1. Department of Orthodontics and Craniofacial Biology, Kasprzaka Str. 17a, 01-211 Warsaw, Poland
2. Institute of Mother and Child, Department of Pediatric Surgery, Kasprzaka Str. 17a, 01-211 Warsaw, Poland
3. Palacky University, Department of Orthodontics, Palackého 12, 772 00 Olomouc, Czech Republic
4. Cleft Palate Craniofacial Unit, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands
5. University of Bern, Department of Orthodontics and Dentofacial Orthopedics, Freiburgstr. 7, CH-3010 Bern, Switzerland