Periodontitis is the name of a collection of inflammatory diseases affecting the tissues that surround and support the teeth. The presence of periodontal disease has also been linked with heart disease. Periodontitis involves progressive loss of the bone around teeth which may lead to loosening and eventual loss of teeth if left untreated. Periodontitis is caused by bacteria that adhere to and grow on tooth surfaces (microbial plaque or biofilms), particularly in areas under the gum line. Periodontitis is very common in most populations but the severe forms of the disease are less common. Gum disease can be prevented by regular visits with a dental hygienist. Dentists diagnose periodontitis by inspecting the tissues around the teeth with a probe and by radiographs to detect bone loss around the teeth. Although the different forms of periodontitis are bacterial diseases, a variety of factors affect the severity of the disease. Important “risk factors” include smoking, poorly controlled diabetes, and inherited (genetic) susceptibility.