Ma, Ruo-han
Li, Gang
Yin, Shuang
Sun, Yi
Li, Zi-li
Ma, Xu-chen
Funding for this research was provided by:
National Natural Science Foundation of China (81671034)
Article History
Received: 1 August 2019
Accepted: 16 October 2019
First Online: 15 November 2019
Compliance with ethical standards
:
: The authors declare that they have no conflict of interest.
: All procedures performed in the study involving human participants were in accordance with the ethical standards of Institutional Review Board of Peking University School and Hospital of Stomatology (PKUSSIRB-201944056) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
: Written informed consent was not required for this study because all of the included patients in the present investigation were collected retrospectively. Exemption of informed consent will not affect the rights and health of included patients. The application for free informed consent has been approved by the Institutional Review Board.