1. School of Public Health; The University of Hong Kong; Pokfulam Hong Kong
2. Department of International and Community Oral Health; Tohoku University Graduate School of Dentistry; Sendai Miyagi Japan
3. Center for Preventive Medical Sciences; Chiba University; Chiba Japan
4. Center for Gerontology and Social Science; National Center for Geriatrics and Gerontology; Aichi Japan
5. Department of Social and Behavioral Sciences; Harvard T.H. Chan School of Public Health; Boston MA USA