The col is valleylike depression in the portion of the interdental gingival that lies directly apical to the contact area, and disappear when the adjacent teeth are not in contact or if the gingival has receded.
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Col is absent if teeth are missing/recession is present.
Below the contact area, the interdental gingiva assumes a nonvisible concave shape between the facial and lingual gingival surfaces forming the gingival col.
The col varies in depth and width, depending on the expanse of the contacting tooth surfaces.Wider in posterior teeth, narrower in anterior teeth.
The marginal gingiva varies in width from 0.5 to 2.0 mm from the free gingival crest to the attached gingiva. The marginal gingiva follows the scalloped pattern established by the contour of the cementoenamel junction (CEJ) of the teeth.
However, the marginal gingiva lacks the presence of stippling, and the tissue is mobile or free from the underlying tooth surface, which can be demonstrated with a periodontal probe or blowing air into the gingival sulcus.
Check out a Glossary of Dental Health Terms from WebMD.