1. State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Disease, Department of Prosthodontics; West China Hospital of Stomatology, Sichuan University; Chengdu China
2. Department of Periodontics and Oral Medicine, School of Dentistry; University of Michigan; Ann Arbor Michigan
3. Department of Biologic and Materials Sciences, Division of Prosthodontics, School of Dentistry; University of Michigan; Ann Arbor Michigan