Bad teeth and bleeding gums may cause more than social problems.

They can end up causing heart disease, according to researchers from the Royal College of Surgeons in Ireland.

Poor dental hygiene can let more than 700 types of bacteria found in our mouths into the bloodstream, they said.

"The mouth is probably the dirtiest place in the human body," said Dr. Steve Kerrigan. "When bacteria get into the bloodstream they encounter tiny fragments called platelets that clot blood when you get a cut. By sticking to the platelets, bacteria cause them to clot inside the blood vessel, partially blocking it. This prevents the blood flow back to the heart and we run the risk of suffering a heart attack."

Another doctor said the problem is severe because other things you do to protect your heart don't stop these kinds of problems.

"It doesn't matter how fit, slim or healthy you are; you're adding to your chances of getting heart disease by having bad teeth," said Howard Jenkinson from the University of Bristol.

Jenkinson has been working to determine which bacteria are most likely to cling to platelets, and how the platelets themselves can protect the invaders from the rest of the immune system.

The findings suggest why antibiotics do not always work in the treatment of infectious heart disease.

A report on the work was given to the Society for General Microbiology's autumn meeting.