1. Prosthodontics Division, Schulich School of Medicine and Dentistry, Western University, London, Canada
2. Department of Clinical Dental Sciences, College of Dentistry, Princess Nourah bint Abdulrahman University, P. O. Box 84428, Riyadh 11671, Saudi Arabia
3. Mathematical Science Department, College of Science, Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia
4. Department of Preventive Dental Sciences, College of Dentistry, Princess Nourah bint Abdulrahman University, P. O. Box 84428, Riyadh 11671, Saudi Arabia