When an orthodontist asked the reporter if he wanted a good story idea, the reporter, of course, said "yes." Jeff Donn, a national writer with The Associated Press and 2012 Pulitzer finalist, was doubtful, at first, about that tip from his son's orthodontist: There's no solid evidence that flossing actually works. "But 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." As a reporter who's covered the dangers of aging nuclear power plants, drug safety and abandoned oil wells, Donn was attracted...