1. Oral Biology Department, Faculty of Dentistry, Cairo University, Cairo, Egypt
2. Stem Cells and Tissue Engineering Research Group, Faculty of Dentistry, Cairo University, Cairo, Egypt
3. Clinic for Conservative Dentistry and Periodontology, School of Dental Medicine, Christian Albrechts University, Kiel, Germany
4. Oral Medicine and Periodontology Department, Faculty of Dentistry, Cairo University, Cairo, Egypt