1. Department of Oral and Maxillofacial Surgery; University of Groningen and University Medical Center Groningen; Groningen; The Netherlands
2. Department of Rheumatology and Clinical Immunology; University Medical Center Groningen; University of Groningen; Groningen; The Netherlands
3. Department of Pathology and Medical Biology; University Medical Center Groningen; University of Groningen; Groningen; The Netherlands
4. Center for Dentistry and Oral Hygiene; University Medical Center Groningen; University of Groningen; Groningen; The Netherlands
5. Department of Neurology; University of Alabama; Birmingham; AL; USA