1. Department of Periodontology, School of Dental Medicine Tsurumi University Yokohama Japan
2. Division of Periodontology, Department of Oral Interdisciplinary Medicine, School of Dentistry Kanagawa Dental University Yokosuka Japan
3. Division of Periodontology, Department of Oral Biological Science Niigata University Graduate School of Medical and Dental Sciences Niigata Japan
4. Department of Periodontology, Graduate School of Medical and Dental Sciences Tokyo Medical and Dental University Tokyo Japan
5. Bunkyo‐Dori Dental Clinic Chiba Japan
6. Seikeikai Group Seikeikai Hospital Yokohama Japan