1. Division of Prosthodontics, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
2. Clinical Dental Science Department, College of Dentistry, Princess Nourah Bint Abdulrahman University, Riyadh, Saudi Arabia
3. Department of Fixed Prosthodontics, Faculty of Dentistry, Cairo University, Cairo, Egypt
4. Department of Medical Microbiology and Immunology, Faculty of Medicine, Cairo University, Cairo, Egypt