The popular belief that gum disease can lead to heart attacks and strokes is a myth, experts said today.
Scientists writing in a respected US journal insisted there was no evidence for a causal link between bad gums and heart and artery problems.
The false message distorted the facts and spread alarm among patients, it was claimed.
A panel of 13 US experts spelled out their views in a scientific statement published in the American Heart Association journal Circulation.
The scientists reviewed 500 journal articles looking at links between gum and cardiovascular disease.
They concluded that while people with gum disease may be at greater risk of heart or artery disease, the association is probably coincidental.
Both conditions shared common risk factors, such as smoking, age and diabetes, and both produced similar inflammation markers.
Lifestyle may also play a role, said the experts. People who did not look after their hearts may also be less inclined to care about their dental health.
The common factors could help explain why diseases of the blood vessels and mouth can occur in tandem.
Research has shown that people with gum disease are almost almost twice as likely to suffer from coronary artery disease as those without gum disease.
Professor Peter Lockhart, co-chair of the expert panel and chair of oral medicine at the Carolinas Medical Centre in Charlotte, New Carolina, said:
"There's a lot of confusion out there. The message sent out by some in healthcare professions that heart attack and stroke are directly linked to gum disease can distort the facts, alarm patients and perhaps shift the focus on prevention away from well-known risk factors for these diseases.
"Much of the literature is conflicting, but if there was a strong causative link, we would likely know that by now."
He added: "We already know that some people are less proactive about their cardiovascular health than others. Individuals who do not pay attention to the very powerful and well-proven risk factors, like smoking, diabetes or high blood pressure, may not pay close attention to their oral health either."
Only a large, long-term study could prove that dental disease caused heart disease, but there was no likelihood of such an investigation being conducted in the near future.
"It's most important to let patients know what we know now, and what we don't know," said Prof Lockhart.
The belief that infected gums can lead to system problems such as heart disease has been suggested by doctors for more than a century.
Mouth bacteria are known to enter the blood stream during dental procedures, and even while brushing teeth. A number of theories have been suggested to explain the association between gum and heart disease.
One is that mouth bacteria attach to fatty deposits in arteries and trigger blood clots. Another is that they are a source of inflammation, which leads to a thickening of artery walls.
But the experts writing in Circulation said statements that imply a cause and effect relationship between gum and heart and artery disease were "unwarranted" at this time.
