1. Department of Periodontology, Shenzhen Stomatological Hospital, Southern Medical University, Shenzhen, Guangdong 518000, P.R. China
2. Department of Periodontology, School of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Disease, Shenyang, Liaoning 110002, P.R. China
3. Department of Periodontics and Oral Biology, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Disease, Shenyang, Liaoning 110002, P.R. China