Date:  June 9, 2008

Summary: Bacteria from the mouths of patients who brushed their teeth and those who underwent tooth removal invaded the bloodstreams of some. However, the percentage of those with bacteria in the bloodstream varied, from 23 percent of those who only brushed their teeth to 33 percent of those who had a tooth removed and took an antibiotic and 60 percent of those who had a tooth removed and received a placebo (an inactive medication used as a control in scientific studies) instead of an antibiotic. Given the fact that toothbrushing occurs more frequently than tooth removal, more study of the risks of this routine task is warranted.

Journal: Circulation

Journal citation: Circulation. 2008;117:3118-3125

Read the original article: http://circ.ahajournals.org/cgi/content/full/117/24/3118

Why it’s important:  Bacteria that can enter the bloodstream through the mouth can be a cause of heart disease.  Understanding what kinds of procedures or activities enhance the likelihood of bloodstream infection may give physicians and dentists a better clue as to how to preventive a serious infection of the heart muscle called endocarditis.

What’s already known: Current American Heart Association guidelines note that only a minuscule number of cases of infection of the heart muscle (infective endocarditis) might be prevented by giving patients antibiotics before they undergo dental procedures. They note that such treatment should be restricted to patients with specific heart problems that pose the greatest risk for a bad outcome from getting endocarditis. Most people who received such antibiotic treatment before the new guidelines no longer have to take them.

Only seven studies have examined the relationship between heart muscle infection and toothbrushing. Of these studies, five were done between 1954 and 1977 and two were published after enrollment began for this study. These studies have shown a wide range of infection rates – from 0 percent to 100 percent after having teeth pulled, and 0 to 57 percent after toothbrushing. Few of these previous studies agree on the rate of infection or on the usefulness of prescribing antibiotics for preventing bacteria from spreading to the heart. In the meantime, the authors say maintaining healthy teeth and gums is the best protection against infection of the heart muscle stemming from bacteria in the mouth.

How this study was done:  Researchers assigned patients who needed to have a tooth or teeth removed to one of three groups. Members of one group were asked to brush their teeth and have their blood measured for bacteria; members of a second group had their tooth removed immediately and were given an antibiotic called amoxicillin to prevent infection; and members of a third group also had their tooth removed immediately but received a placebo instead of the antibiotic. (The patients who received drugs did not know if they got the antibiotic or the placebo.)  Over the three-year study period, 290 patients took part in the study. Those in toothbrushing group brushed for two minutes without toothpaste their tooth was removed. Those who had their teeth removed immediately received either the amoxicillin or the placebo an hour before the procedure.  Researchers took blood from each of the study subjects at the beginning of the study before brushing or tooth extraction and 1.5, 5, 20, 40, and 60 minutes after brushing or tooth extraction. The bacteria in the blood was cultured and then the DNA of the bacteria was sequenced in order to determine the presence of the species of bacteria associated with heart disease.

What was found:  Overall, the researchers found that 32 percent of subjects in the toothbrushing group, 56 percent of subjects in the tooth removal plus amoxicillin group, and 80 percent of subjects in the tooth removal plus placebo group had bacteria in at least one of their blood samples. Overall, the rate was 23 percent for the brushing group, 33 percent for the removal plus antibiotic group and 60 percent for the removal plus placebo group. The highest levels of bacteria in the blood were found in the first five minutes after the procedure. However, the group that had a tooth removed and received only a placebo had significantly higher levels of bacteria in the blood for as long as 40 minutes after the procedure. Because the subjects all needed dental work, they could have higher amounts of bacteria in the mouth, which could affect the results of this study.   

The bottom line:  Even toothbrushing can allow harmful mouth bacteria to enter the bloodstream. While this study does not provide data that indicate the need to change current AHA guidelines for administering preventative antibiotics to people with the highest risk of a bad outcome from endocarditis who undergo dental procedures, future studies of the comparative risk for getting endocarditis from dental procedures versus routine daily events such as toothbrushing are needed. Maintaining the health of teeth and gums remains the best prevention for the general population.



This content is reviewed regularly. Last updated 08/04/08.