Funding for this research was provided by:
National Natural Science Foundation of China (NSFC 81771027, NSFC 81970979)
Article History
Received: 22 October 2019
Accepted: 10 February 2020
First Online: 17 February 2020
Ethics approval and consent to participate
: This study was approved by the Biomedical Ethics Committee of Peking University School and Hospital of Stomatology (No: PKUSSIRB-201946086). We declare that written informed consent was obtained from all participants included in the study.
: Not applicable.
: The authors declare that they have no competing interests.