Scientists have discovered how plaque-causing bacteria in the mouth can trigger potentially fatal blood clots.
While the link between oral bacteria and potential heart disease and strokes is long established, experts have now found how these microbes can cause blood clots.
The Streptococcus bacteria normally live in the areas of the mouth called biofilms, where they cause dental plaque and gum disease.
But when they enter the bloodstream, they release a protein that binds together platelets from the blood in a protective layer, or clot, around the bug.
Professor Howard Jenkinson, from the University of Bristol, said: "When the platelets clump together they completely encase the bacteria.
"This provides a protective cover not only from the immune system, but also from antibiotics that might be used to treat infection.
"Unfortunately, as well as helping out the bacteria, platelet clumping can cause small blood clots, growths on the heart valves, or inflammation of blood vessels that can block the blood supply to the heart and brain."
Prof Jenkinson added the microbes can "wreak havoc" if not kept in check by good dental hygiene such as regular brushing and flossing.
Speaking at the Society for General Microbiology's autumn meeting in Nottingham, he said: "Poor dental hygiene can lead to bleeding gums, providing bacteria with an escape route into the bloodstream, where they can initiate blood clots leading to heart disease.
"People need to be aware that as well as keeping a check on their diet, blood pressure, cholesterol and fitness levels, they also need to maintain good dental hygiene to minimise their risk of heart problems."