1. Department of Prosthodontics, Aristotle University Faculty of Health Sciences, School of Dentistry, 54124 Thessaloniki, Greece
2. Division of Postgraduate Prosthodontics, Tufts University School of Dental Medicine, Boston, MA 02111, USA
3. Graduate Prosthodontics, Department of Restorative Sciences and Biomaterials, Boston University Henry M. Goldman School of Dentistry, Boston, MA 02118, USA