1. Department of Dental Sciences, Faculty of Medicine, University of Liège, Liège, Belgium.
2. Experimental Morphology Unit, Université Catholique de Louvain (UCL), Brussels, Belgium.
3. Laboratoire de Spectroscopie Moléculaire de Surface (LASMOS), University of Namur Namur, Belgium.
4. Department of Odonto-Stomatological Science, Faculty of Medicine and Dentistry, “Sapienza” University of Rome, Italy.