1. Department of Oral Pathology, School of Dentistry Federal University of Rio Grande do Sul Porto Alegre Rio Grande do Sul Brazil
2. Department of Oral Diagnosis, Piracicaba Dental School University of Campinas Piracicaba Brazil
3. Laboratory of Epithelial Biology, Department of Periodontics and Oral Medicine University of Michigan School of Dentistry Ann Arbor Michigan USA
4. Department of Oral Medicine, Hospital de Clínicas de Porto Alegre (HCPA/UFRGS) Federal University of Rio Grande do Sul Porto Alegre Rio Grande do Sul Brazil
5. Laboratory of Tissue Culture, Department of Basic and Oral Biology University of Sao Paulo School of Dentistry Ribeirao Preto Rio Grande do Sul Brazil
6. São Carlos Institute of Physics University of São Paulo (USP) São Carlos São Paulo Brazil