1. Periodontology Unit, Vita-Salute San Raffaele University, 20132 Milan, Italy
2. Section of Periodontology, Department of Dental and Maxillofacial Sciences, Sapienza, University of Rome, 00161 Rome, Italy
3. Private Practice, 00187 Rome, Italy
4. Private Practice, Castletown, Isle of Man IM9 1AB, UK
5. Department of Surgery and Translational Medicine, University of Florence, 50121 Florence, Italy