Text and Data Mining valid from 2019-12-01
Received: 28 June 2019
Accepted: 1 November 2019
First Online: 9 December 2019
Ethics approval and consent to participate
: The study was approved by the Institutional Review Board of the Stomatological Hospital of Air Force Military Medical University(2016048) and Guangzhou Medical University(2019038).
: All sample data are from the CBCT database of relevant hospitals. This study is of a retrospective nature, so informed consent was waived.
: The authors declare that they have no competing interests.