Adding tea to your diet could pay off the next time you visit the dentist. It is not a substitute for flossing, but drinking black tea could be good for your teeth. Reseachers say drinking tea between meals reduces the harmful bacteria that form plaque and cause cavities. Similar results have been found with green tea, but, researchers focused on black tea because it's more common in western culture. There is a catch though, black tea might fight cavities, but, it can also stain your pearly whites.