1. Department of Oral and Maxillofacial Surgery; Radboud University Medical Center; Nijmegen The Netherlands
2. Department of Oral and Maxillofacial Surgery and Special Dental Care; University Medical Center Utrecht; Utrecht The Netherlands
3. Section Biostatistics; Department for Health Evidence; Radboud University Medical Center; Nijmegen The Netherlands
4. Julius Center Sciences; University Medical Center Utrecht; Utrecht The Netherlands