June 9 (HealthDay News) -- Taking good care of teeth and gums may be crucial in preventing heart valve infection, a U.S. study finds.

Researchers examined whether daily dental activities such as brushing were as likely as major dental procedures such as tooth extraction to cause infective endocarditis (IE), a dangerous infection of the lining of the heart or heart valve that can occur when bacteria enter the bloodstream.

In the study of 290 dental patients, researchers analyzed the amount of bacteria released into the bloodstream (bacteremia) during tooth brushing and tooth extraction, with and without antibiotics. Blood samples were taken from the patients before, during and after these activities, and analyzed for bacterial species associated with IE.

The researchers found the incidence of IE-related bacteremia from tooth brushing (23 percent) was closer to that of extraction than expected -- 33 percent for extraction with antibiotics and 60 percent for extraction without antibiotics.

"This suggests that bacteria get into the bloodstream hundreds of times a year, not only from tooth brushing, but also from other routine activities like chewing food," study author Peter Lockhart, chairman of the department of oral medicine at the Carolinas Medical Center in Charlotte, N.C., said in a prepared statement.

"While the likelihood of bacteremia is lower with brushing, these routine daily activities likely pose a greater risk for IE simply due to frequency: that is, bacteremia from brushing twice a day for 365 days a year versus once or twice a year for dental office visits involving teeth cleaning, or fillings or other procedures," Lockhart said.

"For people who are not at risk for infections such as IE, the short-term bacteremia is nothing to worry about," he noted.

"If you stop oral hygiene measures, the amount of disease in your mouth goes up considerably and progressively, and you'll have far worse oral disease. It's the gingival [gum] disease and dental caries [decay] that lead to chronic and acute infections such as abscesses. It's that sort of thing that puts you at risk for frequent bacteremia, and presumably endocarditis if you have a heart or other medical condition that puts you at risk."

The study was published in the June 9 issue of Circulation.

SOURCE: American Heart Association, news release, June 9, 2008