1. Department of Clinical Dentistry; Faculty of Health Sciences; UiT the Arctic University of Norway; Tromsø Norway
2. The Public Dental Health Service Competence Centre of Northern Norway; Tromsø Norway
3. Academic Unit of Oral Health, Dentistry and Society; School of Clinical Dentistry; University of Sheffield; Sheffield UK
4. Department of Periodontology; Institute of Odontology; The Sahlgrenska Academy; University of Gothenburg; Gothenburg Sweden