2 hours ago
Martha Henriques
BBC Future
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Crowded, misaligned, riddled with cavities and inflamed gums, our teeth are infamous for their flaws.
The modern man is unique in that he must intervene every day to ensure that his teeth and gums do not get sick.
More than just toothache and gum pain, our oral health impacts everything from our diet to our overall well-being to the risk of death from all causes over the course of our lives. a given year.
This is because mouth diseases do not always stay in the mouth.
It is beginning to appear that there is a strong link between oral health and some of the world’s most pressing diseases, including cardiovascular disease, diabetes and Alzheimer’s disease, underscoring the role of the mouth as mirror of health and disease, and as a sentinel of our general well-being.
Unfortunately, perhaps the most telling characteristic of oral health is the one that is most often overlooked.
Generalized disease
Periodontitis, or gum disease, is the second most common oral disease following tooth decay. It affects more than 47% of adults over the age of 30.
After age 65, 64% have moderate or severe periodontitis. Globally, it is the eleventh most prevalent disease in the world.
Periodontitis is an infection that is not on the surface of the gums that you can see when you smile, but deep down.
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Regular visits to the dentist are essential for maintaining good oral health.
After an initial phase of superficial inflammation in the visible part of the gumline (gingivitis), the bacteria descend below the gum line into pockets near the root of the tooth where they erode the structures that hold the tooth in place.
Due to the hidden nature of periodontitis, many people who suffer from it do not know they have it until they have reached a very advanced stage. This disease has a genetic component and is also influenced by oral hygiene.
For most people, the disease is not visible until the age of 40 or 50, says Sim K. Singhrao, a senior researcher at the University of Central Lancashire Dental School in the UK.
By then, serious damage may have already undermined the architecture of the tooth, with the risk of losing it. In the meantime, the infection sent a constant trickle of bacteria, such as Treponema denticola and Porphyromonas gingivalis, into the bloodstream for decades.
Bacteria in the blood
It is this long-term presence of disease-causing bacteria in the gums and bloodstream that shapes our health far beyond the mouth.
“If you imagine the blood system as a bus, it will carry passengers, things like bacteria in the mouth, and it will go all over the body,” says Singhrao.
“Some will be triggered in the brain, others in the arteries, still others in the pancreas or the liver”.
When these organs have vulnerabilities or the microbes are not eliminated effectively, they cause inflammation and trigger or exacerbate other inflammatory diseases.
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Periodontitis affects 47% of adults over the age of 30.
In fact, periodontitis is linked to a list of some of the most common non-communicable diseases in the world: cardiovascular disease, diabetes, Alzheimer’s disease, obesity, various cancers, rheumatoid arthritis, Parkinson’s disease, pneumonia and pregnancy complications. .
Two-way relationship
For many of these pathologies, it is a two-way relationship. For example, periodontitis can aggravate conditions such as atherosclerosis, hardening of the walls of the arteries, and the presence of atherosclerosis also predisposes patients to periodontitis.
There have been no randomized controlled trials (RCTs), considered the gold standard of medical research, to investigate this relationship (it would be difficult to conduct them ethically, refusing to one group to treat his periodontitis for an extended period to see how it affects his atherosclerosis).
However, the bacteria responsible for periodontitis, which are usually found only in the mouth, have been discovered in atherosclerotic plaques.
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This is partly a genetic problem, but oral hygiene also plays a role.
Of all these chronic conditions, diabetes has the strongest bidirectional link with periodontitis.
People with type 2 diabetes have a three times higher risk of developing periodontitis than people without diabetes.
In people who have both type 2 diabetes and periodontitis, the infection worsens the body’s ability to control blood sugar.
But what is behind this link?
From the gums to the blood system
This is the constant passage of bacteria from the deep pockets of the gums into the bloodstream.
When the immune system detects bacteria or other pathogens, immune cells release a flood of cellular messenger molecules called inflammatory markers.
These inflammatory markers help the immune system attack and kill invading pathogens.
The occasional swelling and redness around a wound is the result of this effective inflammatory response.
In the short term, inflammatory markers are excellent guides for the immune system to identify the site of a probable infection.
But when these sentinels remain in the body, they cause a number of problems.
Most periodontitis-related conditions have a well-established inflammatory element.
For example, almost 30 years ago, an inflammatory marker called tumor necrosis factor alpha was revealed to increase insulin resistance in diabetics.
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The dentist should not only be consulted in case of severe pain, but it is important to have regular check-ups.
This discovery was quickly followed by that of a wave of other inflammatory markers that exacerbate both obesity and type 2 diabetes.
This dense web of inflammatory markers has prompted research aimed at treating diabetes by reducing chronic inflammation.
But the constant flow of bacteria from a hidden infection in the gums does the exact opposite.
“All inflammatory diseases are linked, they influence each other,” says Palle Holmstrup, professor emeritus at the department of dentistry at the University of Copenhagen.
“Periodontitis is one of the most common, if not the most common, inflammatory disease of the human body.”
“These are the same inflammatory mediators that are active in several types of inflammatory diseases: rheumatoid arthritis, heart disease, diabetes, etc. If you have periodontitis, you will have a higher level of low-grade systemic inflammation.”
Rat experiments
In humans, it is difficult to study directly how the treatment of periodontitis might relieve conditions such as diabetes, for the same ethical reasons as for atherosclerosis: a patient cannot be refused treatment for his disease, especially if it is suspected that it might aggravate his other conditions. This makes the study of this complex knot of related inflammatory diseases particularly challenging, and causal relationships difficult to pin down.
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A woman holding her cheek
However, Holmstrup’s group measured the effect of periodontitis on diabetes in rats.
His group studied the difference in blood sugar response in diabetic rats with a periodontitis-like condition and in diabetic rats without periodontitis.
Periodontitis caused a 30% increase in blood sugar following a meal.
The effects of tooth loss on health
The ultimate conclusion of periodontitis, if aggressive and untreated, is tooth loss.
Along with decades of chronic inflammation, tooth loss brings a whole new set of health risks, including cognitive decline and dementia.
Bei Wu, dean professor of global health at New York University’s Rory Meyers School of Nursing, found a quantity-dependent relationship: the more teeth lost, the greater the risk of cognitive decline and dementia is important.
In the largest study of its kind, Wu studied health data from 34,000 patients in the United States and found that for each tooth lost, the risk of cognitive decline and dementia increased by 1.4% and 1. .1% respectively.
Overall, people who had lost their teeth had a 48% increased risk of cognitive decline and 28% increased risk of dementia, compared to similar people who had all their teeth.
Tooth loss has been widely overlooked as a risk factor for dementia, and Ms Wu says she is usually looked at in surprise when she points out the link between the two.
“Oral health is a missing piece,” says Wu. “We’re trying to provide the evidence to show that it should be part of the equation.”
While periodontitis is a common cause of tooth loss, there may be other culprits for these effects than inflammation.
So far, Wu’s studies of tooth loss have only looked at correlations and not causation, but she wants to investigate the role of nutrition in this relationship, among other factors.
“Good teeth might improve nutritional intake and also your chewing,” says Wu.
“It might potentially increase blood flow, which might impact cognitive function, but that’s still just a hypothesis.”
Oral hygiene
The emerging links between our oral health and this series of other conditions have a very important result: it is easy to reduce the risk of contracting periodontitis and to treat it effectively if you already have it.
“If we brush our teeth properly and have good oral hygiene, we can potentially prevent the onset of periodontitis,” says Wu.
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Tooth loss is linked to many health problems
If the disease does appear, it can be treated at an early stage with scaling and root planing, which involves scraping microbes from the bottom surface of the tooth, above and just below the gumline.
If you have severe periodontitis, the solution may include surgical treatment, “which involves loosening the soft gum tissue, cleaning the root surfaces, and reattaching the tissue,” says Holmstrup.
The problem is detection, due to the often asymptomatic nature of the disease, coupled with the common misconception that unless you have a severe toothache, there is no need to go to the dentist .
Again, the solution is simple: if you have an appointment, don’t postpone it.
