Popping a piece of sugar-free gum after a meal produces saliva, which helps wash enamel-eroding acid and cavity-promoting sugar off your teeth. Try gum sweetened with xylitol, a natural sugar alcohol that tastes sweet, but doesn’t give the damaging bacteria in your mouth any fuel for their dirty work. But don’t chew too much—xylitol in excess can, unfortunately, have a laxative effect.