Kristen Hare interviews Jeff Donn, a national writer with the Associated Press, whose story last week revealed there's no evidence that flossing your teeth actually works. Donn tells Hare that his story began with a tip from his son's orthodontist. That led to a deep dig into research archives and a Freedom of Information request: "When I started to look at research, I realized that it was a good tip — and definitely the best one I ever got from an orthodontist."
August 8, 2016
