If enterococci, staphylococci, streptococci or bacteria of the HACEK group manage to get into the body, in the worst case they lead to inflammation of the endocardium. For years, doctors and dentists have been disputing the role played by bacteria in the oral cavity. In this context, it is questionable whether dental restorations really make sense before scheduled operations.
Get away from the forceps
Kendra J. Grim and Mark M. Smith, Rochester, have closely examined the issue based on treatment data. During the study period from 2003 to 2013, 205 patients underwent dental procedures when cardiac surgery was imminent. Most of them had caries or abscesses. Dentists carried out 208 extractions – with an average time period of seven days prior to the cardiac procedure. Most were heart valve OPs, sometimes in combination with bypasses or an aortic plasty. For 16 patients serious complications already occurred with the seemingly harmless interventions in the oral region. These complications included cerebrovascular events, an acute coronary syndrome and renal failure. Six patients even died shortly after the dental treatment. For a further fourteen patients the planned cardiovascular interventions had to be postponed. For comparison purposes, Smith cites the current guidelines of the American College of Cardiology and the American Heart Association. Both societies have evaluated dental surgeries to be minor procedures with mortality or cardiovascular complication rates below one percent. With regard to their far more critical results, Grim and Smith set out a few explanations. They see the anaesthesia itself as a possible trigger for adverse events. There is also a massive increase in inflammatory factors after tooth extractions, write the researchers. Last but not least there’s the matter of the delay of urgent cardiovascular interventions due to dental treatments. On account of the retrospectively evaluated data, the authors are cautious with giving advice. They do however suggest that each patient be evaluated individually.
Dentist and cardiologist have a rethink
Yet there are other possible interpretations. In one commentary on the study, Michael Jonathan Unsworth-White, Plymouth, uses clearer words than do the authors. Poor oral hygiene increases the risk of endocarditis. The dentist’s prophylactic approaches should minimise risks here. With regard to preventive dental extractions Unsworth-White refers to “accepted knowledge” which leads to carrying out thousands of procedures worldwide. “Dr. Smith’s group is asking us to put this philosophy into question: a significant departure from current thinking. This is however not the only paradigm shift in the interaction between the dentist and cardiologist. In his commentary Unsworth-White makes reference to the prophylactic use of antibiotics in order to prevent endocarditis: “The American Heart Association and the National Institute for Health and Clinical Excellence in the UK have withdrawn their support for this practice because the hazards of unnecessary antibiotic treatment outweigh any other risks”, says the scientist. Regular brushing, flossing and even chewing gum might even displace bacteria better than some of these forms of treatment.
Lost in the fog of the evidence
The state of affairs is however not so entirely straightforward, reports Anne-Marie Glenny of the Cochrane Oral Health Group, Manchester. Together with colleagues, she has investigated whether high-risk patients benefit from antibiotic prophylaxis. “It is known that invasive dental procedures can trigger bacterial endocarditis”, writes Glenny. “However, it is not known what level or measure of bacteremia actually lead to endocarditis.”Researchers therefore referred back to the Cochrane Oral Health Group’s Trials Register, the Cochrane Central Register of Controlled Trials, to MEDLINE and to EMBASE. At the same time records at the U.S. National Institutes of Health Trials Register and in the metaRegister of Controlled Trials were evaluated. Due to the low incidence of bacterial endocarditis, they included cohort studies and case-control studies, including possible comparison groups. Randomised, controlled studies were not available. At least one case-control study was however able to be found. The content: physicians in the Netherlands reported of 24 patients at risk who developed endocarditis within 180 days after having oral surgical interventions – despite antibiotics. Case reports from cardiac outpatient departments served as controls. Significant effects of pharmacological prophylaxis were not able to be demonstrated. Glenny: “There is no evidence pointing to whether the antibiotic prophylaxis is effective or ineffective in patients with the risk of getting bacterial endocarditis via dental procedures”. It is not clear, she believes, whether any damage and costs of antibiotics outweighed positive effects. She calls therefore for doctors before making any decisions to discuss and weigh out the benefits and risks with patients.