1. Department of Periodontology and Dental Research Institute; Translational Research Laboratory for Tissue Engineering (TTE); School of Dentistry; Seoul National University; Seoul Korea
2. Clinic of Fixed and Removable Prosthodontics and Dental Material Science; Center of Dental Medicine; University of Zurich; Zurich Switzerland
3. Department of Oral Surgery and Implantology; Carolinum; Goethe-University Frankfurt; Frankfurt Germany
4. US Army Advanced Education Program in Periodontics; Ft. Gordon GA USA