Flossing is a way to clean the teeth and floss is still new to most people in China, but in many countries it has been used for a long time. Floss can play a role in cleaning the surface of the teeth, picking out the role of embedded food, mostly made of nylon thread, silk thread, polyester thread or waxed cotton thread, generally using 30 to 75 firm and smooth thread. The fibers of the thread are loose and not twisted together so that the fibers can be flattened out when used and can easily pass through the area of close contact between the teeth. It is best to floss once a day, especially after dinner, with the floss knotted into a ring, or the ends of the line around the two middle fingers, the remaining 3-5 inches between the two fingers, with two thumbs to press the line into the gap, along one side of the tooth surface gently pumped, and then the other side. Repeat four or five times until the surface of the tooth is clean or the blockage is removed. Flossing is safer with little damage to the gums, but use gentle pressure to press into the bottom of the gingival sulcus to clean the gingival sulcus area, but not into the tissue below the bottom of the sulcus to prevent symptoms such as bleeding and pain in the gums.