Kahng says that candies and gum made with the sugar alternative xylitol often still contain citric acid, which can damage tooth enamel.
"Although these have reduced to no sugar, it can be argued that excessive gum chewing can result in faster wear of the enamel," Kahng said. "I've also found that most xylitol candies are formulated with citric acid, which technically makes the candy sugar-free but acidic. People assume they are home free when choosing sugar-free candies, but an acidic pH can be just as bad when it comes to damaging the enamel."