Bacteria in the bloodstream caused by someone failing to brush their teeth regularly could lead to a greater risk of heart attack, according to scientists.
Research from the University of Bristol shows that bad dental hygiene leads to bleeding gums which let in about 700 types of bacteria.
These go straight to the bloodstream and are now known to be "independent factors" in causing heart disease - no matter how fit and healthy the person is.
Professor Howard Jenkinson, working with the Royal College of Surgeons, made the discovery after examining how harmful bacteria interact with blood cells.
The findings are to be announced at the Society for General Microbiology in Trinity College, Dublin.
Professor Jenkinson said: "Cardiovascular disease is currently the biggest killer in the western world. Oral bacteria such as Streptococcus gordonii and Streptococcus sanguinis are common infecting agents, and we now recognise that bacterial infections are an independent risk factor for heart diseases.
"In other words 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."
The only treatment for heart disease is aggressive antibiotic therapy, but with the rise of drug-resistant bacteria time is running out for this option, he warned.