Chapter 150
Long Teeth
As you get older, you usually eat less—and less healthfully. Between 40 and 70, food intake drops by about a quarter because you have less appetite. Taste buds become fewer, and the first things you stop tasting are sweet and salty. That can lead to oversweetening or oversalting your meals. If, on top of that, you eat more processed foods because of bad teeth, it creates a vicious cycle, even though long-term studies provide no clear evidence that tooth loss actually leads to poorer nutritional status. However, tooth loss has been linked to premature death and dementia.
A systematic review with meta-analysis found that both periodontitis and tooth loss are predictors of a shortened lifespan. Not all studies accounted for confounding factors such as smoking, which can increase the risk of both dementia and premature death, but the studies that adjusted their data accordingly still found an association between missing teeth and premature death. Teeth could merely be an indicator of general health or of robust genes. People who reach 100 have better oral health than people of their generation who died more than 40 years ago, and the same is true of the children of these 100-year-olds compared with their peers. But there is a possible causal connection that makes periodontitis shorten life.
Periodontitis is a chronic bacterial inflammation that destroys the tooth-supporting structures—the gums and the underlying ligaments and bone. These bacterial pathogens can enter the bloodstream and trigger a systemic inflammatory burden. That would explain the association between missing teeth and increased heart attack risk, as well as between periodontitis and other signs of vascular inflammation, such as erectile dysfunction. (With a look in your mouth, your dentist knows more about you than you realize!) Does that also explain the association with dementia?
Teeth Save the Brain
Systematic reviews with meta-analyses found that tooth loss or periodontitis is associated with cognitive impairment and dementia. You might initially suspect reverse causality here—that dementia leads to poorer oral hygiene. But prospective studies that followed people over time found that tooth loss apparently predicts cognitive decline, and the more missing teeth, the higher the risk.
In see.nf/overdentures I describe a series of fascinating experiments. For example, researchers in a study subtitled “New Teeth for Sharper Thinking” found that replacing missing molars with crowns affected pupil size, suggesting that the sensation of loss when trying to clench your teeth impairs brain function. Anyone who thinks that’s crazy has to see this: Ten people with no teeth—nine of them cognitively impaired, six of them severely—received removable dentures for a month, which were later snapped onto titanium implants in the jaw. The regular dentures, which stayed in place with adhesive cream and natural suction, did not significantly change the wearers’ cognitive function, but the ones securely attached to the implants had a sensational effect. Presumably, the dentures transmitted the same pressure sensations during chewing to the jaw nerves as natural tooth roots. Nine of the ten participants entered the study cognitively impaired, but eight out of ten left the study cognitively healthy. That means that well-fitting, stable tooth replacement not only improves self-confidence, social connections, and quality of life, but also brain function. Even better, though, is keeping the teeth you have.
The Better Mouth Rinse
If cavities are a bacterial disease, why not just kill the hole-eating beasts with antibiotics? This has been tried many times. But side effects such as antibiotic resistance, vomiting, diarrhea, and tooth discoloration prevented their further use. There are antiseptic mouth rinses with chemicals like chlorhexidine, which is considered the “gold standard” against plaque, but as I show in see.nf/mouthwash, there is a cheaper, safer, better option: using green tea as a mouthwash, with or without amla.
Don’t Overdo the Sugar
Our ancestors, who got by without a toothbrush for more than 10 000 years, had virtually no cavities. Why? Because they also didn’t have candy bars yet. Today, rotten teeth are probably the most widespread disease of humankind, and as I show in see.nf/sugar, sugar is the sole cause.
If you followed the recommendation to get at most 3 percent of daily calories from added sugar, you couldn’t even give little kids a serving of any of the ten most popular types of breakfast cereal that are most aggressively marketed to children. Of course, soda would be out too. Just one can of soda contains two days’ worth of sugar.
Officially, the American Association of Pediatric Dentists (AAPD) took the position that frequent consumption of sugar-sweetened beverages contributes significantly to the development and progression of cavities—so that was the official position before it accepted a million-dollar donation from Coca-Cola. After that, it said: “The scientific evidence does not allow a definitive conclusion about what role soft drinks play …” The comment from the science-based consumer protection organization CSPI was: “What a difference a million dollars makes!”
If we really wanted to minimize cavities, the ideal goal would be to reduce added sugar to zero. That would indeed eliminate cavities, but as a Kellogg’s-funded scientist put it, “this ideal is impossible to achieve.” The “dictatorial use of ‘tooth-friendly’ foods” could promote an “unsatisfactory diet” that is “not acceptable to everyone.”
In response to calls for a “draconian” reduction in sugar, the sugar industry replied that people should “instead pay more attention to using fluoride toothpaste.” This is the perfect illustration of how medicine approaches self-inflicted diseases: Why address the causes when you can treat the consequences?
Are Dental X-rays Safe?
Each year, doctors are estimated to cause 29 000 cancer cases through X-ray radiation from CT scans. What about dentists? Dental X-rays are the most common non-natural exposure to high-energy radiation that tens of millions of Americans are subjected to each year. Don’t the lead apron and the neck shield (for the thyroid) protect the most important organs? Yes—every vital organ except one: the brain!
As I describe in see.nf/dentalxrays, dental X-rays apparently increase the risk of the most common brain tumor. There is little evidence that it helps to X-ray asymptomatic patients in search of hidden problems in the oral cavity. Therefore, dentists should take X-rays only when they expect the images to provide unique information that will affect the diagnosis or treatment of the patient in question.
Tooth-Preserving Nutrition
What role does diet play in periodontitis? In see.nf/periodontitis I go into the evidence, including intervention studies showing that vegetarians have better gum health, either because they eat fewer pro-inflammatory foods or because they eat more anti-inflammatory components such as fiber. As I describe in detail in see.nf/chewing, there was even a remarkable study in which more than 1000 participants were randomized practically from birth to decades of a healthy diet. Those who consumed less saturated fat and cholesterol ended up with better saliva flow, which is essential for oral health. It could be due to all the chewing required by fiber-rich foods. It was also found that foods that have to be chewed intensively combat bad breath.
The Bristly Path to Dental Health