It might sound like a horror movie but the fact is, if you have certain species of pathogenic oral bacteria in your gums, they could be slowly making their way into your brain as you read this. These bacteria among 100s of others responsible for oral health issues, including tooth decay, cavities and periodontal disease (or gum disease).

The bacterial invaders identified so far

UK researchers have identified three bacterial species (see below) capable of entering the brain:

  • Porphyromonas gingivalis (left),
  • Treponema denticola (centre), and
  • Tannerella forsythia (right).

How do they get there?

First off, all of these bugs need to establish colonies in plaque and calculus. That’s easy for them if you fail to maintain a proper oral hygiene routine that includes brushing your teeth twice daily and visiting your dentist every 6 months.

Next, once firmly established in the periodontal tissues (below your gum line), they can infect surrounding soft tissue and bone. That’s when you start to develop periodontal pockets and gum disease. Along with these oral conditions, you may start experiencing symptoms such as bleeding gums – their first point of exit to the rest of the body.

All they have to do then is to wait until the next bleeding event – triggered by brushing your teeth or eating food – when they hitch a ride on your red blood cells along the blood stream super highway straight into your brain. And it’s a fairly easy entry for them since your brain lacks immune checkpoints.

The other way two of the mentioned bacteria can access your brain tissue is quite unique. Since they are motile (the ability to move), they can creep along the nerve fibres that connect your tooth roots to your brain.

What happens once they get there?

In short, they can settle in biofilms (similar to the plaque on your teeth) in the areas of your brain related to memory. When your immune system eventually cottons on to what is happening, it will respond and attack the bacteria.

Now that’s okay as a one off, but repeated daily exposure to these oral bacteria and their by-products, can result in neuron and nerve cell death in your brain according to UK researchers in a 2014 study. As such, the presence of oral bacteria in the brain and the associated side-effects has been linked to the development of Alzheimer’s disease.

Browns Plains Alzheimer’s disease

Stop them at the gates!

Once P. Gingivalis and company are in your system, it can be rather difficult to get them out completely. That’s why proper oral care and regular visits to a dental hygienist throughout your life are so important – to prevent these bugs from entering your body in the first place.



Poole, S., Singhrao, S. K., & Crean, S. J. (2014). Emerging evidence for associations between periodontitis and the development of Alzheimer’s disease. Faculty Dental Journal, 5(1), 38-42. doi:10.1308/204268514×13859766312719

Singhrao, S. K., Harding, A., Poole, S., Kesavalu, L., & Crean, S. (2015). Porphyromonas gingivalis Periodontal Infection and Its Putative Links with Alzheimer’s Disease. Mediators of inflammation, 2015, 137357.