1. Stomatological Hospital School of Stomatology Southern Medical University Guangzhou 510280 China
2. Department of Dentistry the First Affiliated Hospital Sun Yat‐sen University Guangzhou 510080 China
3. Department of Stomatology The Third Affiliated Hospital Sun Yat‐sen University Guangzhou 510630 China
4. Department of Endodontics Jiangsu Key Laboratory of Oral Diseases Affiliated Hospital of Stomatology Nanjing Medical University Nanjing 210029 China
5. Division of Oral Biology and Medicine School of Dentistry University of California Los Angeles Los Angeles CA 90095 USA