1. Department of Prosthetic Dentistry and Oral Function; Faculty of Dentistry; Institute of Clinical Dentistry; University of Oslo; Oslo Norway
2. Specialist Clinic of Prosthetic Dentistry; Public Dental Health Service; Västra Götaland; Mölndal Hospital; Mölndal Sweden
3. Department of Prosthetic Dentistry/Dental Materials Science; Institute of Odontology; The Sahlgrenska Academy; University of Gothenburg; Gothenburg Sweden