1. Department of Stomatology, Guangyuan Central Hospital, Guangyuan, Sichuan Province, China
2. Department of stomatology, Xiangyang Stomatological Hospital, Xiangyang City, Hubei Province, China
3. Department of stomatology, First Affiliated Hospital of Chengdu Medical College, Chengdu, Sichuan Province, China
4. Department of prosthodontics, WuXi Stomatology Hospital, Jiangsu Province, China