1. The Public Dental Health Service Competence Centre of Northern Norway Tromsø Norway
2. Department of Medical Biology, Faculty of Health Sciences UiT the Arctic University of Norway Tromsø Norway
3. The Public Dental Health Service Tromsø Norway
4. Department of Clinical Dentistry, Faculty of Health Sciences UiT the Arctic University of Norway Tromsø Norway
5. Department of Periodontology, Institute of Odontology The Sahlgrenska Academy at the University of Gothenburg Sweden