1. Department of Periodontology, Center of Stomatology Xiangya Hospital, Central South University Changsha China
2. Department of Periodontology Shanghai Xuhui District Dental Center Shanghai China
3. National Clinical Research Center for Geriatric Disorders Xiangya Hospital Changsha China
4. Department of Oral and Maxillofacial Surgery, Center of Stomatology Xiangya Hospital, Central South University Changsha China
5. Hunan Key Laboratary of Aging Biology Xiangya Hospital, Central South University Changsha China