1. Department of Buccofacial Prostheses; Faculty of Dentistry; Complutense University of Madrid (U.C.M.); Pza. Ramón y Cajal, s/n Madrid 28040 Spain
2. Department of Prosthetic Dentistry; University Dental School; Heath Park Cardiff CF14 4XY UK
3. Department of Dentistry for Adults; European University (U.E.); C/ Tajo, s/n, Villaviciosa de Odón Madrid 28670 Spain
4. Department of Adult Dental Health; University Dental School; Heath Park Cardiff CF14 4XY UK