How many millimeters is considered periodontal bone loss?

4. The healthy measurement is 2-3 mm. Anything above that is considered abnormal.
10mm. Periodontal pockets of 10 mm or greater are usually treated surgically.
3 stages. 3 stages of bone loss. Incipient: less than 4mm of bone loss. Moderate: 4-6 mm of bone loss. Advance: greater than 6mm of bone loss. Note periodontitis is a disease with progression of bone loss, not just a level of bone loss. Thus comparison of the bone level should be made for the definitive diagnosis of the active lesion of periodontitis.