1. Institute of Dentistry, University of Eastern Finland, Kuopio, Finland
2. Research Unit of Oral Health Sciences, University of Oulu, Oulu, Finland
3. Medical Research Center, Oulu University Hospital and University of Oulu, Oulu, Finland
4. Finnish National Institute for Health and Welfare, Helsinki, Finland
5. Institute of Dentistry, Kuopio University Hospital, Kuopio, Finland
6. Department of Public Health and Welfare, National Institute for Health and Welfare, Helsinki, Finland