1. Department of Preventive Dental Sciences, College of Dentistry, King Saud bin Abdulaziz University for Health Sciences, P.O. Box 3660, Riyadh 11481, Saudi Arabia
2. King Abdullah International Medical Research Center, Ministry of National Guard-Health Affairs, P.O. Box 3660, Riyadh 11481, Saudi Arabia
3. College of Dentistry, King Saud bin Abdulaziz University for Health Sciences, P.O. Box 3660, Riyadh 11481, Saudi Arabia
4. Department of Periodontics, King Abdulaziz Medical City, Ministry of National Guard-Health Affairs, P.O. Box 22490, Riyadh 11426, Saudi Arabia