1. Unit of Dental Hygiene, Section of Dentistry, Department of Clinical, Surgical, Diagnostic and Pediatric Sciences, University of Pavia, 27100 Pavia, Italy
2. Unit of Orthodontics and Pediatric Dentistry, Section of Dentistry, Department of Clinical, Surgical, Diagnostic and Pediatric Sciences, University of Pavia, 27100 Pavia, Italy
3. Department of Industrial Chemistry “Toso Montanari”, University of Bologna, 40126 Bologna, Italy
4. Incos-Cosmeceutica Industriale, Funo di Argelato, 40050 Bologna, Italy