1. Department of Periodontology, Faculty of Odontology University of Malmö Malmö Sweden
2. Division of Conservative Dentistry and Periodontology University Clinic of Dentistry, Medical University of Vienna Vienna Austria
3. Department of Periodontology, Dental Clinic, Faculty of Medicine Sigmund Freud University Vienna Vienna Austria
4. Section for Prosthetic Dentistry, Department of Dentistry and Oral Health Aarhus University Aarhus Denmark
5. Nordic Institute of Dental Materials, NIOM Oslo Norway
6. Department of Dental Materials, Faculty of Odontology University of Malmö Malmö Sweden