1. Department of Prosthetics and Oral Function, Institute of Clinical Dentistry, Faculty of Dentistry University of Oslo Oslo Norway
2. Department of Periodontology, Institute of Clinical Dentistry, Faculty of Dentistry University of Oslo Oslo Norway
3. Department of Periodontology, Faculty of Odontology Malmö University Malmö Sweden
4. Department of Periodontology Blekinge Hospital Karlskrona Sweden
5. Department of General Practice University of Oslo Oslo Norway
6. Department of Periodontology, Faculty of Medicine and Health, School of Medical Sciences Orebro University Orebro Sweden
7. Private Practice Stavanger Norway