1. State Key Laboratory of Organic–Inorganic Composites
2. Beijing Laboratory of Biomedical Materials
3. Beijing University of Chemical Technology
4. Beijing 100029
5. P. R. China
6. Department of Dental Materials & Dental Medical Devices Testing Center
7. Peking University School and Hospital of Stomatology
8. Beijing 100081
9. Department of Geriatric Dentistry