1. Dental Materials Laboratory, Academic Area of DentistryAutonomous University of Hidalgo State Circuito Ex Hacienda La Concepción S/N San Agustín Tlaxiaca Hgo 42160 Mexico
2. Department of Restorative Dentistry, School of DentistryFederal University of Pelotas Goncalves Cháves 457 Pelotas RS 96015–560 Brazil
3. Department of Prosthodontics, School of DentistryUniversity of Taubaté Quatro de Março, 432 Taubaté 12020–270 Brazil