1. Population Health Sciences Institute, Newcastle University, Newcastle Upon Tyne, UK
2. Department of Primary Care and Population Health, Institute of Epidemiology and Health Care, University College London, UK
3. Faculty of Medical Sciences, Population Health Research Institute, St George’s University of London, UK
4. Department of Health Sciences, Amsterdam Public Health Research Institute, Vrije Universiteit, the Netherlands
5. Department of Orofacial Sciences, School of Dentistry, University of California, San Francisco
6. Department of Dental Public Health, School of Dental Medicine, University of Pittsburgh, Pennsylvania