Because the short part of gingiva existing above the height of the underlying Alveolar process of maxilla, known as the free gingiva, is not bound down to the periosteum that envelops the bone, it is moveable.

However, due to the presence of gingival fibers such as the dentogingival and circular fibers, the free gingiva remains pulled up against the surface of the tooth unless being pushed away by, for example, a periodontal probe or the bristles of a toothbrush.