1. Nordic School of Public Health, Gothenburg, Sweden
2. Department of Cariology, Institute of Dentistry, Turku University, Turku, Finl
3. Garrison Hospital of Sodankyla, Sodankyla, Finland
4. Department of Odontology Cariology, Umea University, Sweden,
5. Department of Medicine, Turku University Central Hospital, Turku, Finland,
6. Department of Medical Microbiology, Turku University, Turku, Finland