Why is tooth mobility not used to assess risk?
Mobility is a symptom of the loss of supporting bone, excessive occlusal force, short root length, or a combination of these conditions. Of these three conditions, the loss of supporting bone from the bone crest is used. Other causes of tooth mobility include pupal lesions, trauma and orthodontics. Hence tooth mobility relates to many conditions other than periodontitis, which reduces its value as a factor to determine the risk for periodontitis.
