Received: 2 July 2019
Accepted: 16 October 2019
First Online: 27 November 2019
Ethics approval and consent to participate
: Ethical approval was obtained from the Chonnam National University Dental Hospital Institutional Review Board (IRB CNUDH-2019-010). No consent to participate was necessary since the data used in this study did not include information on personal identification.
: Not applicable.
: The authors declare that they have no competing interests.