1. Clinic of Fixed and Removable Prosthodontics and Dental Material Science; University of Zurich; Zurich Switzerland
2. Faculty of Science; International Research Collaborative; The University of Western Australia; Perth WA Australia
3. Department of Oral Surgery; Universitätsklinikum Düsseldorf; Düsseldorf Germany
4. Department of Oral Surgery and Implantology; Carolinum; Johann Wolfgang Goethe-University Frankfurt; Frankfurt Germany