1. University of Milan; Department of Biomedical, Surgical and Dental Sciences; Via Beldiletto 1/3 Milan Italy 20142
2. University of Parma; Polo Clinico di Odontostomatologia, SBiBiT Department; Via Gramsci, 14 Parma Italy 43100
3. University College of London; Eastman Dental Institute; 256 Gray's Inn Road London UK WC1X 8LD
4. Sheffield Children's NHS Foundation Trust; Department of Dermatology, Sheffield Children's Hospital; Sheffield UK S10 2JF
5. University of Newcastle upon Tyne; Department of Oral Medicine, School of Dental Sciences; Framlington Place Newcastle upon Tyne UK NE2 4BW