1. General Dentistry and Clinical Education Unit, Niigata University Medical and Dental Hospital, 2-5274 Gakkocho-dori, Chuo-ku, Niigata 951-8514, Japan;
2. Department of Periodontology and Endodontology, Oral and Maxillofacial Dentistry, Division of Medico-Dental Dynamics and Reconstruction, Institute of Health Biosciences, University of Tokushima Graduate School, Japan;
3. Department of Periodontology, Division of Oral Biology and Disease Control, Osaka University Graduate School of Dentistry, Japan;
4. Department of Pathophysiology-Periodontal Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Japan;
5. Department of Periodontal Medicine, Division of Frontier Medical Science, Hiroshima University Graduate School of Biomedical Science, Japan;