1. Section of Periodontology; Department of Conservative Dentistry; Clinic for Oral, Dental and Maxillofacial Diseases; University Hospital Heidelberg; Heidelberg Germany
2. Private Dental Practice; Weilburg Germany
3. Coordination Centre for Clinical Trials (KKS); University of Heidelberg; Heidelberg Germany
4. Institute of Medical Biometry and Informatics (IMBI); University of Heidelberg; Heidelberg Germany
5. Section of Endodontology; Department of Conservative Dentistry; Clinic for Oral, Dental and Maxillofacial Diseases; University Hospital Heidelberg; Heidelberg Germany
6. Department of Periodontology; Center of Dentistry and Oral Medicine (Carolinum); Johann Wolfgang Goethe-University Frankfurt; Frankfurt Germany