1. School of Engineering and Technology, University of Hertfordshire, College Lane, Hatfield, Hertfordshire AL10 9AB, UK
2. The Dental Implant and Gingival-Plastic Surgery Centre, 717 Christchurch Road, Bournemouth, Dorset BH7 6AF, UK
3. CENIMAT/I3N, Materials Science Department, Faculty of Science and Technology, New University of Lisbon, Campus of Caparica, 2829-516 Caparica, Portugal
4. Department of Endodontics, School of Dental Medicine, University of Pennsylvania, 3451 Walnut Street, Philadelphia, PA 19104, USA