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, Prosthodontics and Special Dental Care; University of Utrecht; University Medical Center Utrecht; Utrecht the Netherlands
3. Department of Epidemiology; Health Technology Assessment Unit; University Medical Center Groningen; University of Groningen; Groningen the Netherlands
4. Department of Oral and Maxillofacial Surgery; 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