ANTIBIOTIC PROPHYLAXIS IN DENTISTRY: A REVIEW AND PRACTICE RECOMMENDATIONS

Background. The American Heart Association, or AHA, and the American Dental Association recently changed their recommended protocols for antibiotic prophylaxis against bacterial endocarditis. A new recommendation also has been issued by the ADA and the American Academy of Orthopaedic Surgeons, or AAOS, against routine antibiotic prophylaxis in patients with prosthetic joint replacements. These changes reflect increasing scientific evidence and professional experience in opposition to widespread use of antibiotic prophylaxis in these specific situations and others faced in dentistry.

Results. There are relatively few situations in which antibiotic prophylaxis is indicated. Aside from the clearly defined instances of endocarditis and late prosthetic joint infections, there is no consensus among experts on the need for prophylaxis. There is wide variation in recommended protocols, but little scientific basis for the recommendations. The emerging trend seems to be to avoid the prophylactic use of antibiotics in conjunction with dental treatment unless there is a clear indication.

Conclusions. Aside from the specific situations described, there is little or no scientific basis for the use of antibiotic prophylaxis in dentistry. The risk of inappropriate use of antibiotics and widespread antibiotic resistance appear to be far more important than any possible perceived benefit.

Clinical Implications. Dentists are wise to use antibiotic prophylaxis in only those specific situations in which there is a valid scientific basis for it. Whenever possible, dentists should follow the standard protocols recommended by the ADA, AHA or AAOS.

There is often confusion and misinformation concerning the indications and scientific basis for the use of antibiotics in conjunction with dental procedures. In this review article, we highlight specific situations that warrant the use of antibiotic prophylaxis in the dental setting and briefly discuss the rationale behind current recommendations.

The empiric use of antibiotic prophylaxis for dental procedures, especially those that cause bleeding in the mouth, has become a reasonably well-established practice among dental professionals. However, many dentists are confused by the indications for, and the nature of, antibiotic prophylaxis. They often rely on recommendations from practitioners who quote anecdotal evidence or decide that, when in doubt, the wise and conservative course is to use antibiotic prophylaxis. Furthermore, dentists may consult with a patient’s physician and receive a recommendation for the use of antibiotics in widely varying protocols and combinations. This presents a dilemma for the dentist because he or she may feel obligated to use antibiotic prophylaxis in inappropriate or unnecessary scenarios.

There is a long-held belief in the theory of focal infection such that subclinical infectious foci in the oral region, particularly endodontically treated teeth, result in systemic illness or cause disease processes in distant locations.Although generally regarded as not having scientific merit, this concept often drives recommendations for the use of antibiotic prophylaxis. As a result, dentists and physicians tend to use antibiotics in situations in which there are no clear scientific bases.

The correlation between bacterial infection and endocarditis was described before the turn of the 20th century. It was not until the 1920s, however, that the causal relationship between bacteremia, surgical procedures and infective endocarditis, or IE, was proposed. Lewis and Granthypothesized that surgical procedures provided microorganisms with access to the systemic circulation, which ultimately would result in endocarditis. The specific pathophysiology of IE was not yet identified. Researchers subsequently showed that IE arises from the colonization of a preexisting lesion, usually composed of fibrin and platelets, which develops from the disruption of the endothelial lining via abnormal development, disease or presence of foreign bodies and turbulent blood flow.^2,4

Since the 1930s and 1940s, when studies indicated a significant correlation among dental procedures that cause bleeding, bacteremia and the development of IE, the use of antibiotics has been standard practice for patients identified as being at risk of developing endocarditis. This practice has expanded to include patients at risk of developing infections around prosthetic joints and those with depressed immune systems.In addition, many medical and dental practitioners use antibiotics in conjunction with surgical procedures for otherwise healthy patients in the belief that such therapy will reduce the incidence of perioperative infections.

Clinicians and researchers are increasingly concerned about the overuse of antibiotics and the resulting development of resistant strains of microorganisms.Although the use of prophylactic antibiotics in dentistry is not a major contributing factor to the problem of overuse, the current situation clearly requires judicious and prudent consideration before antibiotic therapy is administered. 

CLINICIAL SITUATIONS CONSIDERED FOR ANTIBIOTIC PROPHYLAXIS

Infective endocarditis. IE, also known as acute or subacute bacterial endocarditis, is defined as an exudative and proliferative inflammatory alteration of the endocardium; it is characterized by vegetations on the surface or within the endocardium that are caused by an infection with microorganisms. A heart valve is commonly involved and proliferation also may occur in the inner lining of the cardiac chambers.^8,9 It is well-recognized that IE arises from the colonization of a preexisting lesion, usually composed of fibrin and platelets, that develops from the disruption of the endothelial lining via abnormal development, disease or presence of foreign bodies and turbulent blood flow. This accumulation of fibrin, blood products and platelets, known as nonbacterial thrombotic endocarditis, or NBTE, adheres to the damaged endothelium. The endothelium is later colonized by bacteria, which, in turn, stimulates further platelet aggregation and the bacteria become incorporated into the vegetations of the lesion.

Congenital or acquired cardiac defects and abnormalities may predispose the heart to endothelial damage and formation of NBTE. Researchers have suggested that these conditions may alter the hemodynamics of the heart, causing turbulence, which, in some way, increases the exposure of predisposed cardiac endothelium to bacterial infection (usually streptococcal).

The current AHA recommendations for the prevention of IE are significantly changed in respect to patients with various cardiac conditions. In general, the trend has been to more specifically describe those conditions that pose significant risk for patients and to delineate low- or negligible-risk situations. As a result, antibiotic prophylaxis is now recommended for fewer conditions. These changes also reflect improvements in the understanding of these disease processes and changing attitudes toward the use of antibiotics. The most notable among these changes include reducing the oral dose of amoxicillin from 3 grams to 2 g, recommending that a follow-up dose of antibiotic be discontinued, and replacing erythromycin with other antibiotics as alternatives to the penicillins. Dajani and colleagues have reported that 2 g of amoxicillin provides several hours of antibiotic coverage. Table 1 shows the new recommendations for prophylactic coverage for certain dental procedures.

Patients with mitral valve prolapse, or MVP, may be at risk of developing tachycardia, syncope, congestive heart failure and endocarditis. The risk of infection, however, is variable and depends on age and severity of the MVP.The decision whether to administer antibiotic prophylaxis is based on the results of echocardiographic tests for regurgitation. The AHA recommmends that patients diagnosed as having MVP with regurgitation receive antibiotic prophylaxis before undergoing dental procedures, but patients with MVP alone (without regurgitation) do not require antibiotic coverage. The risk of developing IE remains greater in patients with prosthetic heart valves and/or a history of endocarditis than in patients with MVP.The current American Heart Association recommendations for the prevention of infective endocarditis are significantly changed in respect to patients with various cardiac conditions.Patients often indicate on a health history form the existence of a heart murmur at some time without having any further knowledge of the nature or extent of the cardiac defect. Because of concerns about the overuse of antibiotics, it is prudent for the dentist to ask for medical evaluation before continuing dental care, rather than to simply prescribe antibiotic prophylaxis when in doubt. Similarly, if a dentist is treating a patient with MVP, it may be reasonable to contact the patient’s physician to determine the specific cardiac anomaly before making a decision about antibiotic prophylaxis.

Patients with prosthetic joints. Prosthetic joint replacement is becoming increasingly common, especially in developed countries with an aging population.  Infections of the prosthetic joints may be classified as early- and late-onset.

Early prosthetic joint infection is presumed to occur after microbial contamination of the surgical site during placement of the prosthesis. Late prosthetic joint infection, or LPJI, typically occurs three or more months after surgery and may involve delayed infection from microorganisms introduced at the time of surgery or via hematogenous spread from a distant site, such as the mouth. With devastating morbidity and a mortality rate of 18 percent, orthopedic surgeons are justified in their concerns about LPJI. The incidence of LPJI associated with dental procedures is extemely low. In a review of 2,693 patient records, Jacobson and Matthews found only one instance (0.04 percent) of LPJI that could be even temporally related to dental treatment.

Routine antibiotic prophylaxis for all patients with prosthetic joints is very expensive ($480,000 to prevent one case of LPJI in 1990). Studies of relative risks show that the risk of death caused by anaphylaxis, especially from the penicillins, far outweighed the risks of developing LPJI. These factors have moved the current consensus toward discontinuing routine use of antibiotic prophylaxis. In their advisory statement, the AAOS and the ADA have recommended the use of prophylactic antibiotics only for patients with total joint replacements (not for patients with only pins, screws and/or plates) and compromised immune systems, Type 1 diabetes mellitus, recent (within two years) joint replacement, previous prosthetic joint infections, malnourishment or hemophilia.

Dentists still may be faced with the situation in which a physician has recommended antibiotic prophylaxis for a patient that the dentist feels is inappropriate. In such cases, the dentist may choose to consult with the patient’s physician in an attempt to alter that recommendation. In any case, the dental practitioner is responsible for assessing each patient’s situation and deciding whether antibiotic coverage would benefit the patient.

PREVENTION OF LOCAL INFECTION IN SURGICAL OR OPERATIVE SITES IN THE MOUTH

Surgical procedures in the mouth generally fall into the clean-contaminated category of surgical classification (that is, native organisms are present); this includes routine exodontics, third-molar surgery and orthognathic surgery.The incidence of infection after dentoalveolar surgery is very low; for third-molar surgery performed by oral and maxillofacial surgeons, the infection rate is approximately 1 percent. Unless the immune system is compromised, antibiotics are not indicated in these cases. For periodontal surgery in which the surgical site is often highly contaminated with microorganisms, antibiotics are usually indicated for most patients with compromised immune systems, for patients at risk of developing IE and for patients with prosthetic joints, especially in the presence of obvious periodontal infections.

The periodontal literature suggests that localized juvenile periodontitis and other forms of early-onset periodontitis may warrant antibiotic coverage, but there is little evidence to support this view. The American Academy of Periodontology recommends that patients with medical conditions that predispose them to periodontal disease also be considered for antibiotic coverage. The use of antibiotic prophylaxis during placement of dental implants is controversial. Preoperative antibiotics appear to decrease the rate of implant failure, but studies have emphasized the prevention of implant failure rather than prevention of the infection itself.

PREVENTION OF GENERALIZED SPREAD OF INFECTIONS IN PATIENTS WITH COMPROMISED IMMUNE SYSTEMS

Patients with compromised immune systems represent a special category for dentists. Because of their illness and/or the treatment rendered for their specific condition, these patients are at higher risk of developing bacteremias, which, in the absence of an adequate host immune system, may rapidly progress to an overwhelming septicemia.

Patients undergoing chemotherapy are particularly susceptible to systemic infections because their immunosuppressed state is caused by their medications. Not only are these patients at higher risk of developing an infection, but the spread and severity of the infection can potentially be rapid and life-threatening. For these patients, we do not recommend antibiotic coverage for routine dental procedures, but it should be considered for invasive procedures such as dental extractions, deep periodontal scaling and other procedures that cause significant bleeding and seeding of bacteria into the systemic circulation.

Patients with human immunodeficiency virus and AIDS, in the absence of bacterial infection, do not generally require antibiotic prophylaxis. However, a clinical judgment should be made when a bacteremia is likely to occur, such as in cases of extraction of teeth with abscesses. Practitioners should consider the use of antibiotics in these patients because of the higher risk of overwhelming systemic infection and an inability to defend against microbial insult because of a depressed immune system.

The final group in this category of patients with compromised immune systems is the population with diabetes. Diabetics, especially those who are insulin-dependent, have a higher rate of systemic disease and often exhibit some degree of leukocyte dysfunction, which may contribute to higher incidences of infection. Insulin-dependent diabetic patients, particularly those with poorly controlled disease, are vulnerable to infections. Therefore, antibiotic coverage for invasive dental procedures is recommended in patients with poorly controlled or uncontrolled diabetes, but is generally not required for those in whom the disease is well-controlled or for those who are not dependent on insulin therapy.

There is some ongoing debate among clinicians and authors over the use of antibiotic coverage for chronic intravenous drug abusers and for patients who have undergone splenectomy. The incidence of IE among chronic intravenous drug abusers is several times higher than that seen in the healthy population. Although there is no clear-cut evidence that antibiotics are effective in cases of native valve endocarditis, antibiotic coverage may be warranted until new evidence suggests otherwise. There is also no evidence that patients who have undergone splenectomy are at higher risk of developing infection from dental procedures than is the general population. These patients are, however, more susceptible to infections from encapsulated organisms such as Pneumococcus and Hemophilus type B species; physicians often recommend the use of antibiotic prophylaxis for invasive dental procedures in such cases.

DENTAL PROCEDURES AND ANTIBIOTIC PROPHYLAXIS

The link between dental procedures and IE remains a controversial subject. In 1984, Guntheroth reported a low incidence of bacteremia associated with dental procedures and suggested that meticulous oral hygiene was more important in the prevention of IE than any antibiotic regimen. In a population-based control study involving 273 patients with cardiac lesions, Strom and colleagues found that dental procedures were not a risk factor for IE, even in patients with valvular abnormalities. Furthermore, even when the recommended antibiotic regimen was administered, it was not 100 percent effective in preventing IE.

The evidence is now clear that not all dental procedures warrant the use of antibiotic prophylaxis. It is safe to perform dental procedures (such as restorative and prosthetic treatment) in which the potential for bleeding is minimal in at-risk patients without the use of antibiotic prophylaxis. Invasive treatment in which bacteremia is more likely to occur (such as periodontal scaling, periodontal surgery and dental extractions) warrant the use of antibiotic coverage in patients with specific conditions, such as prosthetic heart valves and a history of endocarditis.

SUMMARY

As a result of greater understanding of disease processes, an enhanced awareness of cost-effectiveness and risk-benefit correlations, and better communication between medical and dental practitioners, the guidelines for antibiotic prophylaxis have been significantly altered. Although the major impetus for this change was related to prevention of IE, situations involving prosthetic joints and patients with compromised immune systems also have been reconsidered. In addition, the specific nature of dental procedures and the risk of patients’ developing bacteremias from them have been reconsidered, and many common procedures have been excluded from the list of those that require prophylaxis. It is clear that the trend is toward covering fewer and more specific medical conditions for a limited number of invasive dental procedures. Although some situations are well-delineated, controversy and concern over others continue. Further investigation and research are needed to clarify these issues.