Josef Kucera1, Jan Streblov2, Ivo Marek3, Tomas Hanzelka4. 1. Department of Orthodontics, First Faculty of Medicine, Charles University, Prague, Czech Republic. 2. Private Practice in Prague, Czech Republic. 3. Department of Orthodontics, Palacky University, Palackeho 12, Olomouc 772 00, Czech Republic. ortho.marek@email.cz. 4. Department of Orthodontics, First Faculty of Medicine, Charles University.