1. Department of Oral and Maxillofacial Diseases, University of Helsinki, 00290 Helsinki, Finland
2. Department of Oral Pathology and Radiology, Faculty of Medicine, University of Turku, 20520 Turku, Finland
3. Division of Infections and Cancer Epidemiology, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
4. SMW Consultants, Ltd., 21620 Kaarina, Finland
5. Department of Obstetrics and Gynecology, University of Turku, Turku University Hospital, 20014 Turku, Finland
6. Department of Obstetrics and Gynecology, Faculty of Medicine and Health Technology, Tampere University, 33520 Tampere, Finland
7. Department of Obstetrics and Gynecology, Tampere University Hospital, 33100 Tampere, Finland
8. Department of Pathology, University of Turku, Turku University Hospital, 20520 Turku, Finland