1. Department of Stomatology, The Affiliated Hospital of Qingdao University Qingdao University Qingdao China
2. Minnesota Dental Research Center for Biomaterials and Biomechanics, School of Dentistry University of Minnesota Minneapolis Minnesota USA
3. Applied Oral Sciences and Community Dental Care, Faculty of Dentistry The University of Hong Kong Hong Kong S.A.R. China
4. Department of Cariology and Endodontology Peking University School and Hospital of Stomatology Beijing China