1. Department of Orthodontics, Institute of Oral Health Science, Ajou University School of Medicine, Suwon, Korea.
2. Department of Epidemiology, School of Public Health, Seoul National University, Seoul, Korea.
3. Department of Family Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
4. Department of Orthodontics, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Korea.