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Ítem Creation of a three-dimensional model of the mandible and the TMJ in vivo by means of the finite element method.(Quintessenz Verlags GmbH, 2002-04-01) Castaño MC; Zapata U; Pedroza A; Jaramillo JD; Roldán S; Universidad EAFIT. Departamento de Ingeniería Mecánica; Bioingeniería GIB (CES – EAFIT)The aim of this study was to develop a three-dimensional finite element model of the mandible, including its TMJ. The model consisted of 7942 nodes and 41,010 elements, which were obtained from a convergence test, done to minimize the result error. It included cancellous and cortical bone, periodontal ligament, masticatory muscles (masseters, temporalis, lateral and internal pterygoids), teeth and the articular disk. All characteristics such as dental, mandibular, and muscle geometry were obtained from a computerized tomography (CT) of a living person. CT sections were scanned and digitized with a CAD software program. After images were adequately assembled, a vertical tracing was done which allowed the definition of a three-dimensional mesh. Modeling of teeth was carried out independently and the periodontal ligament was later included, limiting the alveolar area. Muscles were modeled based on flat-scale photographs and total muscle force was distributed in multiple vectors. The articular disk was generated having 2 mm of thickness with the combination of spring-type (axial stiffness) and gap-type (contact) elements. The model was then analyzed with finite element method (FEM) software where a mesh was generated and values for Poisson's ratio, elasticity, and shear modulus were assigned. These were orthotropic for cancellous and cortical bone, and isotropic for dentin, periodontal ligament, articular disk, and temporal bone. The boundary conditions were defined restricting the nodes on the periphery of the temporal bone. It was therefore possible to generate a three-dimensional finite element model based on information obtained in vivo.Ítem Material properties of the skull layers of the primate parietal bone: A single-subject study(Public Library of Science, 2020-01-01) Zapata, U.; Wang, Q.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Bioingeniería GIB (CES – EAFIT)The outer cortical table of the parietal bone has been commonly used as a calvarial bone graft site for the craniofacial reconstruction. However, little is known about how removing the outer table may affect the function and structure of the inner table, and how the knowledge of the biomechanics and material properties of cortical bones will help the calvarial graft to better integrate into the biological and mechanical functions of its surrounding native tissues. In this study, it was hypothesized that there were significant differences in both density and material properties between inner and outer cortical plates in cranial bones. Twelve cylindrical specimens, including inner-outer layers, of cortical parietal bone of a female baboon were collected. Cortical thicknesses and densities were measured, and elastic properties were assessed using an ultrasonic technique. Results demonstrated remarkable difference in both thickness (t = 8.248, p .0.05) and density (t = 4.926, p.0.05) between inner and outer cortical paired samples. Orthotropic characteristics of the cortical plates were detected as well, these findings suggest that there are differences in biomechanical properties between two surfaces of cranial bones at both tissue and organ levels. How these differences are linked to the stress environments of the inner and outer cranial cortical layers awaits further studies. Further study will greatly enhance our ability to address questions derived from both morphological and craniofacial medicine fields about the development and biomechanics of craniofacial skeletons. © 2020 Zapata, Wang.Ítem The Techniques for Overcoming Depression Questionnaire: Mokken Scale Analysis, Reliability, and Concurrent Validity in Depressed Cardiac Patients(SPRINGER/PLENUM PUBLISHERS, 2017-02-01) Freedland, K.E.; Lemos, M.; Doyle, F.; Steinmeyer, B.C.; Csik, I.; Carney, R.M.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Bioingeniería GIB (CES – EAFIT)The Techniques for Overcoming Depression (TOD) questionnaire assesses the frequency with which patients being treated for depression use cognitive-behavioral techniques in daily life. This study examined its latent structure, reliability and concurrent validity in depressed cardiac patients. The TOD was administered at the initial and final treatment sessions in three trials of cognitive behavior therapy (CBT) (n = 260) for depression in cardiac patients. Mokken scaling was used to determine its dimensionality. The TOD is unidimensional in depressed cardiac patients, both at the initial evaluation (H = .46) and the end of treatment (H = .47). It is sensitive to change and the total score correlates with therapist ratings of the patient’s socialization to CBT (r = .40, p < .05), homework adherence (r = .36, p < .05), and use of cognitive-behavioral techniques (r = .51, p < .01). TOD scores were associated with post-treatment depression scores in two of the trials (p < .01 in both analyses). The TOD is a unidimensional, reliable, valid, and clinically informative measure of self-reported use of cognitive-behavioral techniques for overcoming depression in cardiac patients. Studies of the TOD in other depressed patient populations are needed. © 2016, Springer Science+Business Media New York.