As kids, we learn that brushing and flossing your teeth is essential if we want to avoid tooth decay and have healthy gums.
But could keeping our gums healthy also help to reduce your risk of having a heart attack?
The idea of a link between oral health and the heart has been around for a century. But it has only been in the last few decades that health professionals have taken this link seriously enough to recommend dental care as a way of reducing your risk of heart disease.
The early stage of gum disease is gingivitis, which can make your gums red, swollen and more prone to bleeding when you brush them. This occurs when you let dental plaque build up in the space where the gums meet the teeth.
When gingivitis goes untreated, it can become a far more severe form of gum disease — periodontitis, where bacteria collects in "pockets" that form between the tooth and the gums. This causes further inflammation, weakening the structures that connect the teeth to the gums. Over time, teeth can become loose and fall out.
The problem with gum disease is you might not know you've got it until it's in the late stages because it is not a particularly painful disease, said Ivan Darby, a professor of periodontics at the University of Melbourne.
"Then all of a sudden they get recurrent abscesses, teeth become loose, teeth move and that's usually when things are fairly advanced," he said.
What's that got to do with your heart?
There is a big overlap between the risk factors for gum disease and heart disease — including lifestyle factors, poor diet, smoking and heavy alcohol consumption.
But there is also an association between the two diseases — that is, if you have one, you are more likely to have the other.
"People who have gum disease are at about twice the risk of developing heart disease than people who don't have gum disease," said Associate Professor Michael Skilton, a cardiovascular health expert at the University of Sydney.
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"What we don't know clearly yet is whether that's a causal link … there is reason to believe it may be."
There are two mechanisms by which doctors think gum disease could cause heart disease.
First, when your gums are inflamed it is thought the inflammatory molecules that cause the redness and swelling can escape into other parts of your body. They can then agitate inflammation in your arteries, playing a role in the further development of fatty deposits lining artery walls.
The second mechanism, is that the bacteria that causes gum disease can enter the bloodstream whenever your gums bleed. That type of bacteria is thought to promote fatty plaques that can get into the arteries around your heart and help cause heart disease.
Professor Darby points out that while there is a link, the impact of gum disease on overall heart disease rates is probably small.
A huge range of factors can influence the development of heart disease, and while gum disease could be one of them, it would not be the main factor in the majority of people, he said.
Why don't we know for sure?
The reason experts cannot definitively say that gum disease causes heart disease is because it is very hard to establish what is called a causative link between the two diseases.
To do this would mean having to monitor two groups of people — one with and one without gum disease — and leave the gum disease group untreated to see if they had a greater rate of heart disease.
"You can't not treat somebody if they've got a disease," Professor Darby said. "It's one of those things that's going to be very hard to prove."
Preventing gum disease
While maintaining good oral hygiene will reduce your chances of getting gum disease, Professor Darby said, there are also genetic factors that play a role in your oral health.
"Some forms [of gum disease] do run in families. So if your mum and dad lost their teeth early and your brothers and sisters have got problems then you might also get it," Professor Darby said.
The best way to prevent gum disease is to stop the plaque getting underneath the gum first place.
You will reduce your chances of getting gum disease if you:
- brush your teeth twice a day for two minutes.
- use dental floss to clean in between your teeth.
- avoid smoking.
- pay special attention to oral hygiene if you're taking medications, as some increase your risk of gum disease.
- have regular dental check-ups, especially if you are pregnant or have diabetes as these conditions increase your risk of gum disease.
What about ingrown toenails and heart disease?
Neither Professor Darby and Dr Skilton had heard of a link between ingrown toenails and heart disease, and there does not appear to be any mention in published medical literature.
Dr Skilton said like gums, a toe can become inflamed when the nail is ingrown — but the surface area of inflammation would be much smaller.
"That's not to say it wouldn't potentially have a small effect, and on a population level, that there could be some sort of an association, but I don't know that it would generally change the advice with regards to the prevention of heart disease or the general treatment of ingrown toenails," he said.
With that said, variations on the typical toenail can be an indicator of a range of diseases and conditions — including malnutrition, diabetes and an overactive thyroid.
In one study, researchers even collected toenail clippings and analysed how much nicotine they contained. They found higher levels of nicotine in the nail clippings predicted coronary heart disease in the group studied.