1. Department of Medicine, Surgery and Pharmacy, University of Sassari, Viale San Pietro 43, 07100 Sassari, Italy
2. Dental Unit, Azienda Ospedaliero-Universitaria di Sassari, 07100 Sassari, Italy
3. Department of Periodontology, School of Dental Medicine, University of Bern, Freiburgstrasse 3, 3010 Bern, Switzerland