1. State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, P.R. China.
2. Oral Department, Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, Chengdu, P.R. China.
3. Department of Oral and Maxillofacial Surgery, West China College of Stomatology, Sichuan University, Chengdu, P.R. China.