1. Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, Michigan 48109-1078
2. Belize City Hospital, Belize City, Belize
3. Department of Dental Public Health Sciences, University of Washington, Seattle
4. Ylivieska Health Center, Ylivieska, Finland
5. Institute of Dentistry, University of Turku, Turku, Finland