1. Cancer Institute, University of Mississippi Medical Center, Jackson, MS 39216, USA.
2. Institut National de la Santé et de la Recherche Médicale, U 977; Dental Faculty, University of Strasbourg, 67000 Strasbourg, France.
3. Department of Operative Dentistry and Endodontics, Dental Faculty, University of Strasbourg, 67000 Strasbourg, France.