1. Department of Dentistry and Oral Health Aarhus University Aarhus Denmark
2. Institute of Dentistry, University of Eastern Finland Kuopio Finland
3. Section of Community Dentistry University of Oslo Oslo Norway
4. Center for Translational Oral Research—Periodontology, Department of Clinical Dentistry University of Bergen Bergen Norway
5. School of Dentistry, Faculty of Medicine Pontificia Universidad Católica de Chile Santiago Chile