1. Department of Orthodontics and Dentofacial Orthopedics, University Hospital, LMU Munich, Munich, Germany
2. Department of Operative Dentistry and Periodontology, University Hospital, LMU Munich, Munich, Germany
3. Department of Orthodontics, Medical Center, Johannes Gutenberg University Mainz, Mainz, Germany
4. Department of Orthodontics, Hannover Medical School, Hannover, Germany
5. Department of Orthodontics, Heinrich-Heine-University, Duesseldorf, Germany