Periodontal pocket measurement
Probing depth tells us how deep the space between the gum and the tooth is – from the edge of the gum to the bottom of the sulcus or periodontal pocket. It is measured in millimetres with a periodontal probe.
With healthy gums the values are usually around 1–3 mm. Greater depths can mean inflammation, swelling of the gum, loss of attachment and/or loss of the alveolar bone. Pocket depth alone is not always enough, though: with recession a pocket can be shallow even where the tooth has already lost much of its support. That is why recession is measured as well, and the clinical attachment loss – CAL – calculated. CAL is the better indicator of the loss of periodontal support over time.
To diagnose periodontal disease. Probing tells us whether we are looking at healthy tissue, gingivitis or periodontitis. In periodontitis, inflammation and the breakdown of the supporting tissues deepen the pockets.
To establish the extent and severity of the disease. Measurements at several sites around each tooth show which teeth and which surfaces are affected – the basis for staging the disease and planning treatment. Probing forms part of the full periodontal examination, alongside bleeding, recession, attachment loss, furcations and tooth mobility.
To find actively inflamed sites. Bleeding on probing is an important sign of inflammation; the presence of pus points to a more active infection.
To plan therapy. Shallow pockets are usually managed with improved hygiene and professional cleaning. Deep pockets may call for scaling and root planing, reassessment, sometimes surgical treatment or further diagnostics with X-rays.
To monitor the success of treatment. The measurements form the baseline. After therapy we compare whether the pockets have become shallower, whether there is less bleeding and whether the condition has stabilised – one of the principal ways of tracking whether periodontal disease is progressing or has been halted.
The key point: probing depth tells us far more than “how deep the gum is” – it helps us assess inflammation, the loss of tooth support, the prognosis and the need for treatment.