The bacteria in your mouth are probably more excited to eat Halloween candy than your kids are. When the bacteria eat the sugar and leftover food in the mouth, a weak acid is produced. That acid is what can contribute to cavities. But don’t hang up your costume just yet. It’s OK to eat candy on Halloween as a splurge as long as you’re brushing twice a day and flossing once a day all year long. Plus, some candies are less harmful than others. To help you sort through the trick-or-treat bag loot, check out the American Dental Association Halloween survival guide.