In anatomical terms, a potential space is a space that exists between two proximal areas that are normally pressed together. The gingival sulcus is an example of an area of potential space; in this case, the potential space is between a tooth and the surrounding gums. The gingival sulcus is a groove that is lined by tissue called the sulcular epithelium. The depth of the gingival sulcus is bordered apically, or near the root of the tooth, by gingival fibers, and coronally, or near the crown of the tooth, by the free gingival margin. The gingival sulcus varies in depth from person to person, but a healthy depth has been determined to be 3 mm or less, a depth which can easily be cleaned by toothbrushes and other widely available oral hygiene tools.
The epithelium of the gingival sulcus, called the sulcular epithelium, is the thin, protective outer layer of the gum tissue; the sulcus is the potential space between the surface of the tooth and the sulcular epithelium. The sulcular epithelium is continuous with the junctional epithelium and the gingival epithelium, all of which protect the gingival tissue of the periodontium.
Regular cleaning of the oral cavity, including brushing and flossing, keeps the bacterial biofilm called plaque at bay, though plaque develops at the gingival margin, where the gums meet the teeth, relatively quickly after brushing and flossing. Eventually, however, plaque can enter the gingival sulcus, introducing toxins into the permeable junctional epithelium where the enamel and the gum tissue are attached and causing inflammation. A mild amount of inflammation in this tissue is normal and is controlled by a fluid produced in the gingival sulcus that is intended to wash the sulcus and protect against further bacterial invasion.
In addition to its ability to produce this protective fluid, called gingival crevicular fluid, the gingival sulcus has other specific characteristics. The ecosystem within the gingival sulcus is unlike any other part of the mouth. When periodontal disease is present, the gingival sulcus, a comparatively anaerobic ecosystem, can become a periodontal pocket, which is a chronicall and abnormally deepened gingival sulcus. This can happen in spite of the increased production of gingival crevicular fluid, deep in the recesses of the gingival sulcus.
The depth of the gingival sulcus varies from person to person usually averaging about 2 mm. If the depth of the gingival sulcus is chronically deeper than 3 mm, which may result from periodontal disease or for other reasons, it may be impossible to effectively clean the entire depth of the sulcus with regular home oral hygiene. This can allow dental plaque to accumulate in the gingival sulcus, weakening the fibers of the periodontal ligament that attaches the gum tissue to the teeth. If the bacterial microbes in plaque are allowed to remain in the sulcus for a prolonged amount of time, they will gradually erode the delicate fibers that make up the periodontal ligament, which can lead to further deepening of the sulcus, recession of the gingival tissue, damage to the periodontium, and eventual tooth loss.