Kee-Joon Lee1, Young-Chel Park, Woo-Sang Hwang, Eui-Hyang Seong. 1. Department of Orthodontics, College of Dentistry and Oral Science Research Center, Institute of Craniofacial Deformity, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752, Korea. orthojn@yumc.yonsei.ac.kr