1. Laboratory for Biomaterials and Regenerative Medicine; Academy for Advanced Interdisciplinary Studies; Peking University; Beijing 100871 P. R. China
2. Central Laboratory and Department of Oral and Maxillofacial Surgery; School and Hospital of Stomatology; Peking University; Beijing 100081 P. R. China
3. School of Stomatology; Xuzhou Medical University; Xuzhou 221004 P. R. China
4. Department of Stomatology; Xuanwu Hospital; Capital Medical University; Beijing 100053 P. R. China