1. Department of Orthodontics Center for Dental and Oral Medicine University Medical Center Hamburg‐Eppendorf Martinistraße 52 20246 Hamburg Germany
2. Department of Pediatrics University Medical Center Hamburg‐Eppendorf Martinistraße 52 20246 Hamburg Germany
3. Department of Medical Biometry and Epidemiology University Medical Center Hamburg‐Eppendorf Martinistraße 52 20246 Hamburg Germany
4. Department of Orthodontics University Medical Center Leipzig Liebigstrasse 12 04103 Leipzig Germany