1. Department of Prosthodontics; Kocaeli University School of Dentistry; Kocaeli Turkey
2. School of Dentistry, Department of Prosthodontics; Ege University; Izmir Turkey
3. Dental Materials Unit, Center for Dental and Oral Medicine, Clinic for Fixed and Removable Prosthodontics and Dental Materials Science; University of Zurich; Zurich Switzerland