1. Department of Oral Health Policy & Epidemiology, Harvard School of Dental Medicine, 188 Longwood Ave., Boston, MA 02115, USA;
2. Department of Epidemiology, Harvard School of Public Health, Boston,
MA 02115, USA;
3. Department of Community Dentistry, Faculty of Dentistry, Khon Kaen
University, Khon Kaen 40002, Thailand;
4. Craniofacial Epidemiology and Genetics Branch, National Institute of
Dental and Craniofacial Research, Bethesda, MD 20892-6401, USA; and
5. Oral Medicine Department, A. Sygros Hospital, University of Athens
Medical School, 37 Ipsiladou Street, Athens 10676, Greece;