1. Department of Periodontology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China
2. Key Laboratory of Oral Biomedical Research of Zhejiang Province, Zhejiang University School of Stomatology, China
3. Clinic for Conservative Dentistry and Periodontology, School of Dental Medicine, Christian-Albrechts-Universität zu Kiel, Kiel 24105, Germany
4. Oral Medicine and Periodontology Department, Faculty of Oral and Dental Medicine, Cairo University, Cairo 11435, Egypt