Q. Since my knee-replacement surgery, my dentist has insisted that I take an antibiotic before she does any work on me. What’s the risk if I don’t?

A. Taking an antibiotic before dental work is necessary to help prevent infections in only a few types of patients, such as those with artificial heart valves and those with a previous history of bacterial endocarditis, a type of heart infection. That’s because bacteria can enter the bloodstream through wounds in the mouth during a procedure and find their way to vulnerable organs or joints. In the past, there were broader recommendations that covered more people, including those with implanted knee and hip joints.

But now the American Dental Association doesn’t recommend antibiotics before dental procedures for people who have had a joint replacement because it has found no association between the procedures and prosthetic joint infections. And Consumer Reports has long reported on the importance of stopping the widespread overuse of antibiotics. Not only can they cause diarrhea, stomach pain, and serious allergic reactions, but overuse can also increase a patient’s risk of developing Clostridium difficile and breed antibiotic-resistant bacteria, a major public-health concern.

For more on the overuse of antibiotics, read "The Rise of Superbugs" and watch our video below.

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Editor's Note: This article also appeared in the December 2015 issue of Consumer Reports magazine.