1. Department of Restorative Dentistry and Dental Materials, University of Siena, Italy;
2. Department of Dental Sciences, University of Bologna, Italy;
3. Department of Oral Biology and Maxillofacial Pathology, School of Dentistry, Medical College of Georgia, Augusta, USA; and
4. Pediatric Dentistry and Orthodontics, Faculty of Dentistry, Prince Philip Dental Hospital, University of Hong Kong, 34 Hospital Road, Pokfulam, Hong Kong, SAR, China;