1. Center for Dentistry and Oral Hygiene, Department of Oral Health and Clinical Epidemiologie; University Medical Center Groningen, University of Groningen; Groningen The Netherlands
2. Center for Rehabilitation, Department of Rehabilitation; University Medical Center Groningen, University of Groningen; Groningen The Netherlands
3. Health Sciences, Community and Occupational Medicine; University Medical Center Groningen, University of Groningen; Groningen The Netherlands