Periodontology, or Periodontics, is the branch of dentistry which studies supporting structures of teeth, and diseases and conditions that affect them.

The, supporting tissues are known as the periodontium, which includes the gingiva (gums), alveolar bone, cementum, and the periodontal ligament. The word comes from the Greek words peri, meaning around, and odons, meaning tooth. Literally taken, it means study of that which is "around the tooth".

Periodontal diseases take on many different forms but are usually a result of a coalescence of bacterial plaque biofilm accumulation of the gingiva and teeth, combined with host immuno-inflammatory mechanisms and other risk factors which lead to destruction of the supporting bone around natural teeth. Untreated, these diseases lead to alveolar bone loss and tooth loss and, to date, continue to be the leading cause of tooth loss in adults.