1. Beijing Key Laboratory of Tooth Regeneration and Function Reconstruction, Capital Medical University School of Stomatology, Beijing, P. R. China
2. State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, P. R. China
3. Department of Oral and Maxillofacial Surgery, Xiangya Hospital, Central South University, Shangsha, China
4. Department of Biochemistry and Molecular Biology, Capital Medical University School of Basic Medical Sciences, Beijing, P. R. China