1. Department of Periodontology; Witten/Herdecke University; Witten Germany
2. Multi-disciplinary Treatment Center; Beijing Stomatological Hospital; Capital Medical University; Beijing China
3. Department of Oral Biology and Materials Science; Witten/Herdecke University; Witten Germany
4. Department of Maxillofacial Surgery; Rotes-Kreuz-Krankenhaus Kassel; Kassel Germany