1. University of Salford; Directorate of Psychology and Public Health, School of Health Sciences; Allerton Building Frederick Road Campus Salford Greater Manchester UK M6 6PU
2. The University of Manchester; School of Dentistry; Coupland 3 Building Oxford Road Manchester Greater Manchester UK M13 9PL
3. School of Health Sciences, University of Salford; World Health Organization Collaborating Centre for Research on Oral Health in Deprived Communities; Allerton Building Fredrick Road Campus Salford Greater Manchester UK M6 6PU
4. University of Liverpool; Department of Biostatistics, Institute of Translational Medicine, Faculty of Health and Life Sciences; Liverpool UK
5. Queen Mary University of London; Barts and The London School of Medicine and Dentistry; Turner Street London UK E1 2AD