1. College of Stomatology, Qingdao University, Qingdao, Shandong, P. R. China
2. Department of Oral and Maxillofacial Surgery, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, P. R. China
3. Department of Orthopaedic Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, P. R. China
4. Department of Radiology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, P. R. China