It’s not just gummy bears, but all gummy-style candies should be avoided like the plague because they ruin teeth says Lawrence Fung, DDS, a cosmetic dentist at Silicon Beach Dental and spokesperson for Hello “Naturally Friendly” Oral Care. “They are terrible for your teeth since they stick to all areas of the tooth and the longer the contact the sweets have with the teeth, the more acid gets produced by cavity-causing bacteria.” Check out all the other top causes of tooth decay.