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.

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.