1. Department of Restorative Dentistry, Araraquara Dental School, Universidade Estadual Paulista (UNESP), 1680 Humaitá Street, 14801-903 Araraquara, SP, Brazil
2. Departments of Physics & Astronomy and Chemistry, Trent Centre for Biomaterials Research, Trent University, Peterborough, ON, Canada K9J 7B8