1. Department of Prosthodontics, School of Dentistry, Harbin Medical University, Harbin, Heilongjiang, China
2. Faculty of Dentistry, University of Hong Kong, Hong Kong, China
3. Dr D Y Patil Dental College and Hospital, Pimpri, Pune, India
4. Department of Cariology, Endodontology and Periodontology, University Leipzig, Leipzig, Saxon, Germany