Funding for this research was provided by:
Pusan National University
Text and Data Mining valid from 2019-11-22
Received: 14 August 2019
Accepted: 25 October 2019
First Online: 22 November 2019
Ethics approval and consent to participate
: The present study was reviewed and approved by the Institutional Review Board of Pusan national university dental hospital for scientific and ethical integrity (approval no. PNUDH-2018-043).
: Not applicable.
: The authors declare that they have no competing interests.