Text and Data Mining valid from 2019-03-07
Received: 31 October 2018
Accepted: 25 February 2019
First Online: 7 March 2019
Ethics approval and consent to participate
: The current retrospective study was approved by the review board of Tokyo Medical and Dental University (1777). The informed consent was obtained for each patient.
: Not applicable.
: The authors declare that they have no competing interests.
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