Funding for this research was provided by:
Seoul National University (Research Resettlement Fund)
Received: 25 September 2019
Accepted: 8 December 2019
First Online: 30 December 2019
Ethics approval and consent to participate
: The study was approved by the Institutional Review Board (IRB) of Seoul National University School of Dentistry (IRB No. S-D20180034). All participants were aware that they were taking part in this research and gave informed consent in addition to confirming that they would allow us to use their collected data anonymously for publication. All the data were anonymously collected and analyzed.
: Not Applicable.
: The authors declare that they have no competing interests. The first two authors contributed equally to this work and share first authorship and the last two authors worked as co-correspondents.