1. Department of Periodontology and Geriatric Dentistry; University of Oulu; Oulu Finland
2. Medical Informatics and Statistics Research Group; Oulu University; Oulu Finland
3. Department of Medical Microbiology and Immunology; Institute of Diagnostics, University of Oulu; Oulu Finland
4. Clinical Microbiology Laboratory; Oulu University Hospital; Oulu Finland
5. Health Centre of Oulu; Oulu Finland
6. Department of Primary Health Care; Vaasa Central Hospital; Vaasa Finland
7. Specialist Dental Health Care Unit; Oulu Finland
8. Medical Research Unit; Seinäjoki Central Hospital and University of Tampere; Tampere Finland
9. Laboratory; Oulu University Hospital; Oulu Finland
10. Department of Clinical Chemistry, Institute of Diagnostics; University of Oulu; Oulu Finland
11. Department of Bacteriology and Immunology, Laboratory Division (HUSLAB), Haartman Institute; Helsinki University Central Hospital, University of Helsinki; Helsinki Finland
12. Oral and Maxillofacial Department; Oulu University Hospital; Oulu Finland