1. School of Dentistry, The University of Manchester; Department of Oral and Maxillofacial Surgery; Coupland III Building, Oxford Road Manchester UK M13 9PL
2. School of Dentistry, The University of Manchester; Cochrane Oral Health Group; Coupland III Building, Oxford Road Manchester UK M13 9PL
3. Academic Centre for Dentistry Amsterdam (ACTA); Social Dentistry and Behavioural Sciences; Gustav Mahlerlaan 3004 Amsterdam Netherlands 1081 LA
4. City Hospital; Oral and Maxillofacial Surgery; Birmingham UK