1. Department of Operative Dentistry and Periodontology, Medical Center, Faculty of Medicine University of Freiburg Freiburg Germany
2. Northern Hessia Implant Center Hofgeismar Germany
3. Private Practice Stuttgart Germany
4. Institute for Medical Biometry and Statistics, Faculty of Medicine and Medical Center University of Freiburg Freiburg Germany
5. Department of Oral and Maxillofacial Surgery University Medical Center, University of Goettingen Goettingen Germany