Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
The first and second authors, Jing Wang and Shujun Song, respectively, should be indicated as having contributed equally to the paper. In addition, affiliation number 1 for the first and seventh authors. The correct affiliation is: Department of Orthodontics, College of Stomatology, Fourth Military Medical University, Xin Cheng District, Xi’an, China.
Competing Interests: No competing interests declared.
