1. State Key Laboratory of Oral Disease, West China College of Stomatology, Sichuan University, Chengdu 610041, P.R. China;
2. Dept. of Stomatology, Ningxia Medical University Affiliated Hospital, Ningxia Province, YinChuan, P.R. China;
3. Bloomberg School of Public Health, Johns Hopkins University, 615 N. Wolfe St., Baltimore, MD, USA; and
4. Dept. of Cleft Lip and Palate Surgery, West China College of Stomatology, Sichuan University, No. 14, Section 3, Ren Min Nan Road, Chengdu 610041, P.R. China