1. Department of Periodontology, Operative and Preventive Dentistry University of Bonn Bonn Germany
2. Department of Periodontology and Peri‐implant Diseases University of Marburg Marburg Germany
3. School of Dental Medicine University Iuliu‐Hatieganu Cluj‐Napoca Romania
4. Department of Periodontology, School of Dental Medicine University of Bern Bern Switzerland