Received: 12 April 2021
Accepted: 7 July 2021
First Online: 16 July 2021
: This study was approved by the Peking University School and Hospital of Stomatology Ethics Committee with the number PKUSSIRB-201944061. All the participants had signed the informed consent in written form before the study commenced.
: Not applicable.
: The authors declare that they have no competing interests.