1. Faculty
of Dentistry, McGill University, 3640 University Street, Montreal, Quebec H3A 0C7, Canada
2. Department
of Prosthodontics, Faculty of Dentistry, Sana’a University, Wadi Dhaher Road, Sana’a, Yemen
3. Department
of Physical Chemistry, Complutense University of Madrid, Avenida Séneca,
2, 28040 Madrid, Spain
4. Faculty
of Dentistry of Ribeirão Preto, University of São Paulo, 253 Avenida Prof. Dr. Zeferino Vaz, 109 Vila Monte Alegre, Ribeirão Preto, São Paulo, Brazil