1. Department of Periodontics, Seoul St Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
2. Department of Oral Microbiology and Immunology, College of Dentistry, Dankook University, Cheonan-si, Chungnam, Republic of Korea.
3. Department of Oral Microbiology and Immunology, School of Dentistry, Seoul National University, Seoul, Republic of Korea.