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