1. Department of Dental Public Health Sciences, School of Dentistry Box 357475. University of Washington, Seattle, Washington 98195, USA, Department of Epidemiology, School of Dentistry Box 357475. University of Washington, Seattle, Washington 98195, USA
2. International Institute for Preventive Dentistry, University of Turku, Finland
3. Belize City Hospital, Belize City, Belize
4. Institute of Dentistry, University of Turku, Turku, Finland
5. Ylivieska Health Center, Ylivieska, Finland