1. 1 Department of Periodontology and Implantology, Stomatological Hospital, Southern Medical University, Guangzhou, China
2. 2 Department of Prosthodontics, Affiliated Stomatology Hospital of Guangzhou Medical University, Guangdong Engineering Research Center of Oral Restoration and Reconstruction, Guangzhou Key Laboratory of Basic and Applied Research of Oral Regenerative Medicine, Guangzhou, Guangdong, PR China