Periodontitis is chronic and occurs when plaque by-products lead to the destruction of the tissues that anchor teeth in the bone. As the disease progresses, pockets form and allow more plaque to collect below the gum line. Tooth roots are exposed and may become at risk for decay and are sensitive to cold and touch.here is no way to accurately predict exactly how long periodontitis will last. Periodontitis is more severe form of gum disuse in which the tissues under the gum line become infected with bacteria, and the gums start pulling away from the teeth.