1. Department of Prosthodontics Peking University School and Hospital of Stomatology, National Clinical Research Center for Oral Diseases, National Engineering Laboratory for Digital and Material Technology of Stomatology, Beijing Key Laboratory of Digital Stomatology No.22 Zhongguancun South Avenue, Haidian District Beijing 100081 P.R. China
2. Department of Second Clinical Division Peking University School and Hospital of Stomatology, National Clinical Research Center for Oral Diseases, National Engineering Laboratory for Digital and Material Technology of Stomatology, Beijing Key Laboratory of Digital Stomatology No.22 Zhongguancun South Avenue, Haidian District Beijing 100081 P.R. China