Social hermits and people who are constantly angry have an increased risk of gum disease.Believe it or not, that’s what a Harvard University study in the December issue of the Journal of the American Dental Association found.The study of 523 male health professionals found men who are angry on a daily basis had a 43 percent greater risk of developing periodontitis than those who were seldomly angry. It also found men who have at least one close friend had a 30 percent lower risk of developing gum disease than men who did not have a close friend.