Which is the Most Important Measurement: Probing Depth or Attachment Loss?
Why aren't probing depths enough to make periodontal therapy decisions? What are attachment levels? How can you measure them and use them to help your patients?
Periodontal pocket measurements are taken by inserting a periodontal probe, held parallel to the tooth, under the free gingival margin. After inserting, gently "walking" the probe’s tip along the bottom of the pocket accurately measures the level of attachment of the tooth’s periodontal apparatus. The measurements are recorded at four to six points on each tooth. Normal for dogs is 2-3 mm; cats ˝-1 mm.
The measurement is either made from the base of the sulcus, or pocket, to the free gingival margin (probing depth=PD); or from the cemento enamel junction to the base (CEJ referenced attachment loss=AL). The loss of attachment apparatus is determined by either the direct measurement from the CEJ to the base, or by subtracting from the total probing depth the distance from the gingival margin to the cement-enamel junction.
When the gingival margin coincides with the CEJ, the loss of attachment and the pocket depth are equal; when the gingival margin is located apical to the CEJ, the loss of attachment will be greater than the pocket depth, when the gingival margin is coronal to the CEJ the loss of attachment will be less than the pocket depth.
So what is the clinical significance between probing depths and attachment loss, and how does their difference affect treatment? Measurements contribute to other periodontal indices in therapy decisions. Some examples: