M Aljayousi1, S Al-Khateeb2, S Badran3, E S Abu Alhaija4. 1. Division of Orthodontics, Department of Preventive Dentistry, Faculty of Dentistry, Jordan University of Science and Technology, P.O. Box 3030, Irbid, 22110, Jordan. 2. Division of Orthodontics, Department of Preventive Dentistry, Faculty of Dentistry, Jordan University of Science and Technology, P.O. Box 3030, Irbid, 22110, Jordan. susank@just.edu.jo. 3. Department of Orthodontics, Faculty of Dentistry, The University of Jordan, Amman, Jordan. 4. College of Dental Medicine, Qatar University, P.O. Box 2713, Doha, Qatar.