1. Department of Operative and Preventive Dentistry; Charité - Universitätsmedizin Berlin; Berlin Germany
2. Department of Preventive and Pediatric Dentistry; Universitätsmedizin Greifswald; Greifswald Germany
3. Department of Oral Sciences; Faculty of Dentistry; University of Otago; Otago New Zealand
4. Kiel Institute for the World Economy; Kiel Germany