1. West Virginia University, Morgantown, WV, USA
2. University of Washington, Seattle, WA, USA
3. University of Sheffield, Sheffield, S. Yorkshire, UK
4. Boston University, Henry M. Goldman School of Dental Medicine, Boston, MA, USA
5. University of Pittsburgh, Pittsburgh, PA, USA
6. The University of Manchester, Manchester, UK
7. University of Hong Kong Faculty of Dentistry, Hong Kong
8. Kings College London, London, England, UK