1. Community Dental Health Services Research Unit, Faculty of Dentistry,
University of Toronto, 124 Edward Street, Toronto, ON, Canada M5G 1G6;
2. Department of Dentistry, The Hospital for Sick Children, Toronto, ON,
Canada;
3. Department of Orthodontics, Faculty of Dentistry, University of
Toronto, Toronto, ON, Canada; and
4. Department of Clinical Epidemiology and Biostatistics, McMaster
University, Hamilton, ON, Canada;