The Use of Platelet Concentrates in the Reconstruction of the Alveolar Cleft Defect: A Systematic Review and Meta-Analysis.

OBJECTIVE: Evaluate quantitative and qualitative outputs when comparing the incidence of platelet concentrates (PCs) combined with autogenous bone grafts to an autograft control group for the reconstruction of alveolar cleft defects. DESIGN: Systematic review and meta-analysis. PATIENTS/PARTICIPANTS: Randomized and nonrandomized controlled clinical trials where PCs were used in the reconstruction of alveolar cleft defects. INTERVENTIONS: Use of PCs in combination with autogenous bone graft in the experimental group and autogenous bone graft alone in the control group. MAIN OUTCOME MEASURE(S): Average bone formation and bone density were evaluated, mean differences were calculated and pooled by a meta-analysis technique. Additionally, clinical outcomes such as wound dehiscence, closure of the oronasal fistula, pain, swelling, discharges, infections, and bleeding were considered in the qualitative synthesis. RESULTS: After an evaluation of forty-nine articles, nineteen were considered for the review. The qualitative assessment of bone density, bone formation, and clinical outcomes showed no differences between groups in most of the included studies. The meta-analysis showed no statistical differences between PCs groups when compared to the control group in bone density at three months (mean difference 45.67 HU, P = .23) and six months (mean difference 48.57 HU, P = .64). Neither were statistical differences in the percentage of regenerated bone volume at six months (mean difference 6.39%, P = .15) and the volume of newly formed bone at 12 months (mean difference 0.37 mm3, P = .99). CONCLUSIONS: There were no significant differences in terms of bone formation, bone density, and clinical outputs between groups.

Tombstone cost and longevity: The San Pedro Cemetery Museum in Medellín in Colombia.

BACKGROUND: Studies in the West suggest that tombstone cost is associated with longevity. The objective of this observational study was to investigate the association between tombstone cost and longevity in a large cemetery in Latin America. METHODS: Age at death was obtained from 2,273 consecutive death certificates held at the San Pedro Cemetery Museum in Medellín in Colombia. Subjects died in 2022, 2021, or 2020. Tombs are arranged in galleries in the cemetery and tombstone cost was based on the material from which the tombstone was made, its position in the gallery, and its ornamentation. Analysis of variance was used and the assumption of equal variance was not violated. RESULTS: Approximately 77% of tombstones were of low cost, 21% of medium cost, and 2% of high cost. Data from 1,751 subjects were used to investigate differences in longevity according to tombstone cost while adjusting for sex, civil status, violent death, and year of death. Longevity was similar in the low-cost group and medium-cost group: 64.3 years (63.2, 65.3) versus 63.3 years (61.3, 65.3) [estimated mean (95% confidence interval)]. Longevity was lower in the high-cost group: 47.0 years (40.1, 53.9). CONCLUSIONS: The inverse association between tombstone cost and longevity would suggest that people in Medellín are inclined to spend more on tombstones when commemorating the tragic death of a young person.

Biomechanical in silico evaluation of a 3D novel total hip implant with cemented fixation using finite elements.

This paper presents the biomechanical evaluation of a proposed replacement implant for a total hip arthroplasty considering both the effect of the material and using a numerical tool. The use of titanium, alumina, polycarbonate urethane (PCU), and nitride titanium allows the manufacture of a cemented hip prosthesis with better resistance to corrosion, greater biocompatibility, greater mechanical resistance for physiological conditions, and does not present plastic deformation. This article provides an analysis of biomaterials and adequate geometries for a total hip prosthesis, with the aim of finding the optimal model, thus avoiding complications such as loosening or fatigue that current models present. Ultimately, the proposed design of the prosthesis was modeled using finite elements, simulating the static loads to which the prosthesis is subjected and evaluating the chosen biomaterials. Clinical Relevance - Osteoarthritis is a degenerative disease that affects 20% of the population above 60 years of age, particularly the hip joint, which is why, in most cases, a total arthroplasty of the expressed joint is required. In this procedure, the hip is replaced with an implant, which failure is usually related with either geometrical conditions or selected materials. An exponential increase of 136% in the incidence of total hip arthroplasty is expected by 2030.

Development of an Intervertebral Disc for Cervical Spondylosis Composed of Seeded Biomaterials.

Most of the current artificial disc prosthesis presented a restricted range of motion. Here we propose the design of a novel intervertebral disc composed of carbon fiber, hyaluronic methylcellulose hydrogel loaded with mesenchymal stem cells and polycaprolactone. The prosthesis was biomechanically evaluated under two static physiological conditions to study the mechanical influence of the material on the device. The results obtained in the simulations showed a not only a congruent behavior with preclinical condition, but also that the proposed materials met the desired biomechanical properties Clinical Relevance- Cervical spondylosis is a degenerative disease of the human spine that causes wear and tear of the cervical intervertebral discs. Nowadays, the proposed surgical solutions do not allow fully recovery of normal movement because the surgical intervention do not emulate the natural range of motion, may lack shock absorption mechanisms, show signs of fatigue over time affecting its durability, and do not have good bone adhesion. Therefore, hypermobility and problems of heterotopic ossification may restrict the range of motion.

Material properties of the skull layers of the primate parietal bone: A single-subject study.

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.

Biomechanics of the canine mandible during bone transport distraction osteogenesis.

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.

Bone regeneration and docking site healing after bone transport distraction osteogenesis in the canine mandible.

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.

The role of the sutures in biomechanical dynamic simulation of a macaque cranial finite element model: implications for the evolution of craniofacial form.

The global biomechanical impact of cranial sutures on the face and cranium during dynamic conditions is not well understood. It is hypothesized that sutures act as energy absorbers protecting skulls subjected to dynamic loads. This hypothesis predicts that sutures have a significant impact on global patterns of strain and cranial structural stiffness when analyzed using dynamic simulations; and that this global impact is influenced by suture material properties. In a finite element model developed from a juvenile Rhesus macaque cranium, five different sets of suture material properties for the zygomaticotemporal sutures were tested. The static and dynamic analyses produced similar results in terms of strain patterns and reaction forces, indicating that the zygomaticotemporal sutures have limited impact on global skull mechanics regardless of loading design. Contrary to the functional hypothesis tested in this study, the zygomaticotemporal sutures did not absorb significant amounts of energy during dynamic simulations regardless of loading speed. It is alternatively hypothesized that sutures are mechanically significant only insofar as they are weak points on the cranium that must be shielded from unduly high stresses so as not to disrupt vitally important growth processes. Thus, sutural and overall cranial form in some vertebrates may be optimized to minimize or otherwise modulate sutural stress and strain.

Architecture and microstructure of cortical bone in reconstructed canine mandibles after bone transport distraction osteogenesis.

Reconstruction of the canine mandible using bone transport distraction osteogenesis has been shown to be a suitable method for correcting segmental bone defects produced by cancer, gunshots, and trauma. Although the mechanical quality of the new regenerate cortical bone seems to be related to the mineralization process, several questions regarding the microstructural patterns of the new bony tissue remain unanswered. The purpose of this study was to quantify any microstructural differences that may exist between the regenerate and control cortical bone. Five adult American foxhound dogs underwent unilateral bone transport distraction of the mandible to repair bone defects of 30-35 mm. Animals were killed 12 weeks after the beginning of the consolidation period. Fourteen cylindrical cortical samples were extracted from the superior, medial, and inferior aspects of the lingual and buccal plates of the reconstructed aspect of the mandible, and 21 specimens were collected similarly from the contralateral aspect of the mandible. Specimens were evaluated using histomorphometric and micro-computed tomographic techniques to compare their microstructure. Except for differences in haversian canal area, histomorphometric analyses suggested no statistical differences in microstructure between regenerate and control cortical bone. Morphological evaluation suggested a consistent level of anisotropy, possibly related to the distraction vector. After 12 weeks' consolidation, bone created during bone transport distraction osteogenesis was comparable to native bone in microstructure, architecture, and mechanical properties. It is proposed that, after enough time, the properties of the regenerate bone will be identical to that of native bone.

Biomechanical characteristics of regenerated cortical bone in the canine mandible.

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 (E(1) and E(2) ) 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.

Three-dimensional evaluation of mandibular bone regenerated by bone transport distraction osteogenesis.

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.

The global impact of sutures assessed in a finite element model of a macaque cranium.

The biomechanical significance of cranial sutures in primates is an open question because their global impact is unclear, and their material properties are difficult to measure. In this study, eight suture-bone functional units representing eight facial sutures were created in a finite element model of a monkey cranium. All the sutures were assumed to have identical isotropic linear elastic material behavior that varied in different modeling experiments, representing either fused or unfused sutures. The values of elastic moduli employed in these trials ranged over several orders of magnitude. Each model was evaluated under incisor, premolar, and molar biting conditions. Results demonstrate that skulls with unfused sutures permitted more deformations and experienced higher total strain energy. However, strain patterns remained relatively unaffected away from the suture sites, and bite reaction force was likewise barely affected. These findings suggest that suture elasticity does not substantially alter load paths through the macaque skull or its underlying rigid body kinematics. An implication is that, for the purposes of finite element analysis, omitting or fusing sutures is a reasonable modeling approximation for skulls with small suture volume fraction if the research objective is to observe general patterns of craniofacial biomechanics under static loading conditions. The manner in which suture morphology and ossification affect the mechanical integrity of skulls and their ontogeny and evolution awaits further investigation, and their viscoelastic properties call for dynamic simulations.

Biomechanical configurations of mandibular transport distraction osteogenesis devices.

Mandibular bone transport (MBT) distraction osteogenesis devices are used for achieving reconstruction of mandibular defects in a predictable way, with few complications, less complexity than other alternative surgical procedures, and minimal tissue morbidity. However, selection of appropriate MBT device characteristics is critical for ensuring both their mechanical soundness and their optimal distraction function for each patient's condition. This article assesses six characteristics of currently available MBT devices to characterize their design and function and to classify them in a way that assists the selection of the best device option for each clinical case. In addition, the present work provides a framework for both the biomechanical conception of new devices and the modification of existing ones.

Material properties of mandibular cortical bone in the American alligator, Alligator mississippiensis.

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.

Ejecución de un sistema piloto de tele-radiología en Medellín, Colombia / Implementing a teleradiology pilot system in Medellín, Colombia

Objetivo: Aplicar un sistema piloto de tele-radiología en la ciudad de Medellín con software de acceso remoto que permita la comunicación e interpretación a distancia de imágenes biomédicas. Materiales y métodos: Se utilizaron imágenes de estudios de resonancia magnética y tomografía computadorizada almacenados en formato DICOM. Los datos se transmitieron en una red punto a punto mediante líneas de red digital de servicios integrados (RDSI) entre dos centros de diagnóstico radiológico. El sistema se llevó a cabo bajo arquitectura PC basada en Intel x86 con sistema operativo Windows® 2000. Resultados: Para la lectura y visualización local de imágenes almacenadas en formato DICOM, se desarrolló una aplicación en Java con funciones que permiten su manipulación y la opción de exportar a otros formatos como JPEG, TIFF y BMP. Conclusiones: El sistema permitió en modalidades como tomografía computadorizada (TC) e imagen por resonancia magnética (RM) un diagnóstico e interpretación remota clínicamente confiables, con tiempos de respuesta aceptables para las necesidades y modo de actuar reales de los centros radiológicos participantes.

Objective: To implement a teleradiology pilot system in Medellín city using software for remote access, this allows the communication and interpretation of biomedical images at distance. Materials and methods: Images from different magnetic resonance and computed tomography studies stored in DICOM format were used. Data were transmitted in a point-to-point network using an integrated services digital network (ISDN) line between two radiological diagnostic centers. The system was developed under PC Intel’s x86 architecture, with Windows® 2000 as the operating system. Results: In order to read and visualize images stored in DICOM format, a Java application with functions that allow their manipulation and the option to export them to other formats such as JPEG, TIFF and BMP was developed. Conclusion: The system allows a clinically reliable diagnostic and remote interpretation for modalities such as computed tomography (CT) and magnetic resonance (MR) images, with acceptable response times.

Reconstrucción tridimensional de estructuras óseas a partir de estudios tomográficos para su manipulación en modelos de elementos finitos / Three dimensional reconstruction of osseous structures based on tomographic studies for the manipulation of finite element models

La reconstrucción y visualización tridimensional de estructuras óseas es una herramienta útil para el diagnóstico clínico a partir de imágenes médicas. Además, la aplicación de diferentes técnicas de ingeniería, como el diseño asistido por computador y modelaciones numéricas de dichas estructuras, brindan un apoyo significativo a los profesionales e investigadores del área de la salud para la realización de procedimientos clínicos más acertados. Este artículo presenta un método de reconstrucción tridimensional de estructuras óseas a partir de imágenes topográficas planas en formato DICOM, que consta de un módulo de procesamientos de las imágenes MATLAB 6.5 y un módulo de reconstrucción, manipulación y visualización de estructuras sólidas en el software CAD/CAM ProENGINEER WILDFIRE para su posterior utilización en software de electos finitos...

Evaluación del comportamiento mecánico de pernos fabricados con materiales diferentes / Evaluation of mechanical behavior of prefabricated posts with different materials

En la última década se han realizado esfuerzos para mejorar las propiedades mecánicas de los pernos: La diferencia en el comportamiento mecánico entre el material del perno y la dentina es un parámetro crítico para la transmisión de los esfuerzos ocasionados por las cargas funcionales. El objetivo del presente estudio fue evaluar la distribución de las fuerzas a través de la dentina de dientes restaurados con pernos prefabricados en tres materiales diferentes utilizando el método de los elementos finitos con el fin de identificar aquel que presentara un mejor comportamiento desde el punto de vista de esfuerzos y deformaciones, lo que incide en la adecuada respuesta mecánica del sistema de pernos. En este estudio se realizó un modelo numérico tridimensional de un canino inferior con sus estructuras de soporte. El modelo es homogéneo, elástico lineal e isotrópico para todos los materiales (cerámica, metales, resinas, dentina, gutapercha y ligamento periodontal) excepto el hueso cortical y esponjoso que fueron considerados ortotrópicos; el perno de fibra de vidrio y de carbono que fueron considerados como transversales isotrópicos. Se elaboraron 3 modelos, cada uno con un perno prefabricado en diferentes materiales (fibra de vidrio, fibra de carbono y titanio), a los que se aplicaron cargas verticales y oblicuas para evaluar los esfuerzos en las siguientes interfaces: Hueso cortical-ligamento periodontal, ligamento periodontal-raíz (dentina), raíz- cemento-perno tanto para el aspecto bucal (labial) como para el lingual de cada uno de los modelos obtenidos…

Comportamiento de las fuerzas generadas por un perno colado sobre una raíz por medio de un análisis tridimensional de elementos finitos / Behavior of forces generated by a cast post on the root by means of a three dimensional finite element analysis

El propósito de este estudio fue desarrollar un modelo tridimensional de elementos finitos, de un canino inferior restaurado con un perno colado y una corona completa metal-cerámica para evaluar la distribución de esfuerzos sobre la dentina radicular. El modelo incluyó hueso esponjoso, hueso cortical y ligamento periodontal. Sobre el canino modelado se aplicaron fuerzas de 116 newtons en sentido vertical y oblicuo, en tres alturas óseas diferentes y tres longitudes de perno. Los esfuerzos críticos se presentaron en la superficie lingual de la raíz en la región cervical. Cuando la carga fue aplicada en sentido vertical no se encontró diferencias en la distribución de los esfuerzos compresivos al variar la longitud del perno con cada una de las alturas óseas; pero a medida que se disminuyó la altura ósea, la concentración del esfuerzo compresivo fue mayor en la región cerca de la cresta ósea al aplicar la carga oblicua los esfuerzos compresivos en la raíz y en el perno fueron importantes cuando la longitud del hueso disminuyó. En conclusión se encontró que la perdida ósea es más importante que la longitud del perno en el comportamiento biomecánico de la restauración, lo cual demuestra la importancia del efecto de férula que el hueso ofrece. Además, la carga vertical es bien tolerada por el complejo dento-alveolar en comparación con las cargas oblicuas, ya que ocurre una distribución uniforme del esfuerzo producido por dicha carga...