1. First Clinical Division; Peking University School and Hospital of Stomatology; Beijing China
2. Department of Orthodontics; University of the Pacific, Arthur A. Dugoni School of Dentistry; San Francisco CA USA
3. Department of Dental Practice; University of the Pacific, Arthur A. Dugoni School of Dentistry; San Francisco CA USA
4. Department of Orthodontics; Craniofacial Research Instrumentation Laboratory; University of the Pacific, Arthur A. Dugoni School of Dentistry; San Francisco CA USA
5. Department of Orthodontics; Peking University School and Hospital of Stomatology; Beijing China