1. a DDS, Specialist in Orthodontics, The County Orthodontic Clinic in Borås, Borås, Sweden.b Associate Professor, Department of Orthodontics, Institution of Odontology, Gothenburg, Sweden.Corresponding author: Dr Heidrun Kjellberg, Department of Orthodontics, Institution of Odontology, Medicinareg 12A Gothenburg, Västra Götaland SE-413 90 Sweden (heidrun.kjellberg@vgregion.se)