1. Department of Periodontology, Ewha Womans University Mokdong Hospital, Seoul, Korea.
2. Department of Periodontology and Prosthodontics, Graduate School of Clinical Dentistry, Ewha Womans University, Seoul, Korea.
3. Department of Orthodontics, College of Medicine, Ewha Womans University, Seoul, Korea.
4. Department of Periodontology, College of Medicine, Ewha Womans University, Seoul, Korea.