1. Dental surgery Dr Kopp , Güstrow , Germany;
2. Department of Material Science and Medical Engineering , University of Rostock, Germany; , ,
3. Institute of Implant Technology and Biomaterials , Rostock-Warnemünde , Germany;
4. University of Regensburg , Department of Prosthetic Dentistry, Regensburg , Germany;
5. University of Rostock , Medical Faculty, Department of Prosthodontics and Materials Science, Rostock , Germany;
6. University of Tübingen , Department of Medical Material Science and Technology, Tübingen , Germany;