1. Department of Prosthodontics and Bucco-Facial Surgery, School of Dentistry, Federal University of Pernambuco, Recife, Brazil.
2. Department of Dentistry, UNINASSAU, Caruaru, Brazil.
3. Department of Biomaterials and Oral Biology, School of Dentistry, University of São Paulo, São Paulo, Brazil.
4. Department of Physics, Federal University of Pernambuco - UFPE, Recife, Brazil.