Image caption Dentists recommend brushing twice a day

Scientists say they have established one reason why gum disease may increase the risk of heart disease.

The link between gum and heart problems has long been recognised but it is unclear if poor oral health is simply a marker of a person's general wellbeing.

UK and Irish experts now say bacteria enter the bloodstream via sore gums and deposit a clot-forming protein.

The findings are being presented at a meeting of the Society for General Microbiology.

Earlier this year a Scottish study of more than 11,000 people found people who did not brush their teeth twice a day were at increased risk of heart disease.

It backed up previous findings suggesting a link, but researchers stressed the nature of the relationship still needed further analysis.

Protective platelets

Scientists from the University of Bristol working with the Royal College of Surgeons in Ireland now suggest it is the Streptococcus bacteria - responsible for causing tooth plaque and gum disease - which may be to blame.

Their work shows this bacteria, once let loose in the bloodstream, makes a protein known as PadA which forces platelets in the blood to stick together and clot.

Research such as this makes a welcome contribution to further understanding the nature of the relationship between gum disease and heart disease Prof Damian Walmsley, British Dental Association

"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," said Professor Howard Jenkinson, who led the research.

"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."

While maintaining good dental hygiene could minimise the risk, the team is also investigating how the platelet-activating function of the protein PadA can be blocked.

Professor Damian Walmsley, scientific adviser to the British Dental Association, said: "Research such as this makes a welcome contribution to further understanding the nature of the relationship between gum disease and heart disease.

"It also underlines the high importance of brushing twice a day with fluoride toothpaste, restricting your intake of sugary foods and drinks and visiting the dentist regularly in order to maintain good oral health."

The British Heart Foundation said that were other factors besides oral health which had a greater impact on heart health.

But their senior cardiac nurse Cathy Ross added that combining good oral health care "with a healthy diet, not smoking and taking part in plenty of physical activity will go a long way in helping you reduce your overall risk of heart disease".