1. Department of Endodontics; Federal University of Ceará; Sobral Brazil
2. Departmento of Endodontics; Fortaleza University; Fortaleza Brazil
3. Department of Microbiology; Fortaleza University; Fortaleza Brazil
4. Department of Physics; Federal University of Ceará; Fortaleza Brazil
5. Department of Endodontics; Pernambuco University; Recife Brazil