1. State Key Laboratory of Oral Diseases and National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
2. Department of Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
3. Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, China.