The most common cause of periodontal disease is the activity of bacteria harbored by plaque, the tartar that builds up on teeth and gums not properly cleaned by regular brushing, flossing, and regular dental care. Symptoms include chronic redness and sensitivity, bleeding gums, loss of gum tissue supporting the teeth and, in advanced cases, bone loss and damage to the fundamental tooth structure. In this way, the root surfaces can be made once again acceptable to the body, and the gum can reattach, at least to a degree. Periodontal surgery also makes it possible to graft bone into defects to repair some of the damage. After root preparation, the gum is closed back with sutures and a dressing is often placed to keep the area undisturbed, especially for the first week.