Avaliação tridimensional da sínfise mandibular em crânios secos e sua associação com diferentes classificações de tipos faciais

• Autor(a) principal: Franco, Fernanda Catharino Menezes
• Data de Publicação: 2014
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/14017
• topic: Mentum; Morphology of the face; Cone beam computed tomography; Mento; Morfologia da face; Tomografia computadorizada de feixe cônico; CNPQ::CIENCIAS DA SAUDE::ODONTOLOGIA

The objective of this study was to develop a quantitative and qualitative morphological study of the mandibular symphysis (SM) region through the construction of three-dimensional models (3D) and assess their association with different classifications of facial patterns. Sixty-one human dry skulls of young adults with normal occlusion, aged 18 and 45, with complete dentition, were evaluated. Cone beam computed tomography (CBCT) of all skulls were obtained in a standard manner. The facial pattern was determined by anthropometric and cephalometric methods. By the anthropometric criteria, using as reference the facial index (IF), facial patterns were classified as: euriprosopic (≤ 84.9), mesoprosopic (85.0 to 89.9) and leptoprosopic (≥ 90.0). By the cephalometric criteria, the mandibular plane (FMA) determined the facial pattern as short (≤ 21.0), medium (21.1 to 29.0) and long (≥ 29.1), and the facial height index (IAF) determined the classification of the face in hypodivergent (≥ 0.750), average (0.749 to 0.650) and hyperdivergent (≤ 0.649). Data obtained were reconstructed using ITK-SNAP software. Teeth present in this region, incisors, canines and premolars, were separated from the model by semi-automatic segmentation, followed by manual refinement. Then the 3D models were obtained only with bone tissue, enabling the measurement of bone volume in mm3 (VOL) and radiographic density, by the mean intensity of the voxels (MVox). With the Geomagic Studio 10 software an anatomical best fit superimposition of 3D models was performed to standardly cut in the midline. For each symphysis the height (Alt) and width (Larg) were measured, and the ratio between height and width was calculated (PAL). The evaluation of the presence of alveolar defects was done directly on the mandible, thus obtaining the average of all the alveolar bone height (AltOss) and the average of the size of the present dehiscences (Medef). The intra-class correlation index (ICC) showed values between 0.923 to 0.994, indicating high reproducibility and reliability of the measurements. The differences between the groups as determined by the facial pattern (IF, FMA and LAI) ratings were assessed by analysis of variance (one way ANOVA) followed by post-hoc Tukey test. The degree of association between facial pattern and Vol, MVox, PAL, Alt, Larg, AltOss and Medef variables was assessed by Pearson's correlation coefficient with a t-test for r. The results indicated no difference or association between the volume, density and presence of radiographic alveolar defects of the SM and the facial pattern when determined by IF, FMA and IAF. There was a tendency of a longer SM in individuals with longer faces, but the width was not associated with the facial pattern. These results suggest that the classifications used to determine the facial pattern does not represent the 3D nature of the human face and are not associated with the morphology of the SM.