Funding for this research was provided by:
National Research Foundation of Korea (2016R1A2B4007286, 2016-929358)
Text and Data Mining valid from 2018-03-21
Received: 12 July 2017
Accepted: 14 March 2018
First Online: 21 March 2018
Ethics approval and consent to participate
: This study was performed based on the re-analysis of data from two previous papers the corresponding author (HSK) published. Both previous studies were approved by the Institutional Review Board of the Seoul National University Dental Hospital (CRI08004 on 25 January, 2008 and CRI13012 on 8 August, 2013, respectively), and informed consent was obtained from all participants.
: Not applicable.
: The authors declare that they have no competing interests.
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