1 Department of Oral Surgery and Orthopedics, Division of Dental Radiology, Dental School, Federal University of Rio Grande do Sul (UFRGS). Porto Alegre, Rio Grande do Sul, Brazil. heraldo.silveira@ufrgs.br Universidade Federal do Rio Grande do Sul Department of Oral Surgery and Orthopedics, Division of Dental Radiology Dental School Federal University of Rio Grande do Sul (UFRGS) Porto Alegre, Rio Grande do Sul Brazil heraldo.silveira@ufrgs.br.