1. From the Institute of Dentistry, University of Helsinki and Department of Oral and Maxillofacial Diseases, Helsinki University Central Hospital (P.J.P., S.A.), Finland; Umeå University (S.A.), Sweden; and Department of Epidemiology and Health Promotion (P.J., V.S.) and Department of Health and Functional Ability (G.A., T.P.), KTL-National Public Health Institute, Helsinki, Finland.