1. Institute of Dentistry, University of Eastern Finland, Kuopio, Finland;
2. City of Äänekoski, Public Health Center, Oral Health Care Services, Äänekoski, Finland;
3. Oral and Maxillofacial Department, Kuopio University Hospital, Kuopio, Finland;
4. Research Unit of Oral Health Sciences, University of Oulu, Oulu, Finland;
5. Oral and Maxillofacial Department, Medical Research Center Oulu, Oulu University Hospital, Oulu, Finland