1. Biomaterials & Tissue Engineering Division; Dept. of Endodontics, Prosthodontics and Operative Dentistry; University of Maryland Dental School; Baltimore U.S.A.
2. Department of Orthodontics; School of Stomatology; Capital Medical University; Beijing China
3. State Key Laboratory of Oral Diseases; West China College of Stomatology; Sichuan University; Chengdu China
4. Department of Prosthodontics; School of Stomatology; Fourth Military Medical University; Xi'an China