1. School of Dentistry, The University of Manchester; Cochrane Oral Health Group; Coupland III Building, Oxford Road Manchester UK M13 9PL
2. Leeds Dental Institute; Fixed & Removable Prosthodontics; Clarendon Way Leeds UK LS2 9LU
3. School of Dentistry, The University of Manchester; Unit of Biomaterials Science; Higher Cambridge Street Manchester UK M15 6FH
4. The University of Liverpool; Department of Restorative Dentistry, School of Dental Sciences; Room 303, Liverpool University Dental Hospital Pembroke Place Liverpool UK L3 5PS