The idea that brushing and flossing your teeth might increase your risk of developing dementia or having a heart attack might seem like nonsense – but the links between oral health and other conditions are being seriously studied by a number of research groups. Most of these studies are still in progress, but a surprisingly wide range of conditions have been linked to oral health issues.
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Firstly it's important to say that there is no firm evidence of poor dental health "causing" dementia, however there have been a number of studies around the connections between the two health issues.
It is well-established that poor oral health is noticeably more common among people suffering from Alzheimer's disease than it is among the general population – even correcting for age and economic factors.
Of course the biggest factor here is that the cognitive impairment affects people's ability to look after their teeth and to visit a dentist. In fact the British Dental Health Foundation has suggested that dentists could play an important role in spotting the onset of dementia, through unexpected changes in oral health in their patients.
It has been demonstrated that having diabetes can increase one's risk of suffering from severe gum disease (periodontitis), but there is also evidence to suggest that there may be a causal link in the other direction as well.
Having gum disease has been shown to increase people's levels of glycated haemoglobin (also known as HbA1c or glucose) – and high blood-sugar levels are a big feature of type 2 diabetes. The two conditions may have a symbiotic relationship, as high blood-sugar levels mean bacteria can breed more freely in the mouth, increasing the risk of gum disease and dental decay.
The main symptoms of gum disease are bleeding in the mouth when eating food or cleaning teeth, swollen or red gums, bad breath, shrinking gums, gaps between teeth, loose teeth and pus appearing around the gum line.
Heart disease and heart attacks
Scientists have observed a clear link between gum disease and heart disease, though they are yet to establish a causal link in either direction. Professor Sarah Jane George, of the University of Bristol, is studying whether the bacteria which cause gum disease might be linked to coronary heart disease and heart attacks.
The line of inquiry is to investigate whether oral bacteria activate a string of proteins called the Wnt signalling pathway in endothelial cells (which line the inside of our blood vessels), immune cells and blocked arteries. It may emerge that blocking this pathway could reduce atherosclerosis – the phenomenon that sees plaque building up in the arteries.
As with heart disease, there is also an established correlation between gum disease and stroke, particularly in men and even when the results are adjusted to account for other risk factors such as smoking and hypertension.
Also, as with heart disease, the significance of this relationship is not fully understood – but one theory is that inflammation plays a big role, with increased white blood cells leading to more C-reactive proteins – which are associated with increased risk of heart disease and stroke.
There is a very strong correlation between rheumatoid arthritis (RA) and gum disease, with a 2012 study finding that 65 per cent of RA sufferers also had gum disease – compared to 28 per cent of patients without the condition.
As with the previous issues, a causal link has not been firmly established. However it has been shown that the presence of P. gingivalis (one of the main bacteria associated with gum disease) can lead to earlier onset, faster progression and greater severity of RA, and this can include increased damage to bone and cartilage.
Another study showed that treatment of gum disease without surgery could improve RA symptoms – suggesting that the two conditions may have a common systemic cause. For more information, see the National Rheumatoid Arthritis Society website.