1. Department of Stomatology, The First Affiliated Hospital of Baotou Medical College, Inner Mongolia University of Science and Technology, Baotou, China.
2. Department of Stomatology, Baotou Eighth Hospital, Baotou, China.
3. Department of Stomatology, Hospital of FIRMACO, The Fourth Affiliated of Inner Mongolia Medical University, Baotou, China.
4. Zhinuo Dental Clinic, Baotou, China.