1. Stomatology Department, Peking University Third Hospital, Beijing, China.
2. Transmission Electron Microscopy Laboratory, Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry and Molecular Engineering, Peking University, Beijing, China.
3. Department of Functional Materials, School of Materials Science and Engineering, Hebei Provincial Key Laboratory of Traffic Engineering Materials, Shijiazhuang Tiedao University, Shijiazhuang, China.
4. Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology, Beijing, China.
5. Microbiology Laboratory, Central Laboratory, Peking University School and Hospital of Stomatology, Beijing, China.