1. Department of Orthodontics, Postgraduate Dental Education Center, Örebro , Sweden
2. Faculty of Medicine and Health, School of Medical Sciences, Örebro University , Örebro , Sweden
3. Department of Orthodontics, The Institute for Postgraduate Dental Education , Jönköping , Sweden
4. School of Health and Welfare, Jönköping University , Jönköping , Sweden
5. Clinical Epidemiology and Biostatistics, School of Medical Sciences, Örebro University , Örebro , Sweden