Periodontal disease is when the tooth's bone tissue starts to deteriorate. Periodontitis occurs when plaque byproducts destroy the tissues that anchor your teeth in the bone. The gums deteriorate and begin detaching themselves from the teeth forming gum pockets, which allows more plaque to collect below the gum line. This causes the roots of the teeth to become susceptible to decay. Sometimes the patient notices an increase in sensitivity to hot and cold and to touch.