Funding for this research was provided by:
Science Foundation for Youth Scholar of Peking University School and Hospital of Stomatology ((No. PKUSS20160109))
Article History
Received: 30 September 2018
Revised: 14 December 2018
Accepted: 22 December 2018
First Online: 2 January 2019
Compliance with ethical standards
:
: None of the authors has a conflict of interest to declare.