1. Department of Periodontology; Public Dental Health Service; Kristianstad Sweden
2. Department of Cariology; Institute of Odontology; Sahlgrenska Academy; University of Gothenburg; Gothenburg Sweden
3. Oral Health Centre of Expertise in Eastern Norway; Oslo Norway
4. Department of Periodontology; Centre for Oral Health Sciences; Malmö University; Malmö Sweden
5. Center for Oral Health; Department of Natural Science and Biomedicine; School of Health Sciences; Jönköping University; Jönköping Sweden