The practice of giving antibiotics to prevent infective endocarditis in susceptible individuals undergoing invasive dental procedures has been called into question by the results of a new study showing that the risk of bacteremia over the long-term is higher with tooth brushing than with tooth extraction.
Endocarditis is an inflammation of the inner layer of the heart, the endocardium. It usually involves the heart valves (native or prosthetic valves). Other structures which may be involved include the interventricular septum, the chordae tendinae, the mural endocardium, or even on intracardiac devices.
Bacteremia is the presence of bacteria in the blood. The blood is normally a sterile environment, so the detection of bacteria in the blood (most commonly with blood cultures) is always abnormal.
The study, published online June 9, 2008 in Circulation, was conducted by a group led by dentist Peter Lockhart (Carolinas Medical Center, Charlotte, NC).
There has been a 50-plus-year focus on dental procedures being covered with antibiotic prophylaxis to prevent infective endocarditis [IE] in susceptible individuals, but we have shown unequivocally that tooth brushing itself results in bacteremia in a significant percentage of cases. When you factor in the number of times you brush your teeth per year, compared with the number of times you undergo an invasive dental procedure, then the risk of bacteremia from tooth brushing is far greater than from dental procedures. [Because] it is not feasible to use antibiotics to prevent bacteremia from tooth brushing, one must therefore also question the use of antibiotics for dental procedures.
He explained that although antibiotics do reduce bacteremia associated with invasive dental procedures, the consensus among most experts now is that such antibiotic prophylaxis in susceptible individuals does not prevent endocarditis enough to justify the downside of using such large quantities of antibiotics. He added that the new guidelines in the UK have recently eliminated antibiotics altogether for heart patients undergoing dental procedures, saying that such use is not cost effective and that the risk-benefit might not be in the right direction.
Don’t stop brushing
Lockhart said the unintentional message from this paper is that brushing teeth is bad, but actually the opposite is true. “We need to focus our efforts more toward better dental hygiene. If the teeth and gums are kept clean, with regular brushing, and the dentist fixes any problems, this will reduce bacteremia and the associated risk of endocarditis,” he said, adding that the intake of refined carbohydrate (particularly sucrose) should be kept to a minimum because this feeds the bacteria in the mouth.
In the current study, 290 subjects were randomized to one of three groups: tooth brushing, single-tooth extraction with amoxicillin prophylaxis, or single-tooth extraction with identical placebo. Blood was drawn for bacterial culturing and identification at 6 time points before, during, and after these interventions. The researchers identified 98 bacterial species, 32 of which are reported to cause endocarditis. The overall incidence of bacteremia at any of the 6 draws was 32% for brushing, 56% for extraction with amoxicillin, and 80% for extraction with placebo (p<0.0001).
Lockhart et al write: “Although brushing does not appear to have the same incidence, duration, nature, and therefore magnitude of bacteremia as a dental extraction, we found a substantial incidence of bacteremia of IE-causing species from this common daily oral-hygiene activity. In addition, the brushing group had a larger percentage of positive cultures at 60 minutes (9% vs 2%). This suggests that brushing poses a risk for bacteremia similar to that of a dental extraction, given professional guidelines that recommend tooth brushing at least twice per day. Therefore, there is the potential for bacteremia from tooth brushing alone to occur more than 200 times per year, compared with an average of fewer than 2 dental-office visits per year per person.”
They add that bacteria commonly gain entrance to the circulation during tooth brushing through ulcerated gingival tissue that surrounds the teeth. Although dental extractions are among the most likely of dental procedures to cause bacteremia, tooth brushing can disrupt a far larger surface area of gingival tissue.
Antibiotics not 100% effective
The authors point out that although amoxicillin has a significant impact on bacteremia from a dental extraction, a notable number of the extraction patients who received prophylaxis in this study nonetheless showed evidence of bacteremia; this lack of 100% efficacy alters the per-dose risk-benefit ratio, increasing the number needed to treat to avert a distant site infection.
They conclude: “The incidence, duration, nature, magnitude, and daily occurrence of bacteremia from tooth brushing and other routine daily events (eg, chewing food) calls into question the appropriateness of and emphasis on prophylaxis for periodic dental procedures. Given the unfeasible concept of advocating antibiotic coverage for tooth brushing, we suggest that a controlled clinical trial is indicated to resolve this longstanding issue. In the meantime, there should be a greater focus on avoidance of dental disease in patients at risk for distant-site infection in general and for IE in particular.”