1 Department of Orthodontics, The Affiliated Hospital of Qingdao University, Haier road #59, Qingdao, 266000, Shandong, P.R. China.
2 School of Stomatology, Qingdao University, Qingdao, China.
3 Department of Stomatology, Qingdao Municipal Hospital, Qingdao, China.
4 Department of Orthodontics, The Affiliated Hospital of Qingdao University, Haier road #59, Qingdao, 266000, Shandong, P.R. China. yuanxiaoqd@qdu.edu.cn.
5 School of Stomatology, Qingdao University, Qingdao, China. yuanxiaoqd@qdu.edu.cn.