Funding for this research was provided by:
Scientific Research Foundation for Young Teachers of XiangYa stomatological Hospital
Text and Data Mining valid from 2018-03-03
Received: 6 December 2016
Accepted: 21 February 2018
First Online: 3 March 2018
Compliance with ethical standards
: Our hospital’s ethics committee approved the study.
: The authors declare that they have no conflicts of interest.