| Affiliation: | 1. Institute of Dentistry, University of Eastern Finland, Kuopio, Finland;2. Oral Health Care, Social Services and Health Care, Department of Social Services and Health Care, Helsinki, Finland;3. Oral and Maxillofacial Department, Kuopio University Hospital, Kuopio, Finland;4. Research Unit of Oral Health Sciences, Faculty of Medicine, University of Oulu, Oulu, Finland;5. Department of Oral and Maxillofacial Surgery, Medical Research Centre Oulu, Oulu University Hospital, Oulu, Finland;6. Korea Education Fund, Pyongyang city, Democratic People's Republic of Korea;7. Dental Faculty, Pyongyang Medical College, Kim Il Sung University, Pyongyang city, Democratic People's Republic of Korea;8. Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland |
