Perioontitis (perio = around, dont = tooth, -itis = inflammation) refers to a number of inflammatory diseases affecting the tissues that surround and support the teeth. Periodontitis involves progressive loss of the alveolar bone around the teeth and may eventually lead to the loosening and subsequent loss of teeth if left untreated. Periodontitis is caused by a convergence of bacteria that adhere to and grow on the tooth's surfaces, along with an overly aggressive immune system response against these bacteria. Periodontitis is very common and in the USA has a prevalence of 30-50% of the population, but only about 10% have severe forms. A diagnosis of periodontitis is established by inspecting the soft gum tissues around the teeth with a probe and radiographs by visual analysis to determine the amount of bone loss around the teeth. Specialists in the treatment of periodontal diseases are known as periodontists and in the USA periodontics is an American Dental Association-recognized specialty.