There are untold legions of viruses, fungi and bacteria living in your mouth. It now seems we can stave off conditions from Alzheimer’s disease to cancer by keeping them in a healthy balance

It is always the same vibe: the glossy, out-of-date magazines, the smell of sterilising fluid, the inevitable fish tank. Dentists’ waiting rooms aren’t much fun, and when you go through to the surgery, it only gets worse. The chair tilts back with an electric whir, the masked face says “open wide” and out comes an array of sharp, metal implements. No wonder many of us emerge rubbing our gums and wondering how long we can put off our next appointment.

But perhaps we need to recalibrate our relationship with our oral health, because there is a consensus emerging that looking after it might be the underappreciated secret to a longer, healthier life.

What matters isn’t so much having pearly whites per se, but looking after our oral microbiome: the viruses, fungi and 700 or so species of bacterium that reside in our mouths. Let our oral hygiene slip, and bad bacteria from there can travel all over the body, causing or exacerbating problems, from cardiovascular disease and cancer to Alzheimer’s disease and arthritis. Keeping everything in balance, on the other hand, staves off decline.

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More recently, DNA sequencing technology has improved apace, enabling us to catalogue the microbes in our mouths. Thanks to this, we are now finding that the types of bacteria people have living there seem to be associated with a growing number of conditions. We know, for instance, that people with gum disease are as much as 20 per cent more likely to get cancer in their lifetimes compared with otherwise healthy people.