1. Clinic for Conservative Dentistry and Periodontology, Christian-Albrechts-Universität Kiel, Kiel, Germany.
2. Oral Medicine and Periodontology Department, Faculty of Oral and Dental Medicine, Cairo University, Giza, Egypt.
3. Department of Operative and Preventive Dentistry, Charité–Universitätsmedizin Berlin, Berlin, Germany.
4. Institute for Medical Informatics and Statistics, Christian-Albrechts-Universität Kiel, Kiel, Germany.