1. Department of Orthodontics, The Catholic University of Korea, Seoul, Republic of Korea
2. Department of Dentistry, National Medical Center of Korea, 245 Euljiro, Junggu, Seoul 100-799, Republic of Korea
3. Department of Pediatrics, School of Medicine, Chosun University, 30-1 Hakdong, Donggu, Gwangju 501-717, Republic of Korea
4. Department of Prosthodontics, School of Dentistry, Kyung Hee University, Hoegidong, Dongdaemungu, Seoul 130-701, Republic of Korea
5. Department of Dentistry, Korea University, 80 Gurodong, Gurogu, Seoul 152-703, Republic of Korea
6. Division of Orthodontics, School of Dentistry, University of California San Francisco, 707 Parnasus Avenue, San Francisco, CA 94143, USA