1. Health Administration of Kafr El-Zayat, Ministry of Health & Population, Kafr El-Zayat, Egypt.
2. Department of Oral Medicine, Periodontology, Diagnosis and Radiology.Faculty of Dentistry, Tanta, Egypt
3. Faculty of Oral and Dental Medicine, Kafr Elsheikh University, Kafr El-Shaikh, Egypt.
4. Department of Oral Medicine, Periodontology, Oral Diagnosis & Radiology, Faculty of Oral & Dental Medicine, Damanhour University, Damanhour, Egypt.