1. Clinic of Fixed and Removable Prothodontics and Material Science; Center of Dental Medicine; University of Zurich; Zurich; Switzerland
2. Department of Restorative Dentistry and Biomaterials Sciences; Harvard School of Dental Medicine; Boston; MA; USA
3. Department of Prosthodontics and Operative Dentistry; Tufts University School of Dental Medicine; Boston; MA; USA