1. Department of Prosthodontics, Xiangya Stomatological Hospital & School of Stomatology, Central South University, Changsha, China
2. Department of Stomatology, Hunan University of Medicine, Hunan, China
3. Department of Stomatology, The Second Xiangya Hospital, Central South University, Changsha, China
4. Department of Stomatology, Xiangya Hospital, Central South University, Changsha, China