1. Department of Prosthodontics, Seoul National University Gwanak Dental Hospital, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
2. Graduate School of Clinical Dentistry, Ewha Womans University, 911-1 Mok-dong, Yangcheon-gu, Seoul 07985, Republic of Korea
3. Department of Orthodontics, Ewha Womans University, 911-1 Mok-dong, Yangcheon-gu, Seoul 07985, Republic of Korea