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When thinking of heart attack risks, the common risk factors that come to mind are cholesterol, high blood pressure, or family history. But new research suggests that something as ordinary as the bacteria inside the mouth might also play a surprising role. Scientists have found that bacteria usually living harmlessly in the oral cavity can sneak into artery plaques and silently contribute to deadly heart events.

What the study found inside the arteries

A large study carried out by researchers at Tampere University in Finland analysed artery plaques from more than 200 patients. These samples included people who had died suddenly and others who had undergone surgery to remove blockages from their arteries. The shocking discovery: almost half of these plaques contained DNA from oral bacteria, especially a group called viridans streptococci .

Why is this discovery significant

This bacterial presence wasn’t just random. The study showed that these oral bacteria were linked with more severe forms of atherosclerosis , the condition where fatty plaques build up inside arteries. Even more striking, they were strongly associated with deaths caused by coronary heart disease and heart attacks. This suggests that these mouth bacteria are not bystanders but could be active players in plaque rupture .



How the bacteria manage to hide

What makes these bacteria especially dangerous is the way they live. They form something called a biofilm, a slimy shield that allows them to stay hidden deep inside artery plaques. The body’s immune system, which normally attacks invaders, fails to detect them there. As a result, the bacteria can sit silently for years. When triggered by stress, infection, or other factors, they may spark inflammation that makes the plaque unstable and more likely to burst, leading to a heart attack.

A closer look at the immune response

Researchers also found that when bacteria from the biofilm finally broke loose into the ruptured parts of the artery wall, the immune system did recognise them. This recognition activated inflammatory pathways, particularly through something known as TLR2 signalling. That immune reaction, while meant to fight off infection, might actually worsen the damage by adding more heat to the already inflamed plaque.

What this means for heart health

The study does not claim that mouth bacteria alone cause heart attacks, but it shows they could be a hidden risk factor. Oral health and cardiovascular health are more connected than previously believed. Poor dental hygiene, untreated gum infections, or even silent bacterial colonies could play a role in the development of life-threatening heart conditions. More research is needed to uncover exactly how these bacteria travel and trigger inflammation.

Disclaimer: This article is for informational purposes only and is based on findings published in the Journal of the American Heart Association. It is not intended to replace professional medical advice, diagnosis, or treatment. For any concerns regarding oral health, heart health, or related conditions, consulting a qualified healthcare professional is strongly recommended.

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