Many of these products are overly abrasive and can take away the outer layer of your tooth called the enamel,” said Aikaterini Papathanasiou. Credit: iStockphoto Charcoal seems to be the latest thing—for cleansing your face and purifying your insides—and even brushing your teeth. But before you start using a charcoal-based toothpaste, it’s best to realize that claims that...