Funding for this research was provided by:
Japan Society for the Promotion of Science (25463266 and 17K12063)
Text and Data Mining valid from 2019-07-12
Received: 6 April 2018
Accepted: 3 July 2019
First Online: 12 July 2019
Ethics approval and consent to participate
: The study protocol was reviewed and approved by both the Ethics Committee at the Nippon Dental University School of Life Dentistry (NDU-T2011–21) and the local education authority and conformed to the guidelines of the Declaration of Helsinki. The participants and their parents provided written informed consent prior to participation.
: Not applicable.
: The authors declare that they have no competing interests.