1. Department of Oral Function and Prosthetic Dentistry, University of Nijmegen
2. Department of Cariology and Endodontology, University of Nijmegen
3. Department of Medical Statistics, University of Nijmegen
4. Department of Community Dental Health and Epidemiology, TNO Institute for Preventive Health Care, Leiden, TRIKON-Institute for Dental Clinical Research, University of Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
5. Department of Oral Function and Prosthetic Dentistry