1. Department of Restorative Dentistry, University of Illinois at Chicago, College of Dentistry, Chicago, Illinois 60612, United States
2. Department of Restorative Dental Sciences, Imam Abdulrahman Bin Faisal University, College of Dentistry, Dammam 34212, Saudi Arabia
3. Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas, (UNICAMP), Piracicaba 13414-903, São Paulo, Brazil
4. Department of Materials, University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
5. Department of Biomedical Sciences, University of Illinois, College of Medicine, Rockford, Illinois 61107, United States