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