By the time an American reaches the age of 50, they’ve lost an average of 12 teeth each. By age 65 and over, more than a quarter (27.27 percent) have lost all their teeth.

Teeth really matter, and not just for eating, because the latest research shows there’s a clear connection between tooth loss and diminishing brain function.

Fortunately, there’s a silver lining for those who’ve had some or all of their teeth pulled. If the missing teeth are replaced quickly, the likelihood of developing dementia can be substantially reduced.

Since the loss of a tooth wouldn’t appear to affect the brain directly, researchers have suggested various reasons for the tooth-brain connection, such as pathogenic bacteria from gum disease entering the brain.

But the theory that tops the list is the impact of tooth loss on the ability to chew. This is because chewing (mastication) stimulates blood flow to the brain, as we’ve written about previously in this newsletter. In addition, several brain regions, in particular the frontal cortex, are activated during the process of mastication, and this activation is linked to better cognition.

Good chewing ability also allows us to eat a wider range of foods containing essential brain-supporting nutrients.

Chewing Protects the Brain – With or Without Natural Teeth 

Studies confirm the importance of chewing as such – no natural teeth required – to your cognitive health.

For instance, among 557 Swedish people aged 77 and older, there was no difference in the risk of cognitive impairment between those with natural teeth and those with artificial or prosthetic teeth. However, the odds of impairment were much higher for those who had difficulty chewing.

The authors concluded that tooth loss did not necessarily lead to cognitive impairment if there were no masticatory difficulties. In fact, a Dutch study found that in older people with full dentures, memory problems became evident only when there were difficulties with jaw mobility, bite strength, and reduced ability to masticate.

All the same it’s a good idea to hang on to your natural teeth. In July, a research group led by New York University looked at all the best human studies examining the link between tooth loss and cognitive function. Their findings underscore the importance of maintaining good oral hygiene.

The More Teeth Lost the Greater the Cognitive Harm 

The researchers included 14 studies in their analysis involving 34,074 adults of which 4,689 had impaired cognitive function. They discovered that participants with more tooth loss had a 48 percent higher risk of developing cognitive impairment and a 28 percent higher risk of being diagnosed with dementia even after adjusting to consider other risk factors.

Those with missing teeth were 23.8 percent more likely to have cognitive impairment if they didn’t have dentures compared to 16.9 percent among those with dentures. Further analysis revealed that people wearing dentures did have a small additional risk of cognitive impairment, but this wasn’t considered significant. That’s good news for those who replace their missing teeth with an oral prosthetic device, however, there’s more.

Tooth Loss May “Predict” Cognitive Decline 

In additional analysis using a subset of eight studies, they found that each additional missing tooth increased the risk of cognitive decline by 1.4 percent and dementia by 1.1 percent.

Commenting on this finding, lead study author Xiang Qi said, “This ‘dose-response’ relationship between the number of missing teeth and risk of diminished cognitive function substantially strengthens the evidence linking tooth loss to cognitive impairment and provides some evidence that tooth loss may actually predict cognitive decline.”

The study concluded that tooth loss leads to cognitive impairment and dementia with the risk increasing with each tooth lost, but “timely prosthodontic treatment with dentures may reduce the progression of cognitive decline related to tooth loss.”

While this research doesn’t prove a causal link, it strongly suggests the brain will be harmed by losing teeth. Fortunately, there’s an easy solution. Today, false teeth or even implants are easy to obtain and can greatly mitigate any risks to the brain if people act to replace missing teeth as soon as they occur.

I do want to flag a possible problem with the studies we’ve discussed. Tooth loss is closely correlated with low income and low education status. And those two factors are also correlated with dementia: well-educated people, for example, have lower rates of dementia than the less educated. As far as we can tell, the authors of these studies did not take income and education into account, so it’s possible that at least some of the correlation we’ve discussed between missing teeth and dementia is actually due to the fact that both are caused – at least in part — by something else completely: poverty and lack of education.


  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7380285/
  2. https://www.nyu.edu/about/news-publications/news/2021/july/tooth-loss-cognitive-impairment.html 
  3. https://www.jamda.com/article/S1525-8610(21)00473-4/fulltext 

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