1. School of Dentistry, The University of Manchester; Department of Oral and Maxillofacial Surgery; Higher Cambridge Street Manchester UK M15 6FH
2. University of East Anglia; Norwich Medical School; Norwich Research Park Norwich UK NR4 7TJ
3. City Hospital; Oral and Maxillofacial Surgery; Birmingham UK
4. School of Dentistry, The University of Manchester; Cochrane Oral Health Group; Coupland 3 Building, Oxford Road Manchester UK M13 9PL
5. Academic Centre for Dentistry Amsterdam (ACTA); Social Dentistry and Behavioural Sciences; Gustav Mahlerlaan 3004 Amsterdam Netherlands 1081 LA