1. School of Dentistry, The University of Manchester; Cochrane Oral Health Group; Coupland III Building, Oxford Road Manchester UK M13 9PL
2. University of Dundee; Dental Health Services Research Unit; The Mackenzie Building Kirsty Semple Way Dundee Scotland UK DD2 4BF
3. University College Cork; Department of Epidemiology and Public Health; 4th Floor, Western Gateway Building, Western Road Cork Ireland