1. Department of Oral and Maxillofacial Surgery; University Medical Center Groningen; University of Groningen; Groningen The Netherlands
2. Department of Fixed and Removable Prosthodontics; Center for Dentistry and Oral Hygiene; Dental School; University Medical Center Groningen; University of Groningen; Groningen The Netherlands
3. Department of Periodontology; Center for Dentistry and Oral Hygiene; Dental School; University Medical Center Groningen; University of Groningen; Groningen The Netherlands