Flossing can help you remove the bacteria in the tight spaces between your teeth and under the gum line. Break off about 18 inches (46 centimeters) of dental floss. Wind most of the floss around the middle finger on one hand, and the rest around the middle finger on the other hand. Grip the floss between your thumbs and forefingers. Guide the floss between your teeth using a rubbing motion. When the floss reaches your gum line, curve it against one tooth. Use the floss to rub the side of the tooth in an up-and-down motion. Unwind fresh floss for your next tooth.