1. Department of Orthodontics, Seoul National University Bundang Hospital, Section of Dentistry, Seoul National University, Seongnam, Korea.
2. Department of Oral Medicine and Diagnosis, College of Dentistry and Research Institute of Oral Science, Gangneung-Wonju National University, Gangneung, Korea.
3. Department of Orthodontics, Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Korea.
4. Division of Orthodontics, School of Dentistry, University of Minnesota, Minneapolis, MN, USA.