1. Oral Medicine and Periodontology Department, Faculty of Dentistry, Postal Code: 11553, Cairo University, Cairo, Egypt
2. Oral Medicine and Periodontology Department, Faculty of Dentistry, The British University in Egypt, Postal Code: 11837, El- Sherouk, Egypt
3. Oral Medicine and Periodontology Department, Faculty of Dentistry, Al-Ahram Canadian, 4th Industrial Zone, Banks Complex, 6th of October City (2), Giza Governorate 12563, Egypt