S S Virdee1, L D Addy2, P J Milward3, C D Lynch4. 1. Clinical Lecturer & Honorary Speciality Registrar in Restorative Dentistry Department of Restorative Dentistry, Birmingham Dental Hospital, Mill Pool Way, Birmingham, B5 7EG. 2. Consultant in Restorative Dentistry, Department of Restorative Dentistry, Cardiff Dental Hospital, Heath Park, Cardiff, CF14 4XY. 3. Senior Lecturer in Dental Technology and Biomaterial Sciences, Dental Education, Scholarship and Innovation, School of Dentistry, Cardiff University, Heath Park, Cardiff, CF14 4XY. 4. Professor of Restorative Dentistry, University Dental School & Hospital, University College Cork, Wilton, Cork, Ireland.