Flossing reduces the number of bacteria in your mouth. There are millions of these microscopic creatures feeding on food particles left on your teeth. These bacteria live in plaque which can be removed by flossing. Brushing your teeth only gets rid of some of the bacteria in your mouth. Flossing gets rid of the bacteria the toothbrush isn’t able to get to. That's the bacteria hiding in the tiny spaces between your teeth. If you do not floss, you allow plaque to remain between your teeth, and eventually it will harden into calculus/tartar therefore inducing periodontal disease. Plaque can be removed by brushing. Only the dentist or dental hygienist can remove calculus/tartar. Ask your dental professional to show you the proper way to floss. You will both notice the difference at the next cleaning appointment.