1. Public Health School, Gansu University of Chinese Medicine, Lanzhou, Gansu 730000, China
2. Affiliated Hospital of Gansu University of Chinese Medicine, Lanzhou, Gansu 730000, China
3. Center of Research and Experiment, Gansu University of Chinese Medicine, Lanzhou, Gansu 730000, China
4. School & Hospital of Stomatology Lanzhou University, Lanzhou, Gansu 730000, China