Difference between probing depth and CAL?

Difference between probing depth and CAL?

• A. Probing depth is the distance from the gingival margin to the base of the pocket; CAL is from the CEJ to the base of the pocket.
• B. Probing depth is from CEJ to base; CAL is from gingival margin to base.
• C. PD is from tooth crown to gingival margin; CAL is from CEJ to apex.
• D. PD and CAL are identical measurements.

Answer: (A)

Probing depth and clinical attachment level both describe how far the supporting tissues extend, but they start from different landmarks. Probing depth measures from the gingival margin down to the base of the pocket, giving you the pocket depth at that moment. Clinical attachment level measures from the cementoenamel junction (CEJ) down to the base of the pocket, showing the true position of the attachment relative to the tooth crown. This is why they align when the gingival margin sits exactly at the CEJ—PD and CAL are the same. If the gingival margin has receded apically, the CAL becomes larger than the PD by the amount of recession. If the gingival margin is coronal to the CEJ (gum overgrowth), the CAL becomes smaller than the PD by that amount. In short, PD relates to the margin, CAL relates to the tooth reference point (CEJ) and the base of the pocket.

Probing depth and clinical attachment level both describe how far the supporting tissues extend, but they start from different landmarks. Probing depth measures from the gingival margin down to the base of the pocket, giving you the pocket depth at that moment. Clinical attachment level measures from the cementoenamel junction (CEJ) down to the base of the pocket, showing the true position of the attachment relative to the tooth crown.

This is why they align when the gingival margin sits exactly at the CEJ—PD and CAL are the same. If the gingival margin has receded apically, the CAL becomes larger than the PD by the amount of recession. If the gingival margin is coronal to the CEJ (gum overgrowth), the CAL becomes smaller than the PD by that amount. In short, PD relates to the margin, CAL relates to the tooth reference point (CEJ) and the base of the pocket.