1. School of Dentistry, The University of Manchester; Department of Oral and Maxillofacial Surgery; Coupland 3 Building, Oxford Road Manchester UK M13 9PL
2. University of Bologna; Department of Oral and Dental Sciences; Via San Vitale 59 Bologna Italy 40125
3. School of Dentistry, The University of Manchester; Cochrane Oral Health Group; Coupland III Building, Oxford Road Manchester UK M13 9PL