Periodontitis is when the tooth’s bone starts to deteriorate. periodontisits occurs when plaque byproducts destroy tissue that anchor your teeth in the bone. The gums deteriorate and begin detaching themselves from the teeth forming gum pockets. These pockets allow more plaque to collect and build up below the gumline. These pockets can make teeth more suseptible to root decay (cavitiy below the gumline). Sometimes patients may notice the tooth or teeth become more sensitive to hot and cold and to touch.