1. Department of Dental Materials and Fixed Prosthodontics of the University of Siena, Tuscan School of Dental Medicine, University of Firenze and Siena, Policlinico ‘Le Scotte’, viale Bracci, Siena 53100, Italy
2. Department of Endodontics, College of Dentistry, Georgia Health Sciences University, 1120 15th Street, Augusta, GA, USA
3. Department of Medical Sciences, University of Trieste, Piazza, Ospedale 1, Trieste 34129, Italy
4. Department of Oral Sciences, ‘Sapienza’ University of Rome, viale Regina Elena 287/A, Roma, Italy