1. Department of Geriatric Dentistry Peking University Hospital of Stomatology Beijing P. R. China
2. National Engineering Laboratory for Digital and Material Technology of Stomatology NMPA Key Laboratory for Dental Materials Beijing Laboratory of Biomedical Materials Peking University Hospital of Stomatology Beijing P. R. China
3. Shanxi Medical University School and Hospital of Stomatology Taiyuan Shanxi P. R. China
4. Central Laboratory Peking University School and Hospital of Stomatology Beijing P. R. China