1. Department of International and Community Oral Health, Tohoku University Graduate School of Dentistry , Miyagi , Japan
2. Division for Regional Community Development, Liaison Center for Innovative Dentistry, Graduate School of Dentistry, Tohoku University , Miyagi , Japan
3. Department of Health Promotion, National Institute of Public Health , Saitama , Japan
4. Department of Dental Sociology, Kanagawa Dental University , Kanagawa , Japan
5. Center for Preventive Medical Sciences, Chiba University , Chiba , Japan
6. Center for Gerontology and Social Science, National Center for Geriatrics and Gerontology , Aichi , Japan
7. Department of Oral Health Promotion, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University , Tokyo , Japan