1. Department of Periodontology, Operative and Preventive Dentistry; University Hospital Bonn; Bonn Germany
2. Cochrane Oral Health; Division of Dentistry, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester; Manchester UK
3. Unit of Periodontology and International Centre for Evidence-Based Oral Health; UCL Eastman Dental Institute; London UK
4. Department of Periodontology and Peri-implant Diseases; Philips University Marburg; Marburg Germany
5. Clinic for Prosthetic Dentistry; University Iuliu-Hatieganu; Cluj-Napoca Romania
6. Cochrane Oral Health, Division of Dentistry, School of Medical Sciences, Faculty of Biology, Medicine and Health; The University of Manchester; Manchester UK