Dentists diagnose periodontal disease using a combination of methods recommended by the American Dental Association. These may include:

• Dental history (including medical history). Evaluations of the type and duration of symptoms, other systemic conditions present (such as heart disease, diabetes or pregnancy), oral hygiene habits, prescription drug use and other factors.
  
  
• Full-mouth x-ray. An x-ray performed in the dental office that shows all of the teeth, gums and alveolar bones connected to the jaw. The film can show if, and how extensively, the underlying periodontal ligaments, alveolar bones and gum tissue have been damaged.
  
  
• Periodontal examination. Measures the depth of periodontal pockets formed between the gums and teeth (sulcus) with a periodontal probe, a thin measuring rod with a rounded tip and notches indicating millimeters. It is placed at six points around the tooth: three sites on the inner (tongue) side of the tooth and three positions on the outer (facing the cheek) side.
  
  The dentist inserts the tip of the probe into the pocket along the side of the tooth until it meets resistance. A depth of 1 to 3 millimeters is normal. Anything above that requires treatment; the higher the number, the deeper the pocket, the more severe the periodontal disease. The dentist typically focuses on areas where gums bleed when touched or probed with dental instruments, where there are loose or shaky teeth, or where the gum line has receded exposing the surface of the roots (cementum).
  
  
• Tooth mobility. Gently shaking the tooth. If there is movement, it could be an indication of bone or tissue loss.

Some dentists may perform a relatively quick screening procedure developed by the ADA for early detection of periodontal disease. Called the Periodontal Screening and Recording (PSR) system, the screening method is performed during a person’s twice yearly dental checkup. The dentist examines each tooth looking for deep pockets and bleeding. If problems are found, a more complete examination follows.