1. Institute of Dentistry, P.O. Box 41, FIN-00014 University of Helsinki
2. Department of Oral and Dental Diseases, University of Kuopio, P.O. Box 1627, FIN-70211 Kuopio, Finland
3. Department of Community Health and General Practice, University of Kuopio, P.O. Box 1627, FIN-70211 Kuopio, Finland
4. Department of Community Health and General Practice, University of Kuopio, P.O. Box 1627, FIN-70211 Kuopio, Finland, Harjula Geriatric Hospital, P.O. Box 38, FIN-70101 Kuopio, Finland