1. Department of Operative Dentistry and Endodontics; School of Stomatology Fourth Military Medical University; Xi'an China
2. Division of Training; Fourth Military Medical University; Xi'an China
3. Department of Pulp Biology and Endodontics; Graduate School Tokyo Medical and Dental University; Tokyo Japan
4. Center for Dental Research Loma; Linda University School of Dentistry; Loma Linda CA