1. State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, China
2. Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
3. Biomaterials and Tissue Engineering Division, Department of Endodontics, Prosthodontics, and Operative Dentistry, University of Maryland Dental School, Baltimore, MD, USA