1. Department of Stomatology, Ningxia Medical University Affiliated Hospital, Yinchuan, Ningxia Province, People's Republic of China.
2. Department of Stomatology, Ningxia People's Hospital, Yinchuan, Ningxia Province, People's Republic of China.
3. Department of Neuroscience, Uppsala Biomedicine Center (BMC), Uppsala University, Uppsala, Sweden.