1. Clinic of Fixed and Removable Prosthodontics and Dental Material Science; University of Zurich; Zurich Switzerland
2. Department of Oral Surgery and Radiology; School of Dentistry; Medical University Graz; Graz Austria
3. Clinic of Preventive Dentistry, Periodontology and Cariology; Center of Dental Medicine; University of Zurich; Zurich Switzerland
4. Department of Periodontology; Research Institute for Periodontal Regeneration; Yonsei University College of Dentistry; Seoul Korea