Yousef Abdalla1, Liselotte Sonnesen2. 1. PhD Student, Section of Orthodontics, Department of Odontology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark, and Lecturer in Orthodontics, College of Medicine and Dentistry, James Cook University, Cairns, Australia. 2. Professor and Director of Postgraduate Program, Section of Orthodontics, Department of Odontology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.