1. Department of Pedodontics and Orthodontics, Institute of Dentistry, University of Helsinki, Helsinki, Finland
2. Department of Oral and Maxillofacial Diseases, Helsinki University Central Hospital, Helsinki, Finland
3. Department of Laboratory Medicine, Desio Hospital, University of Milano, Bicocca, Italy
4. Department of Oral Pathology, Institute of Dentistry, University of Helsinki, and Department of Pathology, Helsinki University Central Hospital, Helsinki, Finland
5. Department of Radiology, Institute of Dentistry, University of Helsinki, Helsinki, Finland
6. Division of Laboratory Sciences, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
7. Department of Environmental Health, National Public Health Institute, and Department of Public Health and General Practice, University of Kuopio, Kuopio, Finland