1. Division of Population and Patient Health; King's College London Dental Institute at Guy's, King's College, and St. Thomas' Hospitals; London UK
2. Stomatology Hospital; Guangxi Medical University; Guangxi China
3. Department of Preventive Dentistry; Stomatology College; Jilin University; Changchun China
4. Department of Preventive Dentistry; School and Hospital of Stomatology; Wuhan University; Wuhan China
5. Department of Preventive Dentistry; Stomatological Hospital; Xi'an JiaoTong University; Xi'an China