1. 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. Department of Oral & Maxillofacial Surgery and Special Dental Care; University Medical Center Utrecht, University of Utrecht; Utrecht the Netherlands
3. Department of Oral and Maxillofacial Surgery; University Medical Center Groningen, University of Groningen; Groningen the Netherlands
4. 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; Nieuwegein the Netherlands