Those many links between mouth and brain

Those many links between mouth and brain

Authors: Sim Singhrao, Dementia Researcher, Colin Michie, Paediatrician

Keeping your teeth throughout life will help keep your brain heathy. Smiling actors, models and all those Marvel characters enjoy showing off their amazingly and perfectly aligned chompers. But let’s take a reality check. How many of us, as ordinary people, have such amazing teeth?

 

Even in California, home to those fictional superheroes, more than one in six individuals over 65 have no teeth. Over 60% of adults will suffer with caries: these rates are high too in the Caribbean and Latin America. Gum disease is frequent, as almost everyone suffers some degree of gum disease. So gum and tooth disease are common human disorders – hanging on to all our precious teeth could be challenging.

Millions of mouth microbes

We are never alone. Large numbers of diverse bacteria, viruses and some fungi live on tooth enamel, cheeks, gums and tongue, in thin coatings or film, invisible to the naked eye. These are usually health promoting microbial communities. Biofilms are controlled by a battery of antimicrobial compounds, including antibodies, in saliva. A wealth of immune cells in our mouth, throat and nose also keeps a “neighbourhood watch” over the safety of our gums and teeth. Immune protections require support, but they cannot always be robust: smoking, excessive alcohol, poor diets and diabetes weaken them.

Build-ups of plaque on teeth and around the gums attract specific nasty microbes (and minerals too) which can evade these defence systems. Without plaque control, microscopic critters multiply, eroding protective surfaces and gum lining cells. This allows them to enter below the gum line, creeping down the tissues that anchor the teeth. Infection there can progress to an abscess and weaken the bone of the jaw. Should tooth enamel infection penetrate to the dentine underneath, decay can spread to the root canal causing the tooth pulp tissues to die, together with agonising toothache. “Tooth worms” may have been superstitious explanations for those incredible painful sensations of root canals being tortured by dysbiosis.

Microbes are competitive and mobile. Particularly once the gums are damaged, they can move out of the mouth down the gut, or into blood vessels, effectively spreading through the body, steering the way many organs function. Gum disease in pregnancy, for instance, can affect the size of the baby and start off premature labour. It can contribute to heart diseases and pneumonia; it can make problems such as arthritis and blood pressure worse. Perhaps most troubling, because we do not often think about it, is how mouth microbes influence our brains – this can be a direct hit. One particularly troubling gum disease microbe, Porphyromonas gingivalis can spread from tooth plaque to the brain, where it can cause inflammatory and cell changes also seen in ageing and memory loss.

Why you need your teeth!

Does losing a tooth really matter? False ones might seem more appealing, or whiter! Keeping your own intact teeth is important for several “brain” reasons. Tooth nerves are linked to areas of the brain that control memory. Tooth loss and gum disease can work as triggers for the development of Alzheimer’s and vascular dementias. Our brains are deeply linked with what goes on in our jaws. So how do we prevent our gums and their legions of tiny biofilm residents taking us down roads we should avoid?

This is a critical question for us adults, for our children and the elderly for whom we care. It seems wiser to adopt a healthy lifestyle, from an early age. Making healthful choices will pay off slowly and steadily, over time. Dietary checks with reference to sugar are important. Candies, those delectable bakery delights, desserts, and sweet drinks all produce an acid soup in our mouths as bacteria digest them. This damages enamel and encourages plaque development. Reducing or replacing sugars, eating more vegetables along with limiting snacking will greatly aid your mouth to protect its precious biofilm communities.

Biofilms can be well controlled mechanically with toothbrushes and flossing. Brush your teeth for two minutes with fluoridated toothpaste at least twice a day! Sugar-free chewing gums can reduce oral bacteria and increase saliva flow. As daily rituals, they prevent tooth decay and gum disease. Seek advice from your dentist and keep up regular dental checks too. A healthy choice is to attend dental appointments, and not to worry about the cost. Although we are supposed to all have 32 teeth as adults, their exact number, shape and spacing will differ. Expertise is valuable in keeping our dentition plaque-free and strong. Retaining memory in our older age is a precious and a fragile gift.

As you chew over this script and rehearse your “friendly island” smile, remember your oral hygiene – you can invest in your bite and your future brain capacities.

Useful resources:

https://www.nhs.uk/conditions/gum-disease/

https://www.cdc.gov/oralhealth/publications/OHSR-2019-edentulism-tooth-retention.html