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Why mankind suffers from caries, and is it possible to deal with it

Почему человечество страдает от кариеса, и можно ли с этим бороться

Caries is a complex, slowly current pathological process in the hard tissues of the tooth, developing as a result of the complex effect of adverse external and internal factors. In the initial stage of development, caries is characterized by focal demineralization of the inorganic part of enamel and destruction of its organic matrix. Ultimately, this leads to the destruction of the hard tissues of the tooth with the formation of a cavity in the dentin, and in the absence of treatment, the occurrence of inflammatory complications of the pulp and periodontal.

Caries is an infection that almost all people on our planet are infected with today. According to epidemiologists, even in the Middle Ages, the prevalence of caries in Europe was three times less than modern. The reason for the victorious march of dental disease lies primarily in the fact that we eat.

The fact that the teeth attacked persistent and difficult to destroy the infection, partly to blame for humanity itself. Today, most dentists adhere to the theory that the cariogenic bacterium, Streptococcus mutans, migrated into the oral cavity from the stomach 10–15 thousand years ago, when the first tribes of our ancestors switched to agriculture and cattle breeding, abandoned hunting, and began to consume less protein (meat) and more carbohydrates (cereals, vegetables, and dairy products). Surprisingly, the infectious nature of caries was reliably established less than half a century ago.

Bacteria responsible for the development of the carious process were identified at the beginning of the 20th century. But, in addition to the initiator of the initial stage of caries, S. mutans, among the "provocateurs" scientists later also found several other types of streptococci and lactobacilli, continuing the process, and, in addition, the kind of actinomycetes responsible for caries of the tooth root. The fact that the cause of an unpleasant disease is just streptococci is quite logical. Microbes of this kind are present for thousands of years in the digestive system of humans and animals, usually without causing any harm.

To maintain their own life, streptococci use the carbohydrates of our food, decomposing them at a record speed compared to other bacteria, and then leaving alcohols, aldehydes or acids. With the advent of big cities and catering, the carious bacterium took more and more mouths, and streptococcus triumph reached after the industrial revolution, when refined sugars, soft drinks and other foods high in sucrose — ideal for fast fermentation of carbohydrate — became cheap and affordable. It was then that dental plaque for cariogenic microbes became the ideal medium for parasitism.

Destruction mechanism

Почему человечество страдает от кариеса, и можно ли с этим бороться

To understand how caries appears, first of all you need to know that tooth enamel consists of about 95% of the mineral, calcium hydroxyapatite Ca10 (PO4) 6 (OH) 2. Its hexagonal crystals are combined into prisms and provide the strength of bones and teeth. The enamel of only one cutter contains about 5 million mineral prisms.

Like all hydroxyl ("alkaline") minerals, hydroxyapatite is destroyed by the action of acids. This is due to the violation of the notorious acid-base balance, known to all for advertising chewing gum. When acid enters the mouth, for example with a sip of wine, our body tries to neutralize it, and calcium from the enamel migrates into the saliva. And without calcium, mineral prisms collapse like card houses. If the process is repeated, the acids attack the dentin under the enamel. Then a carious cavity appears in the tooth - a cavity.

Simple organic acids, such as acetic, lactic and citric, are especially “terrible”. Therefore, when we drink wine or eat an orange, the enamel of our teeth is doomed to partial destruction. But acids appear in the mouth and without oranges. Streptococci of plaque feed on the carbohydrates we eat, and the by-products of their fermentation are just aggressive acids. The simpler the carbohydrate, the faster the acid is formed from it. And this means that the more often we eat simple carbohydrates (glucose, fructose, sucrose), the more the caries progresses.

Approximately the mechanism of the development of this disease was described by the American dental scientist Willloby Miller at the end of the 19th century, calling it chemical-parasitic theory. This means that, on the one hand, the appearance of caries is a chemical process, but without parasitic microbes it would not be so large-scale or would be completely neutralized. According to Edith Kuzmin, head of the department of caries prevention at MSSU, there are three reasons for the appearance of caries: plaque with bacteria, carbohydrate food and poor resistance of tooth enamel.

This means that there can be only three ways to fight caries: eat as few simple sugars as possible (easily fermentable carbohydrates), make tooth enamel more resistant to destruction, and finally, save teeth from plaque, in which streptococci hide.

Bitter sweet truth

Of course, people knew for a long time that “sweet teeth deteriorate”, but it was possible to prove the role of diet in the appearance of caries only when, in the course of numerous independent experiments, it was found that streptococci are present in dental plaque in people free from caries. The first step in proving sugar "guilt" was made by Danish professor Frederick von der Fehr from the Royal College of Dentistry in Aarhus. In 1970, von der Fer conducted an experiment in which a group of volunteers with good dental enamel completely ruled out oral hygiene — they didn’t clean or rinse their teeth after eating.

Half of them also rinsed their mouth several times a day with a 50% sucrose solution. Lack of hygiene increased the number of bacteria in plaque, however, when comparing the state of the teeth of those who rinsed their mouth with a sweet solution, with the control group, more obvious signs of caries were found - demineralization of the enamel and the appearance of stains on it.

If earlier, for example, in the not-so-distant 18th century, sugar was an expensive product and not everybody appeared in the diet, now, according to dental surveys, most people in Russia and many other countries eat sweets daily. As Edith Kuzmina notes, it is important not so much the amount of sweet eaten at once, but the frequency of its consumption.

Ideally, dentists are advised to eat sweets as rarely as possible and replace fermentable sugars — glucose, sucrose, and fructose — with sorbitol, mannitol, and xylitol. These polyhydric alcohols have a sweet taste and are often used as sugar substitutes (for example, in diabetes), and carious streptococci simply cannot utilize them. Natural xylitol is found in strawberries and carrots. And if you reject the sweet, it still does not work, then it is better to eat it not “alone”, but together with other food - this reduces cariogenicity. The same sour apples, for example, require copious saliva, but it dilutes and, having an alkaline reaction, partially neutralizes the acid formed in the mouth after fermentation of sucrose and glucose.

Two-faced fluoride

Почему человечество страдает от кариеса, и можно ли с этим бороться

If the first way to fight tooth decay - to give up sweets - is not for everyone, then making tooth enamel more resistant to acids is much easier. Today, the only globally recognized and most effective way to strengthen enamel is still fluoridation.

For the first time massively adding fluoride to milk for the prevention of dental caries began in schools and kindergartens in Switzerland in 1953. After 60 years, 95% of the toothpastes in the world contain fluoride. If you read the composition of your toothpaste, you will most likely find sodium fluoride, monofluorophosphate or aminofluoride in it. Or maybe there will be several fluorides. The mechanism by which all these substances help protect teeth from caries is very simple. Fluorine ions are embedded in the crystal lattice of mineral enamel prisms, after which its solubility in acids decreases.

On the other hand, precisely because of fluoride, toothpaste is recommended to be used in quantities of the size of a pea, and not sausages the length of the entire bristles of a toothbrush, as shown in a television advertisement. The main reason for this is the danger of fluorosis, or enamel oversaturation with fluorine.

The cunning of fluorine lies in the fact that if there is too much of it, it turns enamel hydroxyapatite into another, more fragile mineral, and the teeth begin to literally crumble. At the same time, fluorides can enter the body not only with toothpaste, but simply inhale them. For example, people living near active volcanoes and plants producing hydrofluoric acid, fluorosis occurs three times more often: volcanic ash and waste products contain fluorides. For the first time, the Roman poet Mark Martialla spoke about this effect of “overdose” of fluorine, describing the teeth of the concubine of Alexander the Great as “speckled”.

To save teeth and avoid their destruction from an excess of fluorine, simply follow the “pea rule” and not brushing your teeth too often - two or three times a day is enough. Fluoridation has ardent opponents, claiming that toothpaste and milk enriched with fluoride - you can buy it in Russia - cause a whole bunch of dangerous diseases, including malignant tumors. But such statements are not supported by any reliable data. Yes, fluorine and its compounds are really toxic substances.

But it’s all a matter of concentration: even Paracelsus (Philip Aureol Theophrast Bombast von Hohenheim), the great medicus and alchemist of the Renaissance, formulated an aphorism that has not lost its relevance over the past five centuries: “Everything is poison and everything is medicine; only dose makes it one way or another. ” To get fluoride poisoning, you literally need to eat several tubes of toothpaste every day. As for milk with sodium fluoride, its daily rate is a glass (200 ml), as indicated on the package.

However, toothpaste with fluoride is an alternative. First of all, pastes without fluoride, strengthening enamel due to calcium or whole mineral molecules - artificial hydroxyapatite, intended for children, often swallowing the paste, and people living in the risk zone.

Vaccine against caries

To invent a vaccine against caries, forcing the body to kill pathogenic streptococci, is the cherished dream of many scientists. The closest thing for the deliverance of humanity from the drilling of the drill came Chinese researchers from the Institute of Virology in Wuhen. In 2011, they announced a successful trial in rats combined DNA vaccine. Its essence is that in addition to the Streptococcus DNA itself, it also contains the nucleic acid of another bacterium, Salmonella. Immunity reacts to salmonella more actively, cracking down at the same time on cariogenic streptococcus.

But even if the vaccination against caries also appears in the arsenal of dentists, we can hardly forget about fillings and dentures. As one of the leading epidemiologists in the world, Daniel Smith of the Boston Forsythe Institute, explains, the vaccine will really be effective only if children ages one to two years old are vaccinated - when the first baby teeth appear, but plaque - a community of bacteria - is not yet formed .

Vaccine against caries has another weak point. Even if she succeeds in overcoming one type of streptococcus, which causes the first signs of illness, other types of bacteria that are connected to the destruction of a tooth at different stages can easily be retrained as initiators. Therefore, dentists call caries an insidious infection, which can and should be dealt with in traditional ways for now: follow the diet and regularly visit the dentist. Indeed, unlike sharks, which in the course of life can renew several thousand teeth, we humans lose precious teeth forever.

"Harmful" hormone

Scientists have found that the prevalence of caries among men is usually lower than among women. This is due to the direct relationship between the level of estrogen in the blood and the microbial microflora of the oral cavity. The first direct correlations in experiments with rats were obtained in the middle of the last century at Indiana University. Researchers have noticed that the rate of caries development increases with increasing estrogen levels in males, as well as in females, both normal and ovariectomized (devoid of ovaries). At the same time, the level of male hormones - androgens - did not show any particular effect on the state of the teeth. Dozens of studies have confirmed the relationship of the level of female hormones and the likelihood of caries. So far, the exact mechanism of the effect of estrogen on dental health has not been studied, but it is assumed that saliva contains estrogen-sensitive immunoreactive proteins that regulate the amount of cariogenic microbes in the mouth.