Not brushing your teeth can have devastating consequences

Study links gum disease to heart conditions, dementia and diabetes.

Emma Jones 3 minute read October 23, 2020
Brushing teeth

Don't neglect your dental health, experts warn. Getty

A new study by the University of Toronto may have identified part of the body’s own immune system as a possible link between gum disease and increased risk of cardiovascular disease, certain forms of dementia, and diabetes.

Gum disease has been linked with two to three times the risk of heart attack, stroke, or cardiovascular disease, according to Harvard Health. Likewise, gum disease has also been associated with a higher risk of developing Alzheimer’s and other related forms of dementia. Researchers had previously thought increased risk of certain diseases could be due to the body’s immune response to infection — this study has found one of the first keys to this puzzle.

The missing link is an increase in neutrophils, a type of white blood cell and part of the body’s immune system that responds to inflammation. The researchers found that the presence of gum disease also increases the presence of neutrophils not just in the gums, but in various places throughout the body. It is believed that these cells then respond to any other infection with an overabundance of force.

“It’s almost as if these white blood cells are in second gear when they should be in first,” Michael Glogauer, senior author of the study and dentist-in-chief at the University Health Network, told UofT News. “…The [neutrophils] are much more likely to release cytokines much more quickly, leading to negative outcomes.”

The immune response to gum disease

A previous study by the University of Toronto demonstrated that neutrophils are activated to fight bacteria present in the mouth. Enzymes released by the neutrophils kill the bacteria, but can also corrode the dentin already damaged by the bacteria, potentially increasing tooth decay.

“It’s like when you take a sledgehammer to hit a fly on the wall,” Professor Yoav Finer, lead author of the 2019 study and the George Zarb/Nobel Biocare chair in prosthodontics at the Faculty of Dentistry told UofT News at the time. “That’s what happens when neutrophils fight invaders.”

Could it be possible that the immune system takes the sledgehammer elsewhere too?

Searching for the missing link

To find the link between gum disease and other inflammation-linked illnesses, the team first looked at a mouse model of periodontis. They found that presence of bacteria in the mouth was also correlated with an increase in neutrophils in the blood, colon, and lining of the abdomen. There was also in an increase of neutrophils in the bone marrow, indicating that the body increased production of these cells in response to the gum disease.

The researchers then looked at how this connects to humans. In an experiment that would make your mother cringe, volunteers were asked to not brush or floss their teeth for three weeks to cause gum inflammation. Blood and saliva were collected periodically through this period, as well as for two weeks after respondents started brushing their teeth again. Presence of neutrophils increased in the non-brushing phase of the experiment and then began to dissipate once volunteers resumed their oral hygiene routines.

“We believe this is the mechanism by which oral hygiene can impact vulnerability to unrelated secondary health challenges,” lead author Noah Fine, a post-doctoral researcher at the Faculty of Dentistry, also told UofT News. “Neutrophil (immune) priming throughout the body can connect these seemingly distinct conditions.”

To encourage good dental hygiene, the Canadian government recommends individuals brush their teeth for at least two minutes twice a day and floss once a day.


