the apical migration of the gingival crest. atrophy of the gingival margin associated with inflammation, apical migration (proliferation) of the epithelial attachment, and resorption of the alveolar crest.
1. a drawing or shrinking back; the laying back of tissues to expose a given part. 2. distal movement of teeth; a distal or retrusive position of the teeth, dental arch, or jaw.