1. King’s College London, Dental Institute, Central Office, Guy’s Tower, Guy’s Hospital, London SE1 9RT, UK
2. University of Michigan, School of Dentistry, Department of Cariology, Restorative Sciences, and Endodontics, Room 2353, 1011 N. University Avenue, Ann Arbor, MI 48109-1078, USA
3. University of British Columbia, Faculty of Dentistry, Department of Oral Biological and Medical Sciences, J.B. Macdonald Building, 2199 Wesbrook Mall, Vancouver, BC V6T 1Z3, Canada
4. Newcastle University, School of Dental Science and Centre for Oral Health Services Research, Restorative Dentistry Department, Newcastle upon Tyne NE2 4BW, UK