For years, both orthopedic surgeons and dentists recommended that people with artificial knees or hips get a shot of antibiotics before any dental procedures, including simple cleaning, that might make gums bleed. They worried that bacteria in the mouth could get into your bloodstream and reach the site of the implant. In 2015, the American Dental Association said it was no longer routinely needed. People with knee implants whose immune systems are weak or who may be prone to infections may still need antibiotics before a dental procedure.