Treating gum disease can improve blood vessel health, a study has found.
Around 40% of adults have gum disease
Gum disease - periodontitis- is a bacterial infection which affects 40% of adults across the world and which can lead to tooth loss.
US and UK scientists, writing in the New England Journal of Medicine, say the finding might help prevent heart attacks and stroke.
The British Heart Foundation said the research showed good dental care could have additional health benefits.
It was already known that inflammation, which is the body's natural response to infection or injury, is linked to the changes in the arteries which underlie strokes and heart attacks.
How the two are linked has not been established.
One possibility is that the bacteria disturbs the way blood vessels dilate directly, since some bacteria can enter the bloodstream. Another theory is that disease might trigger a low grade inflammatory response throughout the body.
The study, by experts from University College London (UCL) and the University of Connecticut looked at 120 middle-aged patients who had severe gum disease, but no heart problems.
They were either advised on how to treat their gum disease themselves at home, or given intensive dental treatment involving the removal of plaque and the removal of teeth that could not be saved.
The intensive treatment led to some short-term inflammation of blood vessels and arteries.
But after six months, those who received the more intensive treatment showed a marked improvement in their gum disease, and also significant improvements in their blood vessel function.
Professor John Deanfield, of the UCL Institute of Child Health who worked on the study, said: "This is the first time that a direct link has been made between treatment for gum disease and improved circulatory function, which is relevant to some of the UK's biggest killers: heart attack and stroke."
Dr Aroon Hingorani, of UCL's Division of Medicine, who also worked on the study, said: "Elevations in blood pressure and cholesterol, as well as smoking and diabetes, are recognised as the main risk factors for cardiovascular disease, and these can be effectively treated.
"Nevertheless, heart attacks and stroke remain a major cause of disability and death."
Professor Deanfield added: "This finding has potential implications for public health, but further studies are now required to determine whether the treatment of severe periodontitis could directly contribute to the prevention of disease of the arteries (atherosclerosis), stroke and heart attacks."
Professor Peter Weissberg, Medical Director of the British Heart Foundation said: "This important new study provides direct evidence linking an improvement in dental health with better blood vessel function.
"Longer term studies will help show if this also means reduced levels of heart disease for this group of patients.
"It may be that people who take care of their dental hygiene avoid more than just a toothache."