1. Department of Prosthetic Dentistry, Center for Dental and Oral Medicine University Medical Center Hamburg‐Eppendorf (UKE) Hamburg Germany
2. CMD‐Center Hamburg‐Eppendorf Hamburg Germany
3. Department of Prosthetic Dentistry and Dental Materials and Special Care, Center for Dental and Oral Medicine University of Leipzig Leipzig Germany
4. Department of General Oral Health Care, Academic Centre for Dentistry Amsterdam (ACTA) University of Amsterdam and Vrije Universiteit Amsterdam Amsterdam The Netherlands