Funding for this research was provided by:
Project of Science and Technology Research from Department of Education of Liaoning Province (LK201607)
Article History
Received: 19 November 2018
Accepted: 1 July 2019
First Online: 13 July 2019
Compliance with ethical standards
:
: The authors declare that they have no conflict of interest.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the Ethics Committee of the School of Stomatology, China Medical University (2016-6), and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
: For this type of study, formal consent is not required.