1. Institute of Dentistry University of Eastern Finland Kuopio Finland
2. Department of Oral and Maxillofacial Diseases Kuopio University Hospital Kuopio Finland
3. Department of Oral and Maxillofacial Surgery Oulu University Hospital Oulu Finland
4. Research Unit of Oral Health Sciences Medical Research Centre Oulu (MRC Oulu) University of Oulu Oulu Finland
5. Unit of Public Health Evaluation and Projection National Institute for Health and Welfare (THL ) Helsinki Finland