1. Department of Oral and Maxillofacial Surgery, Seoul Asan Medical Center, College of Medicine, University of Ulsan, Ulsan, Korea.
2. Department of Oral and Maxillofacial Surgery, School of Dentistry, Seoul National University, Seoul, Korea.
3. Department of Oral and Maxillofacial Surgery, Samsung Medical Center, School of Medicine, Sungkyunkwan University, Seoul, Korea.