1. Unit of Dentistry and Oral Surgery; Department of Surgical & Medical Pathology; University of Pisa; Pisa Italy
2. Section of Graduate Periodontology; University Complutense; Madrid Spain
3. ETEP (Etiology and Therapy of Periodontal Diseases) Research Group; University Complutense; Madrid Spain
4. School of Dentistry; The University of Manchester; Manchester UK
5. School of Dentistry; University of Athens; Athens Greece