Tools · Periodontal charting
Periodontal charting drill
Clinical attachment level (CAL) tells you how much support has been lost. Add the recession to the probing depth when the gingival margin sits below the cementoenamel junction (CEJ). Subtract when the margin sits above the CEJ. A margin right at the CEJ means CAL equals the probing depth.
PD probing depth (mm)
GM gingival margin to CEJ: + = recession (below the CEJ), − = above the CEJ
CAL = PD + GM
Stage III vs IV depends on complexity factors (for example tooth loss, furcations, bite collapse), not CAL alone. Source: 2017 AAP/EFP classification (S11, S13). Learn more in staging and grading.