Periodontal disease is an infection of the tissues that support the teeth.Teeth are supported by the gums, or gingiva. A tooth’s root is anchored to its socket by fibers called periodontal ligaments. The gums do not attach to the teeth as firmly as one might think. A shallow, V-shaped gap called a sulcus exists between the teeth and the gums. Periodontal disease affects this gap. Eventually, in periodontal disease, the tissues supporting the tooth break down. If only the gums are involved in this breakdown, the disease is called gingivitis. If only the connecting tissues and bone are involved, it is called periodontitis.