1. Clinical Faculty, Department of Orthodontics, School of Dentistry, Seoul National University, Seoul, Korea; and Clinical Faculty, Department of Orthodontics, Kyung Hee University School of Dentistry, Seoul, Korea.
2. Graduate Student, Department of Dentistry, Graduate School, Kyung Hee University, Seoul, Korea.
3. Assistant Professor, Department of Orthodontics, Kyung Hee University School of Dentistry, Seoul, Korea.