1. Private Practice in Periodontics and Implant Dentistry, Seoul 02771, Republic of Korea
2. Department of Prosthodontics, Division of Dentistry, College of Medicine, Hanyang University, Seoul 04763, Republic of Korea
3. Department of Dentistry, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea
4. Department of Periodontology, College of Dentistry, Kyung Hee University Dental Hospital, Kyung Hee University, Seoul 02447, Republic of Korea