Antibiotic premedication in dental treatment

By Dr. Randall Lawson

Preventive antibiotic treatment has long been used in dental treatment and is still considered an important part of dental care for certain groups of patients. It is very important that, if you are instructed to take pre-treatment antibiotics, you take them as instructed. My staff and I are often surprised at the misunderstanding that many people have of the importance of preventive antibiotics.

Over the years, dentists have used antibiotics prior to treatment for various purposes. Initially we used pre-treatment antibiotics-particularly penicillin- for the protection of heart valves which had been damaged by rheumatic fever. Rheumatic fever is caused by the same bacteria that can cause strep throat or scarlet fever. Rheumatic fever can progress to rheumatic heart disease which is infection of the heart valves with scarring of the valves. These scarred valves become stiffer and less able to form the seal necessary for the heart to work efficiently. Once this scarring occurs, the valves also become more susceptible to reinfection . Every time we perform any dental procedure that causes bleeding, bacteria are allowed into the blood system where they can then cause further infections of the heart valves. Each time this reinfection occurs (called Subacute Bacterial Endocarditis or SBE) the valves become less and less effective at pumping your blood through your body and nourishing it. Originally antibiotics were administered for a few days prior to dental visits and continued for a few days following treatment. This preventive treatment keeps bacteria from causing further damage to the valves. As research into the effect of this preventive treatment continued, it was found that shorter regimens of antibiotics were as effective as longer courses and we cut back to one dose before and one dose following dental appointments where bleeding might occur. Eventually the regimen went to one dose of 2 grams of Amoxacillin before an appointment. Finally, in 2007, The American Heart Association and other groups determined that administering only one dose of antibiotic is more likely to lead to the development of antibiotic- resistant strains of bacteria while offering only minimal protection from SBE. With these findings, as well as a large decrease in rheumatic fever occurrence, antibiotic premedication for the prevention of SBE was discontinued except for those with other health issues (e.g. uncontrolled diabetes).

At about this same time antibiotics began to be recommended for dental patients who have had whole joint replacement surgeries (hip,knee,shoulder). These joint replacements have less blood flowing around them due to surgical scarring. Since the blood system is the most important part of the body’s defense system this decreased blood flow could make these joints more susceptible to infection. There is some controversy in regards to the effectiveness of antibiotic premedication for these patients and last year the American Dental Association recommended that the practice be discontinued entirely. Most orthopedic surgeons seem to agree but are reluctant, at this time, to discontinue preoperative antibiotics. Until a better consensus develops within the orthopedic surgery community we will most likely continue with it. The recommended premedication regimen for joint replacement patients is 2 grams of Keflex 1/2 to 1 hour prior to your appointment.

Interestingly, while premedication for joint replacement may eventually be discontinued, a recent study in the United Kingdom seems to show that the incidence of Subacute Bacterial Endocarditis has been increasing since we stopped premedicating for it. Might we return to routine preventive antibiotics for this condition? The one certainty regarding antibiotic premedication is that its guidelines will always be subject to change. Always remember that this important preventive treatment is for your protection-if you are unable to take your premedication or forgot it please disclose this to you dentist because the alternatives can be quite unpleasant. For further information please check out the website of the American Dental Association at or our website at Thanks for reading.

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