1. Department of Periodontology, Institute of Dentistry, University of Turku, 20014 Turku, Finland
2. Welfare Division, Oral Health Care, 20540 Turku, Finland
3. Department of Oral and Maxillofacial Diseases, Clinicum, Faculty of Medicine, University of Helsinki and Helsinki University Hospital, 00014 Helsinki, Finland
4. Department of Pathology, Medicum, Faculty of Medicine, University of Helsinki and HUS Diagnostic Center, HUSLAB, Helsinki University Hospital, 00260 Helsinki, Finland
5. Oral and Maxillofacial Diseases, University of Helsinki, 00014 Helsinki, Finland
6. Institute of Dentistry, University of Eastern Finland, 70210 Kuopio, Finland
7. Institute of Oral Biology, Faculty of Dentistry, University of Oslo, 0372 Oslo, Norway