1. Research Unit of Oral Health Sciences, University of Oulu, Oulu, Finland
2. Department of Community Dentistry, University of Turku, Turku, Finland
3. Center for Population Health Research, Turku University Hospital, University of Turku, Turku, Finland
4. Oral and Maxillofacial Department, Medical Research Center Oulu, Oulu University Hospital, Oulu, Finland
5. Faculty of Medicine, University of Oulu, Oulu, Finland