1. Department of Prosthodontics; Asan Medical Center, College of Medicine, University of Ulsan; Seoul Korea
2. Department of Advanced Periodontics; University of Southern California; Los Angeles CA USA
3. Department of Preventive Medicine & Public Health; College of Medicine, Yonsei University; Seoul Korea
4. Department of Oral and Maxillofacial Surgery; Asan Medical Center, College of Medicine, University of Ulsan; Seoul Korea