Lillemor Dimberg1, Kristina Arnrup2, Lars Bondemark3. 1. *Department of Orthodontics and. 2. **Dental Research Department, Postgraduate Dental Education Center, Region Örebro County, ***School of Health and Medical Sciences, Örebro University and. 3. ****Department of Orthodontics, Faculty of Odontology, Malmö University, Sweden.