1. Department of Oral and Maxillofacial Surgery, Wonju College of Medicine, Yonsei University, Wonju, Korea
2. Department of Oral and Maxillofacial Surgery, School of Dentistry, Gangneung-Wonju National University, Gangneung, Korea
3. Department of Pediatric Dentistry, School of Dentistry, Kyunghee University, Seoul, Korea