1. Department of Oral and Maxillofacial Surgery, State Key Laboratory of Oral Disease & National Center for Stomatology & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan 610041, China
2. Department of Biomaterials Sciences and Prosthodontics, School of Dentistry, University of Michigan, Ann Arbor, MI, United States