1. Department of Prosthodontics,, Faculty of Dentistry, Sana’a University, Sana’a, Yemen
2. Department of Prosthodontics, Faculty of Dentistry, Sana’a University, Sana'a, Yemen
3. Department of Allied Dental Sciences, College of Applied Medical Sciences in Khamis Mushait, King Khalid University, Khamis Mushait, Saudi Arabia
4. Prosthetic Department, College of Dentistry, King Khalid University, Abha, Saudi Arabia
5. Department of Prosthodontics, Faculty of Dentistry, Taif University, Taif, Saudi Arabia
6. Department of Prosthetic Dental Science, College of Dentistry, Jazan University, Jazan, Saudi Arabia
7. Department of Prosthodontics, College of Stomatology, Xi’an Jiaotong University, Xi’an, Shaanxi, China (mainland)
8. Preventive Dentistry Department, College of Dentistry, Jazan University, Jazan, Saudi Arabia