D Alexander1, J Hoffmann1, A Munz1, B Friedrich2, J Geis-Gerstorfer3, S Reinert1. 1. Department of Oral and Maxillofacial Surgery , 1,3Osianderstr. 2-8, 2Otfried-Muller-Str. 10, 72076 Tubingen, Germany. 2. Department of Internal Medicine IV , 1,3Osianderstr. 2-8, 2Otfried-Muller-Str. 10, 72076 Tubingen, Germany. 3. Department of Prosthodontics, Section Medical Materials and Technology, University Hospital Tubingen , 1,3Osianderstr. 2-8, 2Otfried-Muller-Str. 10, 72076 Tubingen, Germany.