1. Department of Prosthodontics Peking University School and Hospital of Stomatology 22 Zhongguancun South Avenue Beijing 100081 China
2. National Center of Stomatology National Laboratory for Digital and Material Technology of Stomatology National Clinical Research Center for Oral Diseases Beijing Key Laboratory of Digital Stomatology Peking University School and Hospital of Stomatology Beijing 100081 China
3. The Central Laboratory Peking University School and Hospital of Stomatology 22 Zhongguancun South Avenue Beijing 100081 China