1. Department of Stomatology, Zhongshan Hospital, Fudan University, Shanghai, China
2. Department of Stomatology, Xuhui Central Hospital, Shanghai, China
3. Department of Prosthodontics, School of Dentistry, Albert Ludwigs University, Freiburg, Germany
4. Department of Prosthodontics, Dental Medicine, Tufts University School, Boston, United States of America