Those venti cups with extra pumps of the sweet stuff are your worst dental nightmare. “Constant exposure to the milk and sugar over the course of an hour or more make it difficult for the saliva to combat against the sugars and acids produced by the bacteria in our mouths,” Dr. Neman says. “Saliva is the great protector of our teeth, and with the constant sugar attacks from taking sips of sugary drinks, over time the salivary glands fail to keep up.” Yikes!