Where did caries come from and can it be defeated?

2024 Author: Seth Attwood | [email protected]. Last modified: 2023-12-16 15:55

Tooth decay is an infection that almost all inhabitants of 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.

Tooth structure Hard but vulnerable The enamel that forms the crown of the tooth is the hardest substance in the human body. Nevertheless, it cannot withstand the chemical attack of the waste products of S. mutans streptococci.

The fact that the teeth were attacked by a persistent and difficult to destroy infection is partly to blame for humanity itself.

Today, most dentists adhere to the version 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, abandoning 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.

The 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 discovered several other species of streptococci and lactobacilli, continuing the process, and, in addition, the type of actinomycetes responsible for tooth root caries.

The fact that streptococci are the cause of the unpleasant disease is quite logical. Microbes of this genus have been present in the digestive system of humans and animals for thousands of years, usually without causing any harm.

To maintain their own life, streptococci use carbohydrates from our food, decomposing them at a record rate compared to other bacteria, and after that, leaving alcohols, aldehydes or acids.

With the advent of big cities and catering, carious bacteria took over more and more mouths, and Streptococcus achieved its triumph after the industrial revolution, when refined sugar, soft drinks and other foods high in sucrose - ideal for fast carbohydrate fermentation - became cheap and affordable. It was then that plaque became an ideal environment for parasitism for cariogenic microbes.

Destruction mechanism

To understand how caries appears, you first need to know that tooth enamel is about 95% composed of a mineral - calcium hydroxyapatite Ca10 (PO4) 6 (OH) 2. Its hexagonal crystals combine to form prisms and provide strength to bones and teeth. The enamel of just one incisor contains about 5 million mineral prisms.

Like all hydroxyl ("alkaline") minerals, hydroxyapatite is degraded by acids. This happens due to the violation of the notorious acid-base balance, known to everyone from advertising of 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 saliva. And without calcium, mineral prisms collapse like houses of cards. If the process is repeated, the acids attack the dentin located under the enamel. Then a carious cavity appears in the tooth - a cavity.

Simple organic acids such as acetic, lactic and citric acids are especially "scary". 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 even without oranges.

Plaque streptococci feed on the carbohydrates we eat, and aggressive acids are the by-product of their fermentation. The simpler the carbohydrate, the faster the acid is formed from it. This means that the more often we eat simple carbohydrates (glucose, fructose, sucrose), the more caries progresses.

The enamel that forms the crown of a tooth is the hardest substance in the human body. However, it cannot withstand the chemical attack of S. mutans streptococcus waste products.

Approximately the mechanism of the development of this disease was described by the American scientist-dentist Willoughby Miller at the end of the 19th century, calling it the chemical-parasitic theory. This means that, on the one hand, the appearance of caries is a chemical process, but without microbes-parasites it would not be so large-scale or would be completely neutralized.

According to the head of the Department of Caries Prevention at MGSU Edith Kuzmina, three reasons are to blame for the appearance of caries: plaque with bacteria, carbohydrate foods and poor stability of tooth enamel.

This means that there can be only three ways to fight tooth decay: eat as few simple sugars (easily fermented carbohydrates) as possible, make tooth enamel more resistant to decay, and, finally, rid your teeth of plaque, in which streptococci are hiding.

Bitter sweet truth

Of course, people knew for a long time that "sweets spoil their teeth", but it was possible to prove the role of diet in the occurrence of caries only when, in the course of numerous independent experiments, it was found that streptococci are present in dental plaque and in people free from caries.

The first step in proving sugar "guilt" was taken by Danish professor Frederik von der Fehr of the Royal College of Dentistry in Aarhus. In 1970, von der Fehr conducted an experiment in which a group of volunteers with good tooth enamel condition completely excluded oral hygiene - they did not brush or rinse their teeth after eating. Half of them also rinsed their mouths with a 50% sucrose solution several times a day.

Lack of hygiene increased the number of bacteria in plaque, but when comparing the condition 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 everyone appeared in the diet, now, according to dental surveys, most people in Russia and many other countries eat sweets every day. As Edith Kuzmina notes, it is not so much the amount of sweet eaten at a time that is important, but the frequency of its consumption.

Ideally, dentists advise eating sweets as little as possible and replacing fermentable sugars - glucose, sucrose, and fructose - with sorbitol, mannitol, and xylitol. These polyhydric alcohols have a sweet taste and are often used as sweeteners (for example, in diabetes), and carious streptococci simply cannot utilize them.

Natural xylitol is found in strawberries and carrots. And if you still cannot refuse sweet, then it is better to eat it not "alone", but together with other food - this reduces cariogenicity. The same sour apples, for example, require an abundant separation of saliva, and it dilutes and, having an alkaline reaction, partially neutralizes the acid formed in the mouth after the fermentation of sucrose and glucose.

Two-faced fluoride

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

For the first time, fluoride was massively added to milk for the prevention of caries in schools and kindergartens in Switzerland in 1953. After 60 years, 95% of the world's toothpastes 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 of these substances help protect teeth from tooth decay is very simple. Fluorine ions are introduced into the crystal lattice of mineral enamel prisms, after which its solubility in acids decreases.

"Harmful" hormone

Today, it is fairly well established that the prevalence of caries among men is, as a rule, 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. Then the researchers noticed that the rate of development of caries increases with increasing levels of estrogen in males, ovariectomized (deprived of ovaries) and normal females.

At the same time, the level of male hormones - androgens - did not show any particular effect on the condition of the teeth. Since then, dozens of studies have been conducted that have confirmed the relationship between the level of female hormones and the likelihood of developing tooth decay. The exact mechanism by which estrogens affect dental health has not yet been studied, but saliva is thought to contain estrogen-sensitive immunoreactive proteins that regulate the number of cariogenic microbes in the mouth.

On the other hand, it is because of the fluorides that a pea-sized amount of toothpaste is recommended, rather than the full-bristle-length sausages of a toothbrush, as shown in TV commercials. The main reason for this is the danger of fluorosis, or supersaturation of the enamel with fluorine.

The trick of fluoride is that if there is too much of it, it converts the hydroxyapatite of the enamel into another, more fragile mineral, and the teeth literally begin to crumble.

In this case, fluorides can enter the body not only with toothpaste - you just need to inhale them.

For example, in people living near active volcanoes and factories that produce hydrofluoric acid, fluorosis occurs three times more often: volcanic ash and industrial waste contain fluoride. For the first time, the Roman poet Mark Marziall spoke about this effect of "overdose" of fluorine, describing the teeth of the concubine of Alexander the Great as "speckled".

To preserve teeth and avoid their destruction from excess fluoride, it is enough just to follow the “pea rule” and not brush your teeth too often - two or three times a day is enough. Fluoridation has ardent opponents, who argue that toothpaste and fluoride-fortified milk - you can buy it in Russia - cause a whole bunch of dangerous diseases, including malignant tumors.

But such claims are not supported by any reliable data. Yes, fluoride and its compounds are really poisonous substances.

But here it's all about concentrations: even Paracelsus (Philip Aureol Theophrastus 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; It is only the dose that makes it one way or another”.

Fluoride poisoning requires literally eating a few tubes of toothpaste every day. As for milk with sodium fluoride, its daily requirement is a glass (200 ml), as indicated on the package.

However, fluoride toothpastes have an alternative. First of all, fluoride-free pastes that strengthen the enamel due to calcium or whole mineral molecules - artificial hydroxyapatite, intended for children who often swallow the paste, and people living at risk.

Vaccine against tooth decay

To invent a vaccine against caries, forcing the body to kill the pathogenic streptococci, is the cherished dream of many scientists.

Chinese researchers from the Institute of Virology in Wuheng came closest to ridding mankind of the sounds of a drill. In 2011, they announced a successful rat trial of a DNA combination vaccine.

Its essence is that in addition to the DNA of the streptococcus itself, it also contains the nucleic acid of another bacterium - Salmonella. The immune system reacts to salmonella more actively, straightening at the same time with cariogenic streptococcus.

But even if the vaccine against caries appears in the arsenal of dentists, we can hardly forget about fillings and dentures. As one of the world's leading epidemiologists, Daniel Smith of the Boston Foresight Institute, explains, the vaccine will only be really effective if it is inoculated in children between the ages of one and two - when the first baby teeth appear, but plaque - a community of bacteria - has not yet had time to form. …

There is another weakness in the tooth decay vaccine.

Even if she manages to overcome one type of streptococcus, which causes the first signs of the disease, other types of bacteria that are connected to tooth decay at different stages may well be retrained as initiators.

Therefore, dentists call caries an insidious infection, which can and should be fought with the traditional methods: follow the diet and regularly visit the dentist. Indeed, unlike sharks, which can renew several thousand teeth during their life, we humans lose precious teeth forever.