1. a Associate Professor, Department of Orthodontics, Dental School of Westfälische Wilhelms-University, Münster, Germany
2. b Dental Student, Department of Orthodontics, Dental School of Westfälische Wilhelms-University, Münster, Germany
3. c Resident, Department of Orthodontics, Dental School of Westfälische Wilhelms-University, Münster, Germany
4. d Professor, Department of Operative Dentistry, Dental School of Westfälische Wilhelms-University, Münster, Germany