1. Department of Periodontology, Korea University Anam Hospital, Seoul, Republic of Korea
2. Division of Periodontology, Department of Dentistry, College of Medicine, Hanyang University, Seoul, Republic of Korea
3. Division of Oral and Maxillofacial Surgery, Department of Dentistry, College of Medicine, Hanyang University, Seoul, Republic of Korea
4. Department of Periodontics, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, USA