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