1 Department of Periodontics, College of Medicine, The Catholic University of Korea, Seoul, Korea.
2 Department of Dental Science and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea.
3 Yonsei Goodday Dental Clinic, Seoul, Korea.
4 Department of Periodontology, School of Dentistry, Kyungpook National University, Daegu, Korea.
5 JTS, Seoul, Korea.
6 Department of Periodontology, Periodontal-Implant Clinical Research Institute, College of Dentistry, Kyung Hee University, Seoul, Korea. ssyislet@khu.ac.kr.