[1] Health Services Research,Department of Oral Medicine
[2] UCL Eastman Dental Institute,Department of Oral and Maxillofacial Pathology
[3] UCL Eastman Dental Institute,undefined
[4] The School of Clinical Dentistry,undefined
[5] The University of Sheffield,undefined
[6] Claremont Crescent,undefined
[7] Cancer Research UK Epidemiology and Genetic Group,undefined
[8] London School of Hygiene and Tropical Medicine,undefined