Periodontitis is a set of inflammatory diseases affecting the periodontium, i.e., the tissues that surround and support the teeth. Periodontitis involves progressive loss of the alveolar bone around the teeth, and if left untreated, can lead to the loosening and subsequent loss of teeth. Periodontitis is caused by microorganisms that adhere to and grow on the tooth's surfaces, along with an overly aggressive immune response against these microorganisms.

A diagnosis of periodontitis is established by inspecting the soft gum tissues around the teeth with a probe (i.e. a clinical exam) and by evaluating the patient's x-ray films (i.e. a radiographic exam), to determine the amount of bone loss around the teeth. Specialists in the treatment of periodontitis are periodontists; their field is known as "periodontology" or "periodontics".

While the information of periodontitis in the Swedish section of this website is being translated, please refer to this site for further information about periodontitis at this stage.