1. Centre for Oral Bioengineering, Faculty of Medicine and Dentistry, Queen Mary University of London, Turner Street, London E1 2AD, UK
2. Division of Dentistry, School of Medical Sciences, The University of Manchester, Manchester M13 9PL, UK
3. Biomedical Sciences Department, Dental Technology Division, University of West Attica, Agiou Spyridonos Street, 122 43 Athens, Greece