1. Shanxi Medical University School and Hospital of Stomatology, Taiyuan, China;
2. Department of Mechanical and Aerospace Engineering, University of Missouri, Columbia, MO, USA;
3. Department of Prosthodontics, Beijing Stomatological Hospital and School of Stomatology, Capital Medical University, Beijing, China;
4. First Clinical Division, Peking University Hospital of Stomatology, Beijing, China