1. Department of Periodontics, Stomatological Hospital, Southern Medical University, Guangzhou, Guangdong 510280, P.R. China
2. Department of Orthodontics, Guangdong Xieda Stomatological Hospital, Guangzhou, Guangdong 510399, P.R. China
3. Department of Orthodontics, Taike Dentalcare Clinic, Guangzhou, Guangdong 510000, P.R. China
4. Department of Endodontics, Stomatological Hospital, Guangzhou, Guangdong 510515, P.R. China
5. Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong 510515, P.R. China