Oral bacteria feast on sugar, which is why dentists always say to cut back on candy. But Layliev says sugar-packed foods that are also chewy, sticky, or crunchy – think granola bars, cake frosting, barbecue sauce, and dried fruit – are especially gum-ravaging. Besides being chock-full of sugar, these foods cling to teeth and gums and work their way into tiny crevices and pockets in your mouth.

Obviously, you're going to eat this stuff once in a while – just limit the frequency. "It's better to eat a piece of cake in one sitting than to snack on sticky, sugary foods throughout the day," Newhouse says. "The more times you expose your gums and teeth to sugar, the more chances the bacteria have to grow, and the greater your risk of periodontal disease." For this reason, Newhouse says that sipping on sugary beverages and juices, and even sugar-sweetened coffee, throughout the day is terrible for gums and teeth.