1. Department of Periodontology, Research Institute for Periodontal Regeneration, Yonsei University College of Dentistry, Seoul, Republic of Korea.
2. Department of Periodontology, School of Dentistry, Dental Research Institute, Seoul National University, Seoul, Republic of Korea.
3. Clinic of Reconstructive Dentistry, Center of Dental Medicine, University of Zurich, Zurich, Switzerland.