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.