1. Department of Prosthodontics and Biomaterials; Centre for Implantology; Medical Faculty; RWTH Aachen University; Aachen Germany
2. Department of Prosthodontics; University of Heidelberg; Heidelberg Germany
3. Institute of Medical Statistics; RWTH Aachen University; Aachen Germany
4. Institute of Immunology; RWTH Aachen University; Aachen Germany