Dental floss is a special type of thread. It is used for cleaning spaces between teeth which cannot be reached by toothbrushes. It is important to floss before brushing teeth and to floss at least once a day. Tooth brushing will not clean food that is packed between teeth. This 'food packing' can lead to unhealthy teeth and gums. Bacteria grow in this 'packed food' between teeth. These bacteria cause the surface of teeth (enamel) to break down. Then the teeth and gums and sometimes even the jaw can become seriously diseased. 