Abstract: Trauma, infection and other factors often result in varying degrees or shape of ?the bone defect of alveolar bone, ?which have effect on the patient's appearance and health. In order to reconstruct the morphology and function of the bone defects, bone grafting are ruquired. Autogenous bone graft is a "gold standard"in bone defect, and its advantages have been known to clinicians, but its source is limited, and could easily lead to "secondary trauma" of the body . A rich source of allogeneic bone to meet the different forms of bone defects etc., become the second choice , and being increasingly used in the spinal fusion of orthopedics and extraction site preservation of oral. This article will make a review of the preparation, biological basis of allogeneic bone and its application in extraction site preservation.

Key words: Allogeneic bone, Biological mechanism, Autologous bone, Bone transplantation, Extraction sitepreservation