Repositorio Institucional Universidad EAFIT ::Examinando por Materia "mandible"

Examinando por Materia "mandible"

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Biomechanical characteristics of regenerated cortical bone in the canine mandible
(WILEY-BLACKWELL, 2011-07-01) Zapata, Uriel; Opperman, Lynne A.; Kontogiorgos, Elias; Elsalanty, Mohammed E.; Dechow, Paul C.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Bioingeniería GIB (CES – EAFIT)
To test the mechanical properties of regenerate cortical bone created using mandibular bone transport (MBT) distraction, five adult male American foxhound dogs underwent unilateral distraction of the mandible with a novel MBT device placed to linearly repair a 30-35 mm bone defect. The animals were sacrificed 12 weeks after the beginning of the consolidation period. Fourteen cylindrical specimens were taken from the inner (lingual) and outer (buccal) plates of the reconstructed mandible and 21 control specimens were removed from the contralateral aspect of the mandible. The mechanical properties of the 35 cylindrical cortical bone specimens were assessed by using a non-destructive pulse ultrasound technique. Results showed that all of the cortical mechanical properties exhibit higher numerical values on the control side than the MBT regenerate side. In addition, both densities and the elastic moduli in the direction of maximum stiffness of the regenerate cortical bone specimens are higher on the lingual side than the buccal side. Interestingly, there is no statistical difference between elastic modulus (E1 and E2) in orthogonal directions throughout the 35 cortical specimens. The data suggest that not only is the regenerate canine cortical bone heterogeneous, but the elastic mechanical properties tend to approximate transverse isotropy at a tissue level, as opposed to control cortical bone, which is orthotropic. In addition, the elastic mechanical properties are higher not only on the control side but also in the lingual anatomical position, suggesting a stress shielding effect from the presence of the reconstruction plate. © 2011 John Wiley & Sons, Ltd.
Biomechanics of the canine mandible during bone transport distraction osteogenesis
(ASME, 2014-11-01) Zapata, Uriel; Dechow, Paul C.; Watanabe, Ikuya; Elsalanty, Mohammed E.; Opperman, Lynne A.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Bioingeniería GIB (CES – EAFIT)
This study compared biomechanical patterns between finite element models (FEMs) and a fresh dog mandible tested under molar and incisal physiological loads in order to clarify the effect of the bone transport distraction osteogenesis (BTDO) surgical process. Three FEMs of dog mandibles were built in order to evaluate the effects of BTDO. The first model evaluated the mandibular response under two physiological loads resembling bite processes. In the second model, a 5.0 cm bone defect was bridged with a bone transport reconstruction plate (BTRP). In the third model, new regenerated bony tissue was incorporated within the defect to mimic the surgical process without the presence of the device. Complementarily, a mandible of a male American foxhound dog was mechanically tested in the laboratory both in the presence and absence of a BTRP, and mechanical responses were measured by attaching rosettes to the bone surface of the mandible to validate the FEM predictions. The relationship between real and predicted values indicates that the stress patterns calculated using FEM are a valid predictor of the biomechanics of the BTDO procedures. The present study provides an interesting correlation between the stiffness of the device and the biomechanical response of the mandible affected for bone transport. Copyright © 2014 by ASME.
Biomechanics of the canine mandible during bone transport distraction osteogenesis
(ASME, 2014-11-01) Zapata, Uriel; Dechow, Paul C.; Watanabe, Ikuya; Elsalanty, Mohammed E.; Opperman, Lynne A.; Zapata, Uriel; Dechow, Paul C.; Watanabe, Ikuya; Elsalanty, Mohammed E.; Opperman, Lynne A.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de Ingeniería
This study compared biomechanical patterns between finite element models (FEMs) and a fresh dog mandible tested under molar and incisal physiological loads in order to clarify the effect of the bone transport distraction osteogenesis (BTDO) surgical process. Three FEMs of dog mandibles were built in order to evaluate the effects of BTDO. The first model evaluated the mandibular response under two physiological loads resembling bite processes. In the second model, a 5.0 cm bone defect was bridged with a bone transport reconstruction plate (BTRP). In the third model, new regenerated bony tissue was incorporated within the defect to mimic the surgical process without the presence of the device. Complementarily, a mandible of a male American foxhound dog was mechanically tested in the laboratory both in the presence and absence of a BTRP, and mechanical responses were measured by attaching rosettes to the bone surface of the mandible to validate the FEM predictions. The relationship between real and predicted values indicates that the stress patterns calculated using FEM are a valid predictor of the biomechanics of the BTDO procedures. The present study provides an interesting correlation between the stiffness of the device and the biomechanical response of the mandible affected for bone transport. Copyright © 2014 by ASME.
Bone regeneration and docking site healing after bone transport distraction osteogenesis in the canine mandible
(W.B. Saunders Ltd, 2012-01-01) Nagashima, L.K.; Rondon-Newby, M.; Zakhary, I.E.; Nagy, W.W.; Zapata, U.; Dechow, P.C.; Opperman, L.A.; Elsalanty, M.E.; Nagashima, L.K.; Rondon-Newby, M.; Zakhary, I.E.; Nagy, W.W.; Zapata, U.; Dechow, P.C.; Opperman, L.A.; Elsalanty, M.E.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de Ingeniería
Purpose: Bone transport distraction osteogenesis provides a promising alternative to traditional grafting techniques. However, existing bone transport distraction osteogenesis devices have many limitations. The purpose of this research was to test a new device, the mandibular bone transport reconstruction plate, in an animal model with comparable mandible size to humans and to histologically and mechanically examine the regenerate bone. Materials and Methods: Eleven adult foxhounds were divided into an unreconstructed control group of 5 animals and an experimental group of 6 animals. In each animal, a 34-mm segmental defect was created in the mandible. The defect was reconstructed with a bone transport reconstruction plate. Histologic and biomechanical characteristics of the regenerate and unrepaired defect were analyzed and compared with bone on the contralateral side of the mandible after 4 weeks of consolidation. Results: The reconstructed defect was bridged with new bone, with little bone in the control defect. Regenerate density and microhardness were 22.3% and 42.6%, respectively, lower than the contralateral normal bone. Likewise, the anisotropy of the experimental group was statistically lower than in the contralateral bone. Half the experimental animals showed nonunion at the docking site. Conclusion: The device was very stable and easy to install and activate. After 1 month of consolidation, the defect was bridged with new bone, with evidence of active bone formation. Regenerate bone was less mature than the control bone. Studies are underway to identify when the regenerate properties compare with normal bone and to identify methods to augment bone union at the docking site. © 2012 American Association of Oral and Maxillofacial Surgeons.
Bone regeneration and docking site healing after bone transport distraction osteogenesis in the canine mandible
(W.B. Saunders Ltd, 2012-01-01) Nagashima, L.K.; Rondon-Newby, M.; Zakhary, I.E.; Nagy, W.W.; Zapata, U.; Dechow, P.C.; Opperman, L.A.; Elsalanty, M.E.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Bioingeniería GIB (CES – EAFIT)
Purpose: Bone transport distraction osteogenesis provides a promising alternative to traditional grafting techniques. However, existing bone transport distraction osteogenesis devices have many limitations. The purpose of this research was to test a new device, the mandibular bone transport reconstruction plate, in an animal model with comparable mandible size to humans and to histologically and mechanically examine the regenerate bone. Materials and Methods: Eleven adult foxhounds were divided into an unreconstructed control group of 5 animals and an experimental group of 6 animals. In each animal, a 34-mm segmental defect was created in the mandible. The defect was reconstructed with a bone transport reconstruction plate. Histologic and biomechanical characteristics of the regenerate and unrepaired defect were analyzed and compared with bone on the contralateral side of the mandible after 4 weeks of consolidation. Results: The reconstructed defect was bridged with new bone, with little bone in the control defect. Regenerate density and microhardness were 22.3% and 42.6%, respectively, lower than the contralateral normal bone. Likewise, the anisotropy of the experimental group was statistically lower than in the contralateral bone. Half the experimental animals showed nonunion at the docking site. Conclusion: The device was very stable and easy to install and activate. After 1 month of consolidation, the defect was bridged with new bone, with evidence of active bone formation. Regenerate bone was less mature than the control bone. Studies are underway to identify when the regenerate properties compare with normal bone and to identify methods to augment bone union at the docking site. © 2012 American Association of Oral and Maxillofacial Surgeons.
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.
Evaluation of the structural behavior of three and four implant-supported fixed prosthetic restorations by finite element analysis.
(ELSEVIER IRELAND LTD, 2012-04-01) Correa S; Ivancik J; Isaza JF; Naranjo M; Universidad EAFIT. Departamento de Ingeniería de Diseño; Ingeniería de Diseño (GRID)
PURPOSE: There is much controversy about the minimum number of implants and maximum cantilever length in mandible prosthetic restoration. Finite elements analysis of three and four implant-supported prostheses was performed to determine the stresses in the superstructure, implants and cortical bone and, therefore, the failure prediction for each restoration. METHODS: An edentulous mandible was modeled from CT scan images. Two finite element models of three and four implant-supported prostheses with cantilever lengths of 10 and 15 mm were created. Occlusal loads in different parts of the superstructure were applied and shear and normal stresses were calculated. RESULTS: Two failure criteria were analyzed: the von Mises criterion for isotropic materials (superstructure and implants) and the Tsai-Wu criterion for transversely isotropic material (cortical bone). Both criteria predict failure in the three implant-supported prosthesis for all cases analyzed. The same applies for the four-implant prosthesis of 15 mm cantilever length. However, four implants and a cantilever length of 10mm passed the failure criteria and were considered safe. CONCLUSIONS: The results from the patient analyzed showed that fixed support prostheses on three implants are not recommended from a structural point of view because they do not adequately support occlusal loads. Excessive stress in the superstructure and the cortical bone can be expected, which would anticipate the failure of the restoration. Fixed support prostheses on four implants with a cantilever length of 10mm properly resist occlusal loading.
Evaluation of the structural behavior of three and four implant-supported fixed prosthetic restorations by finite element analysis.
(ELSEVIER IRELAND LTD, 2012-04-01) Correa S; Ivancik J; Isaza JF; Naranjo M; Universidad EAFIT. Departamento de Ingeniería Mecánica; Bioingeniería GIB (CES – EAFIT)
PURPOSE: There is much controversy about the minimum number of implants and maximum cantilever length in mandible prosthetic restoration. Finite elements analysis of three and four implant-supported prostheses was performed to determine the stresses in the superstructure, implants and cortical bone and, therefore, the failure prediction for each restoration. METHODS: An edentulous mandible was modeled from CT scan images. Two finite element models of three and four implant-supported prostheses with cantilever lengths of 10 and 15 mm were created. Occlusal loads in different parts of the superstructure were applied and shear and normal stresses were calculated. RESULTS: Two failure criteria were analyzed: the von Mises criterion for isotropic materials (superstructure and implants) and the Tsai-Wu criterion for transversely isotropic material (cortical bone). Both criteria predict failure in the three implant-supported prosthesis for all cases analyzed. The same applies for the four-implant prosthesis of 15 mm cantilever length. However, four implants and a cantilever length of 10mm passed the failure criteria and were considered safe. CONCLUSIONS: The results from the patient analyzed showed that fixed support prostheses on three implants are not recommended from a structural point of view because they do not adequately support occlusal loads. Excessive stress in the superstructure and the cortical bone can be expected, which would anticipate the failure of the restoration. Fixed support prostheses on four implants with a cantilever length of 10mm properly resist occlusal loading.
Material properties of mandibular cortical bone in the American alligator, Alligator mississippiensis
(ELSEVIER SCIENCE INC, 2010-03-01) Zapata, Uriel; Metzger, Keith; Wang, Qian; Elsey, Ruth M.; Ross, Callum F.; Dechow, Paul C.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Bioingeniería GIB (CES – EAFIT)
This study reports the elastic material properties of cortical bone in the mandible of juvenile Alligator mississippiensis obtained by using an ultrasonic wave technique. The elastic modulus, the shear modulus, and Poisson's ratio were measured on 42 cylindrical Alligator bone specimens obtained from the lingual and facial surfaces of 4 fresh Alligator mandibles. The data suggest that the elastic properties of alligator mandibular cortical bone are similar to those found in mammals and are orthotropic. The properties most resemble those found in the cortex of mammalian postcranial long bones where the bone is most stiff in one direction and much less stiff in the two remaining orthogonal directions. This is different from cortical bone found in the mandibles of humans and some monkeys, where the bone has greatest stiffness in one direction, much less stiffness in another direction, and an intermediate amount in the third orthogonal direction. This difference suggests a relationship between levels of orthotropy and bending stress. The comparability of these elastic moduli to those of other vertebrates suggest that the high bone strain magnitudes recorded from the alligator mandible in vivo are not attributable to a lower stiffness of alligator mandibular bone. © 2009 Elsevier Inc.
Three-dimensional evaluation of mandibular bone regenerated by bone transport distraction osteogenesis
(SPRINGER, 2011-07-01) Kontogiorgos, E.; Elsalanty, M.E.; Zapata, U.; Zakhary, I.; Nagy, W.W.; Dechow, P.C.; Opperman, L.A.; Kontogiorgos, E.; Elsalanty, M.E.; Zapata, U.; Zakhary, I.; Nagy, W.W.; Dechow, P.C.; Opperman, L.A.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de Ingeniería
The purpose of this study was to evaluate the structure and material properties of native mandibular bone and those of early regenerate bone, produced by bone transport distraction osteogenesis. Ten adult foxhounds were divided into two groups of five animals each. In all animals, a 3- to 4-cm defect was created on one side of the mandible. A bone transport reconstruction plate, consisting of a reconstruction plate with an attached intraoral transport unit, was utilized to stabilize the mandible and regenerate bone at a rate of 1 mm/day. After the distraction period was finished, the animals were killed at 6 and 12 weeks of consolidation. Micro-computed tomography was used to assess the morphometric and structural indices of regenerate bone and matching bone from the unoperated contralateral side. Significant new bone was formed within the defect in the 6- and 12-week groups. Significant differences (P = 0.05) between mandibular regenerated and native bone were found in regard to bone volume fraction, mineral density, bone surface ratio, trabecular thickness, trabecular separation, and connectivity density, which increased from 12 to 18 weeks of consolidation. We showed that regenerated bone is still mineralizing and that native bone appears denser because of a thick outer layer of cortical bone that is not yet formed in the regenerate. However, the regenerate showed a significantly higher number of thicker trabeculae. © 2011 Springer Science+Business Media, LLC.
Three-dimensional evaluation of mandibular bone regenerated by bone transport distraction osteogenesis
(SPRINGER, 2011-07-01) Kontogiorgos, E.; Elsalanty, M.E.; Zapata, U.; Zakhary, I.; Nagy, W.W.; Dechow, P.C.; Opperman, L.A.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Bioingeniería GIB (CES – EAFIT)
The purpose of this study was to evaluate the structure and material properties of native mandibular bone and those of early regenerate bone, produced by bone transport distraction osteogenesis. Ten adult foxhounds were divided into two groups of five animals each. In all animals, a 3- to 4-cm defect was created on one side of the mandible. A bone transport reconstruction plate, consisting of a reconstruction plate with an attached intraoral transport unit, was utilized to stabilize the mandible and regenerate bone at a rate of 1 mm/day. After the distraction period was finished, the animals were killed at 6 and 12 weeks of consolidation. Micro-computed tomography was used to assess the morphometric and structural indices of regenerate bone and matching bone from the unoperated contralateral side. Significant new bone was formed within the defect in the 6- and 12-week groups. Significant differences (P = 0.05) between mandibular regenerated and native bone were found in regard to bone volume fraction, mineral density, bone surface ratio, trabecular thickness, trabecular separation, and connectivity density, which increased from 12 to 18 weeks of consolidation. We showed that regenerated bone is still mineralizing and that native bone appears denser because of a thick outer layer of cortical bone that is not yet formed in the regenerate. However, the regenerate showed a significantly higher number of thicker trabeculae. © 2011 Springer Science+Business Media, LLC.

Examinando por Materia "mandible"

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