1. Department of Periodontology; Center for Dental, Oral, and Maxillofacial Medicine (Carolinum); Johann Wolfgang Goethe-University Frankfurt am Main; Frankfurt am Main Germany
2. Section of Periodontology; Department of Operative Dentistry and Periodontology; University Medical Center Freiburg; Dental School and Hospital; Freiburg Germany
3. Department of Oral Surgery and Implantology; Center for Dental, Oral, and Maxillofacial Medicine (Carolinum); Johann Wolfgang Goethe-University Frankfurt am Main; Frankfurt am Main Germany