1. Department of Stomatology, The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao 266003, P. R. China
2. School of Stomatology, Qingdao University, Qingdao 266003, P. R. China
3. Department of Endodontics in the first clinical division, Tianjin Stomatological Hospital, School of Medicine, Nankai University, Tianjin 300041, P. R. China
4. Tianjin Key Laboratory of Oral and Maxillofacial Function Reconstruction, Tianjin 300041, P. R. China
5. School of Materials Science and Engineering, National Institute for Advanced Materials, Nankai University, Tianjin 300350, P. R. China
6. Department of Oramaxillofacial-Head and Neck Surgery, Tianjin Stomatological Hospital, School of Medicine, Nankai University, Tianjin 300041, P. R. China
7. College of Pharmacy, Xinjiang Medical University, Urumqi 830017, P. R. China