1. Department of Prosthetic Dentistry, Institute for Postgraduate Dental Education, Jönköping, Sweden;
2. Department of Prosthodontics/Dental Materials Science, Institute of Odontology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden;
3. Specialist Dental Clinic, Folktandvården Sörmland AB, The Mälar Hospital, Eskilstuna, Sweden;
4. Centre for Clinical Research Sörmland, Uppsala University, Eskilstuna, Sweden