1. Department of Orthodontics and Dentofacial Orthopedics, University of Bern, Freiburgstrasse 7, 3010 Bern, Switzerland
2. Department of Orthodontics, School of Dentistry, University of Athens, 2 Thivon Street, Goudi, 115 27 Athens, Greece
3. Department of Orthodontics, University of Geneva, Rue Barthélemy-Menn 19, 1205 Geneva, Switzerland