1. Department of Preventive and Biomedical Science, College of Dentistry, University of Science and Technology, Sana'a, Yemen
2. Department of Prosthetic Dental Science, College of Dentistry, Jazan University, Jazan, Saudi Arabia
3. Department of Restorative Dental Science, College of Dentistry, King Khalid University, Abha, Saudi Arabia
4. Fixed Prosthodontics Department, Faculty of Dentistry, Damascus University, Damascus, Syrian Arab Republic
5. Ministry of Health, Al-Dariyyah PHC Atheir Ghowagee, Jazan, Saudi Arabia
6. Dental Intern, College of Dentistry, Jazan University, Jazan, Saudi Arabia
7. Dental Intern, College of Dentistry, King Faisal University, Alahsa, Saudi Arabia
8. Dental Intern, College of Dentistery, King Faisal University, Dammam, Saudi Arabia
9. Orthodontic Department, Faculty of Dentistry, Thamar University, Thamar, Yemen
10. Department of Restorative and Prosthodontics, Collage of Dentistry, University of Science and Technology, Sana’a, Yemen
11. Private Dental Center, Sana'a, Yemen
12. Department of Preventive and Biomedical Science, College of Dentistry, University of Science and Technology, Aden, Yemen