1. Department of Surgical, Oncological and Oral Sciences, University of Palermo, 90127 Palermo, Italy
2. Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties, University of Palermo, 90127 Palermo, Italy
3. Department of Restorative, Preventive and Paediatric Dentistry, University of Bern, 3012 Bern, Switzerland
4. Department of Surgery, Microsurgery and Medicine Sciences, School of Dentistry, University of Sassari, 07100 Sassari, Italy