It's hard to be long in the tooth when you've got no teeth, because they've all fallen out. At least you don't have to remember to brush them – not because you don't have any teeth, but because you've lost your memory because your teeth have fallen out. And, anyway, you're more worried about the condition of your heart and your lungs; the risk of developing disease in your vital organs has increased, because your teeth have fallen out.
We all know to look after our teeth lest they become yellow and unhealthy and require painful trips to the dreaded dentist. But how many of us would take more care if we realised how much the state of our mouths can affect our overall health. "People think of the mouth as some kind of compartment that's independent from the rest of the body," says Ian Needleman, professor of restorative dentistry at the UCL Eastman Dental Institute in London. "But that doesn't really make a lot of sense."
A study published last month suggests there could be a link between low tooth count, and poor memory. Scientists at the University of Kentucky in America put people aged between 75 and 90 through a test in which they were asked to recall 10 words they had been presented with five minutes earlier. All the participants, who repeated the test over three consecutive years, were from similar educational backgrounds, but there was variation in their results. People with fewer teeth scored lower than those with more teeth in the first test – and their scores declined far quicker thereafter.
Dr Nigel Carter, head of the British Dental Health Foundation, which has called the University of Kentucky findings "breakthrough scientific research", says the memory tests "add to a growing list of evidence of the wide-ranging systemic links relating to poor oral health". Previous studies have linked bad teeth to Alzheimer's, heart disease, strokes, diabetes, lung disease and even miscarriage and premature birth.
In many cases, including the memory study, Carter says the precise nature of the links remains to be identified – but the association of oral and overall health is increasingly an area of concern among doctors as well as dentists. If our mouths are the entrances to our bodies, perhaps it's logical that we should keep the gates – our teeth – in good working order, but how do bad teeth lead to bad health? "Bacteria," says Needleman (yes, he's heard the jokes). And he doesn't mean the friendly ones. "The problem is dental plaque, the soft, white, sticky deposits that can build up around your teeth."
If left to accumulate, the 700 strains of bacteria that can exist in plaque can cause gum disease, or gingivitis, which affects an estimated 50-90 per cent of the adult population. Gums become swollen and red and can bleed during brushing. Left to get worse, gum disease can become periodontitis, where inflammation also affects the tissue between tooth and jaw. Avoid treating that and you could end up with acute necrotising ulcerative gingivitis, which is as awful as it sounds.
Once swelling starts in the mouth, it can quickly cause problems elsewhere, including the heart. "The mouth can increase inflammation throughout the body," Needleman says. "It can trigger the release of a large number of chemicals known as mediators, which are the same causes of the inflammation implicated in heart disease." A 2008 study by scientists at the University of Bristol found that, when bacteria in the mouth get into the bloodstream through the gums, it can combine with platelets in the blood to create blood clots. If these reach the heart, they can cause heart attacks in people who are otherwise fit and healthy.
Needleman identifies a second route for bacteria invading the body from their bunkers in the mouth. "Research by us and other groups clearly shows that, among patients in intensive-care units, poor oral health can lead to a very serious condition called ventilator- associated pneumonia," he says. "Dental plaque can cause the mouth to become a reservoir for pneumonia-causing organisms that can pass through the airways and the tubes of a ventilator. There is also evidence of a risk of more standard forms of pneumonia."
A study published last week by researchers at the University of Edinburgh appeared to confirm a suspected link between gum disease and diabetes. They found that chemical change caused by inflammation in the mouth can reduce the effectiveness of insulin, making it more difficult for people with type 2 diabetes to control their blood sugar levels.
But Paul Batchelor, a senior lecturer at University College London and a consultant in dental public health, advises caution when linking the health of our gums to life-threatening conditions. "People are now keeping their teeth longer, brushing them better, smoking less and yet, suddenly, all these links are being found," he says. "It doesn't add up. If you look at the socio-economic distribution of health problems, it's always the poor who come off worse. People who are more likely to suffer from diabetes or heart disease, for example, are also more likely to have poor oral health."
Whatever its broader effects, gum disease is not only easily preventable (see our guide, below) but usually easy to treat. The key, however, is to spot it early. "Too often, people don't realise they have it," Needleman says. "Typical early signs are bleeding gums, but they are often dismissed as trivial – people expect to have them now and then. Gum disease only becomes apparent to most patients at a later stage, when the teeth become loose or cause eating to become difficult." By this stage, treatment becomes more complicated. Needleman says: "In very severe cases, surgery is required to regenerate or rebuild some of the lost gum and bone attachment."
Brush up on oral hygiene
Needless to say, make regular trips to see your dentist or hygienist, who will schedule your next appointment according to your lifestyle and the condition of your teeth. Gaps between visits can range from three months to two years.
Professor Damien Walmsley, scientific adviser to the British Dental Association, says, "It's important to be thorough. Clean up and down as well as back and forth, and roll the brush to ensure you clean where the tooth meets the gum."
Electric toothbrush sales are rising but they are no replacement for diligent brushing. Walmsley says, "You still need to use a proper brushing technique. But, if using an electric brush motivates people to keep their mouths clean, then great."
Brushing won't remove the build-up of plaque between your teeth and under the gum line – only flossing will do that. If you find it tricky, floss sticks or holders can make it easier to reach into the mouth.