| Affiliation: | 1. Associate professor, Oral Department, Inner Mongolia Medical University, Hohhot, China; postgraduate student, Department of Orthodontics, School of Dentistry, Kyungpook National University, Daegu, Korea;2. Chairman and professor, Department of Orthodontics, School of Dentistry, Kyungpook National University, Daegu, Korea;3. Dental student, Oral Department, Jitang College, Huabei Coal Medical University, Tangshan, China;4. Assistant professor, Department of Orthodontics, School of Dentistry, Kyungpook National University, Daegu, Korea |
