Funding for this research was provided by:
National Natural Science Foundation of China (81801310)
Basic research program of natural science in shaanxi province (2020JQ-561)
Received: 28 April 2020
Accepted: 7 September 2020
First Online: 11 September 2020
Ethics approval and consent to participate
: Approved by the medical ethics committee of Affiliated Stomatology Hospital of Xi’an Jiaotong University, this study was determined to be a regular pedagogical practice, while not human subject research and no personal information was involved in the study (xjkqll2017–019). Verbal consent was obtained by the students before the study.
: Not applicable.
: The authors declare that they have no conflict of interest concerning this article.