1. Faculty of Medicine and University Hospital Cologne, Polyclinic for Operative Dentistry and Periodontology, University of Cologne, D-50923 Cologne, Germany
2. Clinic for Early Neurological and Interdisciplinary Rehabilitation, St. Marien-Hospital, D-50668 Cologne, Germany
3. Department of Health, EUFH-European University of Applied Sciences, D-50996 Cologne, Germany