1. Institute of Biochemistry, Faculty of Medicine, University of Ancona, Via Ranieri, 60100 Ancona, Italy
2. Department of Periodontology, School of Dentistry, University of Seville, Spain
3. Department of Microbiology, Eastman Dental Institute, University of London, UK
4. Department of Periodontology, Eastman Dental Institute, University of London, UK