1. Division of Periodontology, Department of Developmental and Surgical Sciences, School of Dentistry University of Minnesota Minneapolis Minnesota USA
2. Department of Preventive Dentistry, Periodontology and Implant Biology, School of Dentistry Aristotle University of Thessaloniki Thessaloniki Greece
3. Centre for Oral Immunobiology and Regenerative Medicine and Centre for Oral Clinical Research, Institute of Dentistry Queen Mary University London (QMUL) London UK