Answer:
A sulcus (also known as a gingival sulcus) is a valley-like depression which connects the gingival papillae situated in the interproximal space between two teeth. It lies below, and conforms to the shape of, the interproximal contact. It is covered by non-keratinized epithelium. The sulcus is considered an important site for the initiation of chronic periodontitis. In health, the depth of the sulcus is usually less than 3mm and contains no bacterial deposits. In disease, the depth may increase, and bacterial deposits (plaque and calculus) accumulate in the sulcus, leading to inflammation and destruction of the supporting tissues of the teeth, which is known as periodontitis