1. Department of Endodontics and Operative Dentistry I, School and Hospital of Stomatology, Fujian Medical University, Fujian, China.
2. Comprehensive Dental Care, Endodontics, Faculty of Dentistry, The University of Hong Kong, Prince Philip Dental Hospital, Hong Kong SAR, China.
3. Department of Stomatology, Air Force General Hospital of the PLA, Haidian District, Beijing, China.