Could a vaccine end bad breath? Halitosis is primarily caused by oral bacteria that release smelly chemicals when they break down food. The bacteria form plaque by binding together and coating themselves with a protective film. "The more plaque on your teeth and tongue, the stronger the smell," says Eric Huang, a professor of dermatology at the University of California, San Diego. He and his colleagues devised a way to disrupt plaque formation by blocking the protein that holds bacteria together. Mice treated with a nasally delivered form of this vaccine (which can also be injected) produced fewer malodorous sulfur compounds than an untreated group and had less gum inflammation. Human trials are needed, and it could be five to ten years before the therapy is available. For now, regular visits to the dentist are the best way to reduce plaque, Huang says.