Free Gingival Margin
The free gingival margin is the area of gingival tissue that exists between the sulcular epithelium, which is the gum tissue that lines the crevice that embraces the tooth, and the mouth’s epithelium, which is the outer surface of the gum tissue. This free gingival margin appears on the coronal part of the gums, meaning the side of the gums that is adjacent to the crowns, or visible parts, of the teeth. This is also known as the crest of the marginal gingiva. The free gingiva is tucked against the surface of the teeth and held in place by gingival fibers but is otherwise moveable, such as when manipulated by a dental probe or a toothbrush. In some people, there is a visibly demarcated margin that appears as a shallow linear depression known as the free gingival groove.
The free gingival margin ranges in width from .5 to 2 mm and is shaped in a scalloped pattern that matches the shape of the cementoenamel junction of the teeth. The gingival margin is somewhat more translucent than the attached gingiva, though the two types of tissues are otherwise similar in their firmness and hue. The tissue of the free gingival margin is not attached to the surfaces of the underlying teeth and is stabilized only by the gingival fibers; there is no bone supporting the free gingival tissue.
When there is migration of the gingival margin away from the tooth, this is called gingival retraction or gingival recession. Usually, when it is performed intentionally, as in for surgical procedures, it is referred to as gingival retraction. Gingival retraction may be performed by electrical, mechanical, or chemical means. When it is spontaneous or non-intentional, movement of the gingival margin is referred to a gingival recession. Gingival recession often indicates underlying inflammation or pocket formation, which is characterized by infected spaced around the teeth and below the gumline. Both gingival retraction and gingival recession can expose the roots of the teeth and should be treated promptly, though one is intentional and the other is not.
The two most common mechanical ways to perform gingival retraction are gingival retraction paste and the gingival retraction cord. Gingival retraction paste causes the least amount of damage to the periodontium and successfully keeps the exposed area dry. First, a special tip is placed between the tooth and the surrounding gum, into the gingival sulcus, and then the gingival retraction paste is injected into the sulcus, where it is left to set for a few minutes. It is then removed, resulting in a clean, dry, and clearly visible margin for treatment. A gingival retraction cord is an instrument that dental professionals use to provide a clear view of a tooth that is being prepared for a restoration. The cord is inserted below the gumline into the gingival sulcus and then wrapped around the tooth that is being prepared. Gingival retraction cords are more effective than gingival pastes but may cause more damage to the surrounding periodontium. In patients with a hearty, healthy periodontium, therefore, gingival cords may be preferable, as there is less risk of damage to the periodontium.