Utilização do Cone Beam CT como método tridimensional de análise de marcas dentárias

Abstract

Background: The methods of registration and analysis of bite marks have evolved through the technological advances. Nowadays, the evolution of those methods it’s a priority. The three-dimensional analysis of forensic evidence has become a highlighted procedure when compared to the traditional methods. This three-dimensional analysis is based on the registration of the surface of the bitten object. Objectives: The authors propose the study of the surface and interior of bitten objects by cone beam computerized tomography, which is used in dental practice. We will study the possibility to apply cone beam computerized tomography to the three-dimensional analysis of bite marks in foodstuffs, which may be found in a forensic case scenario. Material and Methods: There were used 8 different types of foodstuffs: chocolate, cheese, apple, chewing gum, pizza, tart (flaky pastry and custard), banana and strawberry. The food was bitten and dental casts of the hypothetical suspects were made. Three-dimensional images of the dental casts and bitten objects were obtained using an x-ray source and the cone beam computerized tomography equipment iCAT® (Imaging Sciences International, Pennsylvania, EUA). The software InVivo5® (Anatomage Inc, EUA) was used to visualize the images, measure its radiopacity in Hounsfield Units (HU) and to do the analysis of the bitemarks in the tomographic cuts and three-dimensional reconstructions. For the superimposition of the three-dimensional reconstructions of the foodstuffs and dental casts, the softwares InVivo5® and 3D Studio Max® were used. Results: There were obtained DICOM images in axial, coronal and sagital cuts from all the material in study. For each type of food a set of HU values was obtained, which varied between – 981 HU and +136 HU. The chocolate had the highest median radiopacity and pizza had the lowest. In all the foodstuffs the bitemark’s contours could be identified and the metric analysis could be made. Individual characteristics such as the shape of the arch were able to be distinguished. The analysis was improved with the three-dimensional reconstruction of the bitemarks and the dental casts. The latter were successfully superimposed as a mean of direct comparison, allowing the identification of the bitters. Conclusion: Cone beam computerized tomography is an accurate, scientific and reproducible mean for bite mark analysis. It showed to have the potential to be a valuable tool for bitemark analysis, and therefore, to the scientific forensic community.