Rendimiento Biomecánico de las Placas de Tibia Proximal Utilizadas en Fracturas de Platillos Tibiales evaluado a través de Modelos de Elementos Finitos: Protocolo de Revisión Sistemática / A systematic Review Protocol Examining the Biomechanical Performance of Proximal Tibial Plates used in Tibial Plate Fractures assessed by Finite Element Analysis

Objetivo. Analizar el rendimiento biomecánico de las placas de tibia proximal utilizadas en fracturas de platillos tibiales evaluado a través de modelos de elementos finitos. Métodos. Se realizará una búsqueda exhaustiva en PubMed/Medline, Embase, Lilacs, Web of Science y Google Scholar. No se utilizará ninguna restricción de idioma o estado de publicación. Dos revisores examinarán de forma independiente los posibles artículos elegibles, de acuerdo con los criterios de selección predefinidos. Se incluirán los estudios que evalúen el rendimiento de los platillos tibiales proximales utilizados en las fracturas del platillo tibial evaluadas mediante el análisis de elementos finitos. La extracción de datos sobre las características del estudio, los métodos, los resultados y la evaluación del riesgo de sesgo se realizará mediante un formulario estandarizado. Considerando el diseño de estudio no se requiere evaluación por comité de ética. Los resultados de esta revisión se difundirán a través de la publicación en revistas revisadas por pares, redes sociales y congresos de la especialidad. Se espera que los resultados de esta revisión permitan optimizar los resultados del manejo quirúrgico de las fracturas de platillos tibiales. Número de registro PROSPERO: CRD42023396015.

Objetive. To analyze the biomechanical performance of proximal tibial plates used in tibial plate fractures evaluated through finite element modeling. Methods. A comprehensive search will be conducted in PubMed/Medline, Embase, Lilacs, Web of Science, and Google Scholar. No language or publication status restrictions will be used. Two reviewers will independently review potential eligible articles according to predefined selection criteria. Studies evaluating the performance of proximal tibial splints used in tibial splint fractures assessed by finite element analysis will be included. Data extraction on study characteristics, methods, results, and risk of bias assessment will be performed using a standardized form. Considering the study design, evaluation by an ethics committee is not required. The results of this review will be disseminated through publication in peer-reviewed journals, social networks and specialty congresses. It is expected that the results of this review will allow optimizing the results of the surgical management of tibial plate fractures. PROSPERO registration number: CRD42023396015.

Substitution for / 中国医学科学杂志(英文版)

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Biomechanical analysis of micro-implants lingual straight wire appliance during retracting maxillary anterior teeth / Análisis biomecánico de microimplantes con dispositivo de alambre recto lingual durante la retracción de dientes maxilares anteriores

This study aimed to establish three-dimensional finite element models of micro-implants-lingual straight wire appliance and to investigate the effects of different wire patterns on the initial displacement of the maxillary anterior teeth and the stress of the periodontal ligament and tooth root during retracting maxillary anterior teeth in lingual orthodontics. A three-dimensional geometric models of maxilla with maxillary dentition was established using Cone-beam CT scan .Three types of maxilla models including microimplants and Duet-Slot Lingual Bracket appliance with three different arch wires ( model A: 0.016 inch × 0.022 inch stainless steel square wire; modelB: 0.016 inch stainless steel round wire; model C: double wire of 0.016 inch × 0.022 inch stainless steel square wire + anterior teeth 0.016 inch stainless steel round wire) were assembled by Unigraphics NX 8.5 software. The labial intrusion force and lingual retraction force were simulatively loaded to obtain initial displacement of the anterior teeth and the stresses of each tooth root and periodontal ligament, using three-dimensional finite element calculation software Ansys Workbench 15. The initial displacement of the lateral incisors was close to the bodily movement; and central incisors and lateral incisors slightly extruded. Compared with group A and group C, canine teeth appeared obviously horizontal "arched effect" by crown labial tipping in group B. The stress distribution of the tooth root and periodontal ligament was minimal and uniform in the group C. The 0.016 × 0.022- in stainless steel rectangular wire combined with 0.016- in stainless steel round wire used in the anterior teeth can better control the torque of the maxillary anterior teeth for space close in lingual orthodontics. Moreover, the stress distribution of tooth root and periodontal ligament is even, which is difficult to damage the periodontal ligament or result in external resorption of tooth root.

Este estudio tuvo como objetivo establecer modelos tridimensionales de elementos finitos de microimplantes linguales de alambre recto e investigar los efectos de diferentes patrones de alambre en el desplazamiento inicial de los dientes maxilares anteriores y el estrés del ligamento periodontal y la raíz del diente durante la retracción lingual sobre los dientes anteriores del hueso maxilar en ortodoncia. Se establecieron modelos geométricos tridimensionales del hueso maxilar con dentición utilizando una exploración por tomografía computarizada de haz cónico. Tres tipos de modelos maxilares, incluidos los microimplantes y el dispositivo Duet-Slot Lingual Bracket con tres arcos diferentes (modelo A: 0.016 pulgada × 0.022 pulgada alambre cuadrado de acero inoxidable; modelo B: alambre redondo de acero inoxidable de 0.016 pulgadas; alambre cuadrado de acero inoxidable de 0.016 pulgada × 0.022 pulgada y alambre redondo de acero inoxidable de 0.016 pulgada) ensamblados por el software Unigraphics NX 8.5. La fuerza de intrusión labial y la fuerza de retracción lingual se cargó simultáneamente, para obtener el desplazamiento inicial de los dientes anteriores y las tensiones de cada raíz dental y ligamento periodontal, usando el software tridimensional de cálculo de elementos finitos Ansys Workbench 15. El desplazamiento inicial de los incisivos laterales se relacionaba al movimiento corporal; mientra que los incisivos centrales e incisivos laterales se mostraron ligeramente extruidos. Comparado con el grupo A y el grupo C, los dientes caninos presentaron un "efecto arqueado" horizontal por la inclinación labial de la corona en el grupo B. La distribución del estrés de la raíz del diente y el ligamento periodontal fue mínima y uniforme en el grupo C. El alambre rectangular de acero inoxidable combinado con el alambre redondo de acero inoxidable de 0.016 usado en los dientes anteriores puede controlar mejor el torque de los dientes maxilares anteriores para cerrar el espacio en ortodoncia lingual. Además, la distribución del estrés de la raíz del diente y del ligamento periodontal es pareja, lo que dificulta dañar el ligamento periodontal o provocar una resorción externa de la raíz del diente.

Three-dimensional finite element stress analysis of the mandible first molar under pressure loading / 实用口腔医学杂志

Objective:To establish three-dimensional(3D)finite element model of the mandible first molar,and to study the stress distribution.Methods:3D finite element model of the mandible first molar was constructed by CT image reconstruction technique.Then MIMICS software was used to separate the areas and finish 3D calculation.GEOMAGIC software was applied to modify and generate a NURBS surface in each patch.All components of the model were assembled under the ANSYS preprocessor.Specific material parame-ters were selected to simulate the various restoration and dentin status.The 3D finite element model was applied to analyze the stress distribution of the molar under 1 4 different pressure loading conditions.Results:The 3D finite element model of the mandible first molar was established,which was consistent to the situation observed in the clinical environment.The pressure loading n2,n8,n9,n1 0,n1 1 , n1 2,n1 3,n1 4 can be used to represent the bite pressure.Conclusion:It is a practical and accurate way to establish 3D finite element model by CT image reconstruction technique and reverse engineering software MIMICS and GEOMAGIC.

Micromotion of Cementless Straight and Curved Femoral Stems by Three Dimensional FEM analysis / 대한정형외과학회잡지

PURPOSE: The purpose of this study was to analyze the relative micromotions between the straight and the curved stems during the immediate postoperative stage of noncemented total hip replacement which load simulating the single leg stance and stair climbing. MATERIALS AND METHODS: The authors developed 3-dimensional numerical finite element models implanted with the straight stem, which was composed of a total of 1,170 elements of 8 nodes, and which had a curved stem composed of a total of 885 elements of 8 nodes, and then analyzed the relative micromotions of the straight and curved stems. RESULTS: In the single leg stance, the curved stem was more stable especially in terms of its rotational stability. Rotational displacement accounted for over 90% of the total micromotion in both types of stem and this was highest for the proximal medial portion of the stem, but markedly less distally. Stair climbing produced more micromotion than the single leg stance regardless of the stem configuration. CONCLUSION: It is recommended that surgeons do not allow patient weight bearing until bony ingrowth has been achieved. In the future more attention should be placed upon increasing the initial rotational stability of the two types of femoral stem to prevent loosening by excessive micromotion.

Biomechanical Analysis of Proximal Fitting-Distal Filling Stem and Proximal Fitting- Distal Tapered Stem in Cementless Hip Prosthesis: A 3 Dimensional Finite Element Study / 대한정형외과학회잡지

PURPOSE: This study was undertaken to compare the initial micromotion and stress shielding of a "fit and fill" stem to a "proximal fitting and distal tapered" stem in the early postoperative period using the load simulating single leg stance and stair climbing. MATERIALS AND METHODS: Using the data from 3-D human CT scan, authors developed two types of 3-dimensional finite element total hip replacement model of proximal femur, which were inserted with a "fit and fill" stem and a "proximal fitting and distal tapered" stem. The constructions of stems were based on the OmnifitTM stem (about 13,000 element & 20,000 nodes). We compared micromotion, maximal principal stress and strain energy of each stems. RESULTS: The results indicate that micromotion in a fit and fill stem were slightly lower than that of a tapered stem, especially in stair climbing over that in the single leg stance. The maximum principal stress on the cortex of femur was slightly higher in a tapered stem in the case of single leg stance, and 2 times higher in the case of stair climbing. Strain energy also was much higher in a tapered stem in both single leg stance and stair climbing gait. CONCLUSION: These findings indicate that a tapered stem design could provide more favorable biomechanical benefits rather than a fit & fill stem after cementless total hip replacement.

Construction of three-dimensional finite element models of the first mandibular molar restored with three post and core systems / 实用口腔医学杂志

Objective:To establish three-dimensional(3D) finite element models of the first mandibular molar restored with three post and core systems.Methods:Three 3D finite element models of the restored first mandibular molars were constructed by using CT image reconstruction technique.Then MIMICS software was used to separate the areas and to finish 3D calculation.GEOMAGIC software was applied to modify and generate a NURBS surface in each patch.All components of the models were assembled under the ANSYS preprocessor.Specific materials parameters were selected to simulate the various restoration and dentin status.Results:The 3D finite element models of restored first mandible molars were successfully established,which were consistent to the situation observed in the clinical environment.Conclusion:It is a practical and accurate method to establish three-dimensional finite element models by CT image reconstruction technique and reverse engineering software MIMICS and GEOMAGIC.