1. Associate professor, Department of Fixed and Removable Prosthodontics and Biomaterials; Center for Dentistry and Oral Hygiene, University Medical Center Groningen, University of Groningen; Groningen The Netherlands
2. Professor, Department of Fixed and Removable Prosthodontics and Biomaterials; Center for Dentistry and Oral Hygiene, University Medical Center Groningen, University of Groningen; Groningen The Netherlands
3. Professor, Department of Oral and Maxillofacial Surgery; University Medical Center Groningen, University of Groningen; Groningen The Netherlands
4. Associate professor, Department of Public and Individual Oral Health; Center for Dentistry and Oral Hygiene, University Medical Center Groningen, University of Groningen; Groningen the Netherlands
5. Department of Oral-Maxillofacial Surgery; Prosthodontics and Special Dental Care, St. Antonius Hospital; Nieuwegein The Netherlands