If you have a heart condition but your doctor or dentist neglects to give you an antibiotic prior to your next dental procedure, don't be alarmed. According to new guidelines published by the American Heart Association (AHA), few people with heart disease need to take this precaution.

The practice of taking antibiotics prior to dental procedures began decades ago to prevent infective endocarditis (IE), a rare but very serious heart infection that requires long-term treatment with antibiotics and, in severe instances, surgical valve replacement.

Getting your teeth cleaned or having a cavity filled causes small cuts in the gums that allow bacteria in the mouth to enter the bloodstream. It's very unlikely that these bacteria will cause IE. But because IE can lead to heart failure, arrhythmias, stroke, and death if untreated, antibiotics have been widely prescribed as a preventive measure prior to dental work for a broad group of people with heart conditions such as structural and valve-related heart defects that may make it easier for bacteria to get trapped in the heart's inner lining.

Why the change? Recently, the AHA convened a panel to review all IE studies published between 1950 and 2006. They concluded that only patients at high risk for serious complications from IE should continue taking preventive antibiotics -- a decision that amounts to a 90% reduction in the number of patients who will get prescriptions for antibiotics before going to the dentist.

A study published in the journal Heart looked at the death rates from endocarditis in France and estimated that even high-risk patients with artificial heart valves who do not take antibiotics prior to a dental procedure have only a one in 54,000 chance of getting IE. In fact, the risks of antibiotic use outweigh the benefits; people are more likely to have an allergic reaction to an antibiotic than to develop IE. Limiting unnecessary antibiotics will save patients money, reduce the number of medications they must take, cut the chances of allergic reactions, and help prevent antibiotic resistance. For most people, controlling the amount of bacteria in your mouth with good oral care -- brushing and flossing twice daily -- is the best way to prevent infection.

Who still needs antibiotics? The updated guidelines advise preventive antibiotics for high-risk patients only. This includes people with:

• previous episodes of infective endocarditis (IE)
• artificial heart valve replacements and repairs
• valve problems after a heart transplant
• congenital heart defects, both before and possibly after repair