1. Dental Materials Science, Division of Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Pokfulam, Hong Kong SAR, P.R. China
2. Department of Biomaterials Science, Osaka University Graduate School of Dentistry, Osaka 565-0871, Japan
3. Zhujiang New Town Dental Clinic, Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou 510275, P.R. China