms and mineral salts* in plaque slows down this diffusion, as its porosity disappears. As a result, a new formation arises - a dental plaque, which can only be removed by force and then not completely.
2. Mechanisms of formation of dental plaques. The formation of dental plaque on smooth surfaces has been extensively studied in vitro and in vivo. Their development follows the general bacterial sequence of microbial community formation in the oral ecosystem. The process of plaque formation begins after brushing the teeth with the interaction of salivary glycoproteins with the tooth surface, with the acidic groups of glycoproteins combining with calcium ions, and the basic groups interacting with hydroxyapatite phosphates. Thus, on the surface of the tooth, as shown in Lecture 3, a film consisting of organic macromolecules, called a pellicle, is formed. The main components of this film are components of saliva and gingival crevicular fluid, such as proteins (albumin, lysozyme, proline-rich proteins), glycoproteins (lactoferrin, IgA, IgG, amylase), phosphoproteins and lipids. Bacteria colonize the pellicle within the first 2-4 hours after brushing. The primary bacteria are streptococci and, to a lesser extent, neisseria and actinomycetes. During this period, bacteria are weakly bound to the film and can be quickly removed by a flow of saliva. After initial colonization, the most active species begin to grow rapidly, forming microcolonies that penetrate the extracellular matrix. Then the process of bacterial aggregation begins and at this stage the constituent components of saliva are connected.
The first microbial cells settle in the depressions on the tooth surface, where they multiply, after which they first fill all the depressions and then move to the smooth surface of the tooth. At this time, along with cocci, a large number of rods and filamentous forms of bacteria appear. Many microbial cells themselves are not able to attach directly to the enamel, but can settle on the surface of other bacteria that have already adhered, i.e. the coadhesion process is underway. The settling of cocci along the perimeter of filamentous bacteria leads to the formation of so-called “corn cobs”.
The adhesion process occurs very quickly: after 5 minutes, the number of bacterial cells per 1 cm 2 increases from 10 3 to 10 5 - 10 6. Subsequently, the adhesion rate decreases and remains stable for approximately 8 hours. After 1-2 days, the number of attached bacteria increases again, reaching a concentration of 10 7 - 10 8. A ZN is formed.
Hence, initial stages plaque formation is the process of formation of pronounced soft dental plaque, which forms more intensively with poor oral hygiene.
3. Factors in the formation of dental plaque. In the bacterial community of dental plaque there are complex, complementary and mutually exclusive relationships (coaggregation, production of antibacterial substances, changes in pH and ORP, competition for nutrients and cooperation). Thus, oxygen consumption by aerobic species promotes the colonization of obligate anaerobes, such as bacteroides and spirochetes (this phenomenon is observed after 1-2 weeks). If the dental plaque is not exposed to any external influences(mechanical removal), then the complexity of the microflora increases until the maximum concentration of the entire microbial community is established (after 2-3 weeks). During this period, an imbalance in the dental plaque ecosystem can already lead to the development of oral diseases. For example, unrestricted development of subgingival plaque in the absence of oral hygiene can cause gingivitis and subsequent colonization of the subgingival crevice by periodontal pathogens. In addition, the development of dental plaque is associated with certain external factors. Thus, high carbohydrate consumption can lead to more intense and rapid colonization of plaques by S. mutans and lactobacilli.
4. The role of oral streptococci in the qualitative transition from dental plaque to dental plaque. Oral streptococci play an important role in the formation of dental plaques. S.mutans is of particular importance, since these microorganisms actively form tumors, and then plaques on any surfaces. S.sanguis plays a certain role. Thus, during the first 8 hours, the number of S.sanguis cells in plaques is 15-35% of the total number of microbes, and by the second day - 70%; and only then their number decreases. S.salivarius is detected in plaques only during the first 15 minutes, its amount is insignificant (1%). There is an explanation for this phenomenon (S.salivarius, S.sanguis are acid-sensitive streptococci).
Intense and rapid consumption (consumption) of carbohydrates leads to sharp decline Plaque pH. This creates conditions for a decrease in the proportion of acid-sensitive bacteria, such as S.sanguis, S.mitis, S.oralis and an increase in the number of S.mutans and lactobacilli. Such populations prepare the surface for dental caries. An increase in the number of S. mutans and lactobacilli leads to the production of acid at a high rate, increasing the demineralization of teeth. Then they are joined by veillonella, corynebacteria and actinomycetes. On the 9-11th day, fusiform bacteria (bacteroides) appear, the number of which increases rapidly.
Thus, during the formation of plaques, aerobic and facultative anaerobic microflora initially prevail, which sharply reduces the redox potential in this area, thereby creating conditions for the development of strict anaerobes.
5. Localization of dental plaque. Features of microflora, role in pathology. There are supra- and subgingival plaques. The former are of pathogenetic importance in the development of dental caries, the latter - in the development of pathological processes in the periodontium. The microflora of plaques on the teeth of the upper and lower jaws differs in composition: on dental plaques upper jaw Streptococci and lactobacilli are more common; Veillonella and filamentous bacteria live on the lower plaques. Actinomycetes are isolated from plaques on both jaws in equal numbers. It is possible that this distribution of microflora is explained by different pH values of the environment.
Plaque formation on the surface of fissures and interdental spaces occurs differently. Primary colonization proceeds very quickly and reaches its maximum already on the first day. Spread over the tooth surface occurs from the interdental spaces and gingival grooves; the growth of colonies is similar to the development of the latter on agar. Subsequently, the number of bacterial cells remains constant for a long time. In plaques of fissures and interdental spaces, gram-positive cocci and rods predominate, and anaerobes are absent. Thus, there is no replacement of aerobic microorganisms with anaerobic microflora, which is observed in plaques on the smooth surface of teeth.
With repeated periodic examinations of various plaques in the same person, large differences in the composition of the secreted microflora are observed. Microbes found in some plaques may not be found in others. A white spot appears under the plaques (white spot stage according to the classification morphological changes dental tissues during the formation of caries). The ultrastructure of the tooth in the area of white carious spots is always uneven, as if loosened. There is always a large number of bacteria on the surface; they adhere to the organic layer of enamel.
In persons with multiple caries, there is an increase in the biochemical activity of streptococci and lactobacilli located on the surface of the teeth. Therefore, high enzymatic activity of microorganisms should be regarded as caries susceptibility. The occurrence of initial caries is often associated with poor oral hygiene, when microorganisms are tightly fixed on the pellicle, forming plaque, which, under certain conditions, participates in the formation of dental plaque. Under dental plaque, the pH changes to critical level(4.5). It is this level of hydrogen ions that leads to the dissolution of the hydroxyapatite crystal in the least stable areas of the enamel; acids penetrate into the subsurface layer of enamel and cause its demineralization. When de- and remineralization is in balance, the carious process in the tooth enamel does not occur. If the balance is disturbed, when demineralization processes predominate, caries occurs in the white spot stage, and the process may not stop there and serve as a starting point for the formation of carious cavities.
Lecture 6
Lecture 7
Lecture 8
Lecture 9
Lecture 10
Lecture 11
Lecture 12
Lecture 13
Lecture 14
· Preface
· Lecture 1
· Normal oral microflora
· Lecture 2
· Microbiocenoses of individual biotopes of the oral cavity
· Lecture 3
· Microbial ecology of the oral cavity
· Lecture 4
· Microflora of dental plaque
· Lecture 5
· Microflora of dental plaque
· Lecture 6
· The role of microorganisms in the occurrence of caries
· Lecture 7
· Microbial flora in pathological processes in the oral cavity
· Lecture 8
· Microflora in periodontal diseases. Periodontopathogenic microbial species
· Lecture 9
· Microbial flora of the oral cavity and inflammatory processes in the maxillofacial area
· Lecture 10
· Microbial flora in inflammation of the oral mucosa
· Lecture 11
· Actinomycetes of the oral cavity. Role in pathology
· Lecture 12
· Mechanisms of oral immunity
· Lecture 13
· Disturbances in the microflora of the oral cavity. Dysbacteriosis
· Lecture 14
· Candida: ecology, morphofunctional characteristics and pathogenicity factors, characteristics of immunity
Microflora of the oral cavity: norm and pathology
Zelenova E.G., Zaslavskaya M.I., Salina E.V., Rassanov S.P.
Ecology of health: We are aware of the importance of intestinal microflora. But we know much less about the importance of oral microflora. Today I will talk about the non-dental influences of oral bacteria, how oral microflora affects headaches, cancer, bad breath and even the health of the heart and blood vessels.
We are aware of the importance of intestinal microflora.But we know much less about the importance of oral microflora. Today I will talk about the non-dental influences of oral bacteria, how oral microflora affects headaches, cancer, bad breath and even the health of the heart and blood vessels.
I’ll also tell you what else, in addition to brushing your teeth, can help our oral microflora and how normalization of nutrition contributes to the self-cleaning of the oral cavity, I will also talk about probiotics for the mouth).
Microflora of the oral cavity.
The human oral cavity is a unique ecological system for a wide variety of microorganisms that form a permanent microflora. The wealth of food resources, constant humidity, optimal pH and temperature create favorable conditions for the adhesion, colonization and reproduction of various microbial species.
Many opportunistic microorganisms from the normal microflora play a significant role in the etiology and pathogenesis of caries, periodontal diseases and oral mucosa. The microflora of the oral cavity takes part in the primary processes of food digestion and absorption useful substances and synthesis of vitamins.
It is also necessary to maintain the proper functioning of the immune system and protect the body from fungal, viral and bacterial infections. A little information about its typical inhabitants (you can skip it).
According to a study by scientists at the University of Buffalo (New York), 80-90% of cases of bad breath - halitosis - are responsible for the bacteria Solobacterium moorei, which produces foul-smelling compounds and fatty acids, living on the surface of the tongue, as well as Lactobacillus casei. Let us also note the bacterium Porphyromonas gingivalis - it causes periodontal disease and is also “responsible” for the body’s resistance to antibiotics.
In advanced cases it displaces beneficial bacteria and settles in their place, causing gum disease and ultimately tooth loss. Treponema denticola bacterium in case of insufficient hygiene oral cavity can greatly harm the gums, multiplying in places between the surface of the tooth and the gum. This bacterium is related to Treponema pallidum, which causes syphilis.
Approximately 30 - 60% of the total microflora of the oral cavity are facultative and obligate anaerobic streptococci. Streptococci are members of the Streptococcaceae family. The taxonomy of streptococci is currently not well established.
According to the identification of bacteria by Bergey (1997), based on physiological and biochemical properties, the genus Streptococcus is divided into 38 species, approximately half of this number belongs to the normal microflora of the oral cavity. The most typical types of oral streptococci are: Str. mutans, Str. mitis, Str. sanguis, etc. Moreover, various types of streptococci occupy a certain niche, for example, Str. Mitior is tropic to the epithelium of the cheeks, Str. salivarius - to the papillae of the tongue, Str. sangius and Str. mutans - to the surface of the teeth.
Back in 1970, it was found that the bacterium Streptococcus salivarius is one of the first to colonize the sterile mouth of a newborn. This happens as the baby passes through the birth canal. 34 years later, a large study of the microflora of the ENT organs in schoolchildren found that in children who do NOT suffer from acute respiratory infections, this very strain of streptococcus is present on the mucous membranes, actively producing the bactericidal factor (BLIS), which limits the proliferation of other bacteria.
But the bacterium Streptococcus mutans, which forms a film on the surface of teeth and can corrode tooth enamel and dentin, which leads to caries, the advanced forms of which can lead to pain, tooth loss, and sometimes gum infections.
Veillonella (often spelled "veillonella") are strictly anaerobic, nonmotile, gram-negative small coccobacteria; do not form a dispute; belong to the family Acidaminococcaceae. They ferment acetic, pyruvic and lactic acids well to carbon dioxide and water and thus neutralize the acidic metabolic products of other bacteria, which allows them to be considered as antagonists of cariogenic bacteria.
In addition to the oral cavity, Veillonella also inhabit the mucous membrane of the digestive tract. The pathogenic role of Veillonella in the development of oral diseases has not been proven. However, they can cause meningitis, endocarditis, and bacteremia. In the oral cavity, Veillonella are represented by the species Veillonella parvula and V. Alcalescens. But the bacterium Veillonella alcalescens lives not only in the mouth, but also in the respiratory and digestive tract of humans. It belongs to the aggressive species of the Veillonella family and causes infectious diseases.
Bacteria of the genera Propionibacterium, Corynebacterium and Eubacterium are often called “diphtheroids,” although this is more of a historical term. These three genera of bacteria currently belong to different families - Propionibacteriaceae, Corynebacteriacea and Eubacteriaceae. All of them actively reduce molecular oxygen during their life activity and synthesize vitamin K, which contributes to the development of obligate anaerobes.
It is believed that some types of corynebacteria can cause purulent inflammation. More strongly pathogenic properties are expressed in Propionibacterium and Eubacterium - they produce enzymes that attack the tissues of the macroorganism; these bacteria are often isolated in cases of pulpitis, periodontitis and other diseases.
Lactobacilli (family Lactobacillaceae) are strict or facultative anaerobes; More than 10 species live in the oral cavity (Lactobacilluscasei, L. acidophylius, L. salivarius, etc.). Lactobacilli easily form biofilms in the oral cavity. The active life of these microorganisms creates an environment favorable for the development of normal microflora.
Lactobacilli ferment carbohydrates with the formation of lactic acid, lower the pH of the environment, and on the one hand prevent the development of pathogenic, putrefactive and gas-forming microflora, but on the other hand contribute to the development of caries. Most researchers believe that lactobacilli are non-pathogenic for humans, but in the literature there are sometimes reports that in weakened people, certain types of lactobacilli can cause bacteremia, infective endocarditis, peritonitis, stomatitis and some other pathologies.
Rod-shaped lactobacilli constantly grow in a certain amount in a healthy oral cavity. Like streptococci, they are producers of lactic acid. Under aerobic conditions, lactobacilli grow much worse than under anaerobic conditions, since they produce hydrogen peroxide and do not form catalase.
Due to the formation of a large amount of lactic acid during the life of lactobacilli, they inhibit the growth (are antagonists) of other microorganisms: staphylococci. intestinal, typhoid and dysentery bacilli. The number of lactobacilli in the oral cavity during dental caries increases significantly depending on the size of the carious lesions. To assess the “activity” of the carious process, a “lactobacillentest” (determining the number of lactobacilli) is proposed.
Bifidobacteria (genus Bifidobacterium, family Actinomycetacea) are non-motile anaerobic gram-positive rods that can sometimes branch. Taxonomically they are very close to actinomycetes. In addition to the oral cavity, bifidobacteria also inhabit the intestines.
Bifidobacteria ferment various carbohydrates to form organic acids, and also produce B vitamins and antimicrobial substances that inhibit the growth of pathogenic and conditionally pathogenic microorganisms. In addition, they easily bind to epithelial cell receptors and form a biofilm, thereby preventing the colonization of the epithelium by pathogenic bacteria.
Dysbacteriosis of the oral cavity.
At the first stage of development of dysbacteriosis, there is an increase in the number of one or more species pathogenic organisms in the mouth. This is called a dysbiotic shift, and there are no manifestations. At the next stage, the number of lactobacilli decreases and barely noticeable manifestations appear.
At stage 3, instead of the lactobacilli necessary for the body, a large number of pathogenic microorganisms appear. During stage 4, yeast-like fungi actively multiply. In the last two stages of the disease, ulcers, inflammation and excessive keratinization of the oral epithelium may occur.
With a dysbiotic shift (compensated dysbacteriosis), there are no symptoms and the disease can only be detected using laboratory methods. When diagnosing, the number of opportunistic organisms is determined, while the normal flora of the mouth is not affected. Symptoms of oral dysbiosis in the form of a burning sensation in the mouth, the appearance of halitosis or a metallic taste indicate subcompensated dysbiosis.
Studies reveal a reduced level of lactobacilli, an increased volume of pathogenic microflora and the presence of pathogenic microorganisms. The appearance of seizures, infections in the mouth, inflammation of the tongue, and gums indicates decompensated dysbacteriosis. As a result of all of the above, the patient develops periodontal disease, stomatitis, and periodontitis.
By neglecting these diseases, you can lose several teeth. It is also possible to develop an infection of the nasopharynx. In such situations, the normal flora disappears, and in its place the opportunistic flora increases.
Halitosis: bad breath.
Halitosis is a sign of certain diseases of the digestive system in humans and animals, accompanied by a pathological increase in the number anaerobic microorganisms in the oral cavity and bad breath. Halitosis, bad breath, bad breath, ozostomia, stomatodysody, fetor oris, fetor ex ore.
In general, the term halitosis was coined to promote Listerine as a mouthwash in 1920. Halitosis is not a disease, it is medical term to indicate bad breath. How to define it? You can ask those around you or lick your wrist and after a while smell the area.
You can scrape the plaque off your tongue with a spoon or floss (special thread) in the spaces between your teeth and also evaluate the smell. Perhaps the most reliable option is to put on a disposable mask and breathe into it for a minute. The smell under the mask will exactly match the one that others smell when communicating with you.
There are psychological nuances with bad breath, this is pseudohalitosis: the patient complains about the smell, those around him deny its presence; the condition improves with counseling. Halitophobia - the patient’s sensation of an unpleasant odor persists after successful treatment, but is not confirmed by examination.
The main and immediate cause of halitosis is an imbalance of the oral microflora. Normally, the oral cavity contains aerobic microflora, which suppresses the development of anaerobic microflora (Escherichia coli, Solobacterium moorei, some streptococci and a number of other gram-negative microorganisms).
Anaerobic microflora, the nutrient medium for which is a dense protein coating on the tongue, teeth and inner surface of the cheeks, produces volatile sulfur compounds: methyl mercaptan (pungent smell of feces, rotten cabbage), allyl mercaptan (smell of garlic), propyl mercaptan (pungent unpleasant smell), hydrogen sulfide ( smell rotten egg, feces), dimethyl sulfide (unpleasantly sweet smell of cabbage, sulfur, gasoline), dimethyl disulfide (pungent smell), carbon disulfide (weak pungent smell), and non-sulfur compounds: cadaverine (dead smell and smell of urine), methylamine, indole, skatole (smell of feces , naphthalene), putrescine (the smell of rotting meat), trimethylamine, dimethylamine (fishy, ammonia smell), ammonia (a strong unpleasant smell), and isovaleric acid(smell of sweat, rancid milk, spoiled cheese).
True halitosis can be physiological or pathological. Physiological halitosis is not accompanied by changes in the oral cavity. It includes bad breath that occurs after eating. Some foods can cause bad breath, such as onions or garlic. When food is digested, the molecules that make it up are absorbed by the body and then eliminated from it.
Some of these molecules, which have very characteristic and unpleasant odors, enter the lungs along with the bloodstream and are excreted when exhaled. Bad breath associated with decreased secretion of the salivary glands during sleep (morning halitosis) or during stress is also classified as physiological halitosis.
Pathological halitosis (oral and extraoral) is caused by pathological conditions oral cavity, upper gastrointestinal tract, and ENT organs. Bad breath often occurs in women during hormonal changes: in the premenstrual phase of the cycle, during pregnancy, during menopause.
There is evidence that ozostomy may occur when taking hormonal contraceptives. Halitosis is often polyetiological. In chronic tonsillitis and sinusitis, purulent discharge from the tonsils and nasal cavity drains onto the back of the tongue. Together with periodontal diseases and poor oral hygiene (particularly the tongue), this leads to bad breath.
Oral microflora and heart disease.
The connection between the general condition of the body and dental health has long been known. Cardiovascular diseases are more likely to occur in those who have oral diseases. Scientists at the Karolinska Institute (Sweden) have proven a direct connection between the number of teeth and the risk of death from coronary disease heart - it was seven times higher for those who had only 10 natural teeth or less than for people of the same age and sex with 25 teeth or more.
According to modern data, constantly persistent oral microbiota can cause the development of atherosclerosis in two ways: directly - bacteria penetrate the vascular endothelium through the bloodstream, causing endothelial dysfunction, inflammation and atherosclerosis, and/or indirectly - through stimulating the production of mediators with atherogenic and pro-inflammatory systemic effects.
Modern research convincingly demonstrates the presence of a close relationship between the state of the oral microflora and the risk of developing pathologies with a systemic inflammatory component, such as cardiovascular diseases (CVD) (Amano A., Inaba H., 2012), diabetes mellitus (DM) (Preshaw P.M. et al., 2012), obesity (Pischon N. et al., 2007) and metabolic syndrome (MS) (Marchetti E. et al., 2012).
In a systematic review, L.L. Humphrey et al (2008) showed that periodontal diseases are a source chronic inflammation and act as an independent risk factor for coronary heart disease (CHD). For this reason, in many countries around the world, constant search common etiological and pathogenetic factors in the development of these disorders, which will improve the effectiveness of diagnostic and therapeutic strategies.
Of unconditional interest are data confirming the presence of bacterial microflora of the oral cavity in the blood and atheromatous plaques of blood vessels. Examining the DNA of periodontopathogenic flora in samples of plaques of the carotid artery of patients with atheroma of the carotid artery, T. forsynthensis was determined in 79% of samples, F. nucleatum - in 63% of samples, P. intermedia - in 53% of samples, P. gingivalis - in 37% of samples and A. actinomycetemcomitans - in 5% of samples.
A large number of periodontopathogenic microflora (Streptococcus mutans, Streptococcus sanguinis, A. actinomycetemcomitans, P. gingivalis and T. denticola) were identified in samples of aortic aneurysm and heart valve. However, it remains unclear whether the presence of periodontopathogenic microflora in atherosclerotic lesions is a factor that directly initiates the development of atherosclerosis, or a factor that has an indirect effect, aggravating the pathogenesis of the disease.
Recent studies indicate direct impact bacteria on endothelial cells of blood vessels. Infected P. gingivalis bacteria have been found to exhibit the ability to induce their uptake by macrophages and stimulate the formation of foam cells in the presence of low-density lipoprotein (LDL) in vitro.
Moreover, some bacterial species can penetrate and persist within aortic endothelial cells in vitro. Moreover, as studies have shown, P. gingivalis exhibits the ability to replicate intracellularly inside the autophagosome. The ability of P. gingivalis, as well as other periodontopathogenic bacteria, to persist intracellularly can initiate the development of secondary chronic infection, which, in turn, leads to further worsening of atherosclerosis.
Periodontopathogenic microflora is a key source of local and systemic chronic inflammation, and also acts as an independent risk factor for coronary heart disease (CHD). Studying the presence of various types of periodontopathogenic microflora in blood vessels in ischemic heart disease allowed us to conclude that the level of detection of their DNA reaches 100% in tissue samples of atherosclerotic plaques of the coronary arteries.
Migraine and the oral cavity.
Scientists have discovered a connection between migraines and bacteria that live in the mouth. As it turns out, migraines can be caused by the nitric oxide they produce. Migraine is a disease whose most characteristic symptom is a headache of unknown origin. Scientists from the University of California at San Diego noted that, according to statistics, 80% of patients who took nitrate-containing drugs for the treatment of cardiovascular diseases complain of migraines.
According to scientists, pain is caused not by nitrates themselves, but by nitric oxide NO, into which nitrates are converted in the body. But, as the researchers write, nitrates themselves will not turn into nitric oxide - our cells cannot do that. But the bacteria that live in our oral cavity can do this. Perhaps these bacteria are our symbionts and are beneficial, having a positive effect on the cardiovascular system.
The analysis showed that those subjects who suffered from migraines had more bacteria in their mouths that convert nitrates into nitric oxide than those who did not complain of headaches. The difference is not very big, about 20%, but, according to scientists, it cannot be neglected. The researchers believe that it is necessary to continue research in this direction and find out the role of bacteria living in the mouth in the occurrence of migraines.
Oral cancer and bacteria.
Oral microflora is not a cause of cancer, but can aggravate the progression of some cancers of the human digestive tract. This is cancer of the intestines and esophagus. Oral bacteria can provoke the development of malignant tumors of the large intestine. The study was published in the journal Cell Host & Microbe: doctors discovered that fusobacteria settle not on healthy tissues, but on colorectal tumors, and multiply there, which contributes to the acceleration of the development of the disease.
The microbes are believed to reach colon tissue through the bloodstream. The reason that fusobacteria prefer cancerous tumors is that the Fap2 protein, located on the surface of the former, recognizes the Gal-GalNac carbohydrate in the latter. But the bacterium P. gingivalis may become a new risk factor for squamous cell carcinoma of the esophagus, and may also serve as a prognostic biomarker for this type of cancer.
The bacterium Porphyromonas gingivalis infects the epithelium of patients with squamous cell carcinoma of the esophagus, is associated with the progression of a malignant tumor and is, at a minimum, a biomarker for the presence of this disease. Therefore, researchers recommend that people who have increased risk developing esophageal cancer, or having already received this diagnosis, make efforts to destroy or strongly suppress this bacterium in the oral cavity and throughout the body.
However, scientists have not yet established the reason for the large accumulation of bacteria in cancerous tumor. Either, as some researchers believe, the infection causes the development of a malignant tumor, or, as other scientists think, a malignant tumor is a favorable environment for the existence and development of bacteria. In any case, the presence of bacteria in the tumor, as has been proven by statistical data, worsens the prognosis of the disease.
Tips for normalizing the microflora of the oral cavity.
The advice is simple: do not feed bad microflora and do not kill good ones. Bad microflora occurs for two reasons: you feed it or you destroy it good microflora. Bad microflora grows if there is food for it - leftover food, especially carbohydrates. Cleaning the oral cavity and self-cleaning of the oral cavity will help us cope with this problem.
Self-cleaning of the oral cavity is a condition for healthy microflora.
Self-cleaning is understood as the constant ability of the oral cavity to cleanse its organs of detritus, food debris, and microflora. The main role in self-cleaning of the oral cavity is played by salivary glands, providing adequate secretion volume, flow and quality of saliva necessary for the formation of a food bolus that is convenient for chewing and swallowing. Movement is also important for effective self-cleaning. lower jaw, tongue, correct structure of the dental system.
Self-cleaning of the oral cavity is natural process liberation from food debris and detritus. It is carried out through the act of swallowing, the movement of the lips, tongue, cheeks, jaws and the flow of saliva. The process of self-cleaning should be considered as the most important function of the oral cavity, playing an important role in the prevention of dental caries and marginal periodontal diseases, since it removes the substrate for the development of conditionally pathogenic flora.
In modern humans, self-cleaning of the oral cavity is difficult. This is due to the nature of the food, a significant part of which is very soft and easily accumulates in retention points of the oral cavity: interdental spaces, retromolar triangle, gingival groove, in the cervical area of the teeth, carious cavities.
As a result of this, on solid and soft tissues sticky food debris accumulates, which is a good breeding ground for the constantly adapting microflora of the oral cavity, which is actively involved in the formation of secondary acquired structures.
The number of meals (any amount) has an important influence on the self-cleaning of the oral cavity. Normally, the self-cleaning system copes with only 4, maximum 5 meals. When they increase (including fruit or kefir), the self-cleaning system of the oral cavity does not work adequately. Therefore, 2-3 meals with clean intervals is a very important rule for healthy oral microflora.
Studies have shown that caries is accompanied by a decrease in salivation by 25%. A decrease in the level of saliva secretion is an unfavorable factor, since a decrease in saliva flow leads to a deterioration in mechanical and chemical cleansing of the oral cavity due to the fact that there is not enough saliva to remove food debris, detritus, and microbial mass.
These factors also negatively affect the processes of mineralization in the oral cavity, since its level depends on washing the teeth with saliva. In addition, deterioration in self-cleaning of the oral cavity leads to a decrease in the intensity of mineralization processes in the oral cavity and the creation of favorable conditions for the development of microflora in it.
Antibacterial factors in the oral cavity are represented by lysozyme, lactoperoxidase and other protein substances. They have bacteriological and bacteriostatic properties, due to which their protective function is carried out. The sources of these substances are the salivary glands and gingival fluid.
Self-cleaning of the oral cavity.
The advanced cleaning formula is as follows: brush your teeth + floss daily + brush your tongue in the evening + rinse your mouth after each meal with plain water.
Use dental floss. The study showed that the use of dental floss (floss) as a means of daily personal oral hygiene helps to completely eliminate bacteremia (bacteria in the blood) in patients. However, in ≈86% of these same patients, after stopping the use of dental floss, bacteremia was detected already on days 1–4.
Cleaning the tongue. There are various brushes and scrapers for the tongue, but patients are not sufficiently aware of the aspects of tongue hygiene, the selection of special products, and its use. proper cleaning. Mentions of tongue scrapers date back to the 11th century. The first scientific recommendations for the use of mechanical means of cleaning the tongue and medicinal treatment were formulated in the 15th century by the Armenian physician Amirdovlat Amasiatsi in the book “Unnecessary for the Ignorant.”
The first tongue scrapers discovered by scientists belong to the Qin Dynasty. Scrapers, spoons, and loop-shaped tongue brushes dating from the 15th to 19th centuries and made in various European countries were discovered. They are made of various materials: ivory, tortoiseshell, silver, gold. In the 20th century, a plastic tongue scraper was released. In the 20th–21st centuries, the production of tongue brushes with small flat bristles began.
A special brush is adapted to clean the surface of the tongue. The structure of its bristles allows the hairs to penetrate into the space between the filiform papillae. A wide working surface, a comfortable shape and a low bristle profile provide effective access of the brush to the most pathogenically significant areas of the dorsal surface, located at the root of the tongue, without provoking discomfort and a gag reflex.
Another innovation is electric tongue brushes. Cleaning your tongue is an essential part of oral hygiene. According to the American Dental Association, regular use of this procedure leads to a 33% reduction in plaque formation. Particular attention should be paid to tongue hygiene in case of folded and geographical tongue.
Plaque accumulates in the depths of the folds - a favorable factor for the proliferation of anaerobic bacteria. To remove it efficiently, you need to use tongue brushes. Usage special gel makes cleaning easier by softening plaque. By cleaning the tongue, halitosis is eliminated, the total number of bacteria in the oral cavity is reduced, which has a beneficial effect on the health of periodontal tissues. The easiest way to clean your tongue is with a piece of regular gauze.
Food and dental microflora.
In modern man, due to the increasing reduction of the dentofacial apparatus, massive damage to teeth by caries, periodontal diseases, anomalies and deformations, self-cleaning of the oral cavity is difficult. This is also predisposed by the nature of the food, a significant part of which is sticky, soft, viscous, easily accumulating in numerous retention points of the oral cavity.
A decrease in self-cleaning is facilitated by the chewing laziness of modern man, who prefers ground, twisted, soft food, which, in turn, due to a decrease adaptive capabilities dental system leads to rapid development of microflora with all the ensuing consequences.
The composition and properties of food are a powerful factor in regulating the activity of the salivary glands and the composition of saliva. Rough fibrous foods, especially spicy, sour, sweet and sour foods stimulate salivation. This important physiological aspect is influenced by such qualities of food products as viscosity, hardness, dryness, acidity, salinity, causticity, and pungency.
Nutrition, in addition to performing its main function, also acts as a factor in self-cleaning and training of the oral organs, which is directly related to the act of chewing carried out by the dental system. Self-cleaning of the oral cavity is a natural process of getting rid of food debris.
According to research in the field of microbiology, hundreds of different types of microscopic living organisms are simultaneously present in the mouth of a healthy person. This is a special ecosystem that is essential for human life. Microbiology divides the entire set of organisms in the oral cavity into groups:
- autochthonous microorganisms – present in the oral cavity of humans as a biological species;
- allochthonous - organisms that migrated into the oral cavity from other organs, for example, the nasopharynx or intestines;
- imported - microflora of the oral cavity that comes from the environment.
The main role among the microbiota is played by autochthonous (resident) organisms. They are divided into:
- obligate microflora, constantly present in the oral cavity;
- facultative, which includes conditional pathogens.
Microscopic organisms settle in colonies on the mucous membrane and surface of the teeth. The study of the mechanisms of interaction between various forms of biota is the basis for the development of dental treatment methods.
Composition of normal oral microflora:
- Bacteria are the predominant form. They are most numerous in the morning on an empty stomach and least immediately after eating. The largest resident group is cocci.
- Viruses.
- Mushrooms.
- Protozoa.
In varying quantities, the resident microflora of the oral cavity constantly contains the following forms:
Factors that upset the balance
Various microorganisms, interacting with each other, create a certain balance in their ecosystem. Oral microbiology calls the departure from this equilibrium state dysbiosis. The destruction of the balance of the microflora of the oral cavity is affected by:
- chronic oral diseases;
- immunodeficiency;
- irregular nutrition, lack of sufficient quantities of essential elements in food;
- lack of vitamins;
- disturbances in the gastrointestinal tract;
- high content of harmful substances in the environment;
- quality of functioning of the salivary glands;
- developmental anomalies of the maxillofacial apparatus;
- smoking and alcohol abuse.
Concept of oral dysbiosis
The normal oral microflora is a dynamic balance of many microscopic organisms that interact with each other. Each type of autochthonous (resistant) bacteria or fungi performs its own specific function that is beneficial to humans. For example, lactobacilli and staphylococci break down carbohydrates and participate in the initial phase of the digestive process.
When the population of a particular species increases, an imbalance occurs, and bacteria move from being friendly to humans into the category of pathogens. Thus, colonies of staphylococci cause caries. The microbiology of the oral cavity with such an imbalance is called dysbiosis. This disease is the root cause of most dental problems.
Causes
Dysbacteriosis is caused by external reasons, namely:
- Due to intestinal dysbiosis. Under normal conditions, the intestinal microbiota promotes the absorption of vitamins A, E, D and produces vitamin B. With dysbacteriosis, vitamin deficiency occurs, which negatively affects the oral cavity.
- The same processes occur in chronic gastrointestinal diseases.
- Long-term or uncontrolled use of drugs containing antibiotics.
- The use of certain drugs to disinfect the oral cavity.
Symptoms
There are no specific symptoms of oral dysbiosis. All symptoms associated with this process are signs of diseases resulting from an imbalance of microflora. Summarizing them, we can form the following list:
- white coating on the tongue, gums, throat;
- herpes;
- inflammatory processes of teeth and gums;
- bad breath;
- mouth ulcers;
- cracks on the lips.
Restoration of normal microflora
The goal of treating dysbiosis is to restore the balance of oral microflora. To do this, it is necessary to establish and eliminate what caused the disease. Diagnostic methods are based on advances in microbiology and involve analyzing the microbiota of a smear taken from the oral mucosa.
The complex of therapeutic measures includes:
- dental sanitation - checking the condition of the mouth, removing tartar, eliminating all identified inflammations;
- vitamin therapy;
- a course of probiotics that stimulate “good” bacteria;
- quitting smoking and alcohol;
- normalization of diet;
- antiseptic treatment of the mouth;
- course of immunostimulants;
- antifungal therapy;
- in advanced stages - taking antibiotics;
- mouth and teeth care.
Preventive measures
Preventive measures will help to stably maintain the balance of oral microflora:
- It is unacceptable to use antibiotics without a doctor’s prescription;
- refuse food products containing toxic substances and components that irritate the oral mucosa;
- a balanced diet, including vitamins and microelements, avoiding excess sweets;
- taking care of the normal functioning of the gastrointestinal tract;
- regular oral hygiene.
