Prevention of Infectious Endocarditis During Dental Operations

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Infectious endocarditis can be prevented during dental operations with the use of antibiotics

The hypothesis is that bacteria enters the blood stream within the course of medical interventions (bacteremia) and can potentially evolve into infectious heart muscle inflammations in patients with risk factors.

It is assumed that prophylactic administration of antibiotics can effectively and efficiently prevent these diseases. However, this idea has never been researched in human beings within the framework of a prospective, randomized and placebo-controlled study. The assumption of effectiveness and efficiency is based on inconsistent expert opinions, data from animal experiments, case reports, and data from studies on partial aspects of the concept and from contradicting data from observational studies.

The scientific community advances the following views on this issue:

  • There is insufficient evidence regarding the effectiveness of the medicinal prophylaxis of endocarditis
  • The current prophylactic practice is questioned by the scientific community
  • The current conventional indication for medicinal prophylaxis of endocarditis should be carefully considered. In general, prophylaxis is now only recommended to patients in whose cases it is expected that endocarditis will take a severe course
  • The importance of oral hygiene for the prophylaxis of an infectious endocarditis is emphasized by the scientific community

Development of Infectious Endocarditis

The current ideas about the development of infectious endocarditis view the formation of thrombi on the inside of the blood vessels (on the endothelium due to, e.g., a turbulent flow in the area of constrictions or endothelial lesions) as the initial event. Injuries to the oral mucosa within the course of dental interventions or those resulting from respiratory, urogenital, or gastrointestinal tract interventions are followed by a brief flooding of bacteria into the bloodstream with pathogens typical of endocarditis.

Depending on various virulence factors, this then leads to the nidation of microorganisms and the subsequent colonization of thrombotic deposits. The continued adsorption of fibrin and thrombocytes leads to the development of vegetations that are colonized by microorganisms. For that reason, the microorganisms are often difficult to reach with medicinal therapy.

This short-term bacterial flooding (referred to as transient bacteremia) has been described in many studies. The frequencies observed in this condition are extremely variable and range from 10% to 100 %, even in cases of tooth extractions. In 7-68 % of cases, transitory bacteremia is also observed in the context of daily activities such as brushing the teeth, using dental floss, and chewing food.

Since different analytical techniques and different sample taking times may significantly influence results, the data presented must be taken with a grain of salt. Despite the diversity of the oral flora, the observed bacteremias are mostly caused by oral streptococci of the so-called Viridans group, and these are frequent agents of infectious endocarditis. The concentration of these pathogens in the observed bacteremias is low, both after dental extractions as well as after daily routine activities.

Since far more than 50 % of patients with infectious endocarditis have no corresponding risk procedure that can be found in their medical histories, it seems likely that predominantly transitory bacteremias – which are not connected to a specific intervention – are the cause for these diseases.

Does the administration of antibiotics as prophylaxis make sense at all?

There is contradictory data about the effectiveness of prophylaxis with different antibiotics for the prevention of transitory bacteremias after dental interventions in human beings. Some studies show a reduction of the duration, extent, or frequency of the bacteremias, while other studies do not.

While local prophylaxis with iodine seems to possibly decrease the frequency of bacteremias during dental extractions, the effectiveness of Chlorhexidin must be assessed critically. To date, the effectiveness of antibiotic prophylaxis for the prevention of infectious endocarditis after dental interventions in human beings has only been demonstrated in retrospective studies.

In prospective case control studies, prophylaxis involving medications were either ineffective or only minimally effective, even under the assumption of 100 % effectiveness of the prophylaxis. This was not viewed as effective because the number of patients that would have to be treated would not be in reasonable proportion to the number of cases of endocarditis that would be prevented by it.

The lifetime risk for infectious endocarditis in the normal population is very low, although it is significantly higher in patients with heart muscle diseases. Patients with:

  • Mitral valve prolapse without insufficiency
  • Mitral valve prolapse with accompanying insufficiency
  • Congenital heart defects
  • Rheumatic heart defects
  • Valve prostheses
  • valve replacement
  • After an endocarditis

have a higher risk of contracting infectious endocarditis than the normal population. The absolute risk of an infectious endocarditis resulting from a previous dental treatment is unknown. An exact determination is difficult to pinpoint: On the one hand, dental interventions are frequent in the general population, and on the other hand, the incubation period for infectious endocarditis is unknown.

Older studies suggest that the incubation period could be between seven and 14 days, since up to 85 % of these events (insofar as they occurred after a dental intervention) were observed during this period.

Bild mit verschiedenen Antibiotika und anderen Medikamentendigitalpress.at - Fotolia

Antibiotika und andere Medikamente

However, a correlation between bacteremia after a dental treatment and a subsequent endocarditis has never been proven. Accordingto estimates, the absolute risk of infectious endocarditis after dental treatments in the normal population is 1:14,000,000.

A cost/benefit relation of the current use of prophylaxis treatment shows that even assuming complete effectiveness of prophylaxis, based on the existing facts, the number of patients that would have to be treated in order to prevent a single case of endocarditis is very high. Cost/benefit analyses reach contradictory conclusions.

A positive cost/benefit relation is only computed for individual indications with defined substances, if at all. On the other hand, an increased number of deaths due to current prophylactic practices have been computed for certain configurations when taking possible undesired effects of medications into consideration, these being an incidence of deadly allergic reactions of 15-25 per 1,000,000 patients treated with penicillin.

Paradigm Shift in Prophylaxis of Infectious Endocarditis?

Only insufficient evidence exists regarding the effectiveness and efficiency of antibiotic prophylaxis of infectious endocarditis. The scientific community no longer recommends prophylaxis for all patients, as it previously did. Instead, prophylaxis is only administered in special cases, such as in patients with a severely increased risk of an infectious endocarditis.

Patients who could expect the greatest benefits are those who would probably be faced with severe or lethal infectious endocarditis without medicinal prophylaxis. These include:

  • Patients with an existing valve prosthesis endocarditis
  • Patients with endocarditis in the anamnesis
  • Patients with congenital heart defects
  • Patients with prosthetic material (e.g. artificial heart valves)
  • Patients who’ve had a heart transplantation and an existing disease of the heart valves

With regard to these types of patients, prophylaxis may possibly seem reasonable, but the effectiveness has not been sufficiently proven. In general, antibiotic prophylaxis should be administered 30-60 minutes prior to a procedure. It only appears to make sense to administer antibiotic prophylaxis up to two hours after the intervention in cases where a patient did not receive a prophylaxis prior to the intervention.

Role of Oral Hygiene?

In the context of the possible role of transitory bacteremia within the course of daily routine activities such as the brushing the teeth or chewing, it has to be assumed that a particular significance is attached to good oral hygiene and a solid tooth restoration for the prevention of infectious endocarditis.

The present evidence supports the assumption that regular oral hygiene at home and at the dentist lowers the frequency of bacteremias in conjunction with daily routine activities.

This post is also available in: German

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