[1] Univ Bern, Dept Orthodont & Dentofacial Orthoped, CH-3010 Bern, Switzerland
[2] Palacky Univ, Dept Orthodont, Fac Med, Olomouc 77200, Czech Republic
[3] Univ Manchester, Sch Dent, Manchester M15 6FH, Lancs, England
[4] Inst Mother & Child Hlth, Lab Speech Pathol & Upper Airway Endoscopy, PL-01211 Warsaw, Poland
[5] Univ Clin Hosp, Dept Otolaryngol & Maxillofacial Surg, PL-10082 Olsztyn, Poland