1. S Al-Mubarak (corresponding author) Dental Department, King Faisal Specialist Hospital and Research Center, PO Box 3354, Riyadh 11211, Saudi Arabia;
2. Dental Department, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia;
3. College of Dentistry, King Saud University, Riyadh, Saudi Arabia;
4. Research Center, Sultan Bin Abdulaziz Humanitarian City, Riyadh, Saudi Arabia;
5. Department of Dental Public Health, College of Dentistry, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
6. Prince Abdulrahman Bin Abdulaziz Institute for Higher Dental Studies, Riyadh, Saudi Arabia;
7. Department of Periodontics and Endodontics, School of Dental Medicine, State University of New York at Buffalo, Buffalo, New York, USA