Periodontal disease is caused by plaque, a sticky film that is always forming on your teeth. Plaque contains bacteria that produce harmful toxins. If teeth are not cleaned well, the toxins can irritate and inflame the gums. Inflamed gums can pull away from the teeth and form spaces called pockets. The pockets provide a home for more bacteria. If the infected pockets are not treated, the disease can get worse. The bone and other tissues that support teeth are damaged. Plaque can be removed if you brush your teeth twice a day and floss daily. If plaque stays on teeth, it can harden into a rough surface called tartar. Tartar can only be removed when teeth are cleaned at the dental office.