| 3D printing technology is a Rapid Prototyping(RP)technology that has gradually emerged in the past two decades or more.It uses reverse engineering software to divide a three-dimensional digital model into layers,and an input 3D printer builds a solid model layer by layer.Wood craft).Different from the traditional mechanical processing technology,the traditional mechanical processing technology is mainly realized by means of casting or cutting.3D printing technology is mainly used in the oral and maxillofacial surgery to print maxillofacial defect repair parts,personalized surgical guides,etc.;in the prosthodontics department is mainly used to print the crown,personalized post and core and partial denture brackets;The Department of Oral Implantology is mainly used for the production of personalized implants and planting guides;the use of occlusal models in orthodontics departments,personalized lingual appliances,and 3D printing techniques also play an important role in invisible care techniques without brackets character of.At present,no reports have been found in the field of orthodontics to use the 3D printing technology to produce personalized orthodontic reinforcement anchorage devices.During my graduate study,I followed the instructor’s use of a 3D-printed personalized enhanced anchorage device to push down the extended maxillary second molar and achieved good clinical results,but whether the material properties of the device had an impact on the clinical therapeutic effect It is not yet known.In this study,a three-dimensional finite element model for the movement of the second molar on the right side of the maxilla was established by establishing a 3D printing personalized orthodontic reinforcement anchorage device(hereinafter referred to as the anchorage device),and the biomechanical evaluation of the moving tooth and the anchor tooth was conducted to study the anchorage device.The effects of the material properties of the material on the biomechanical properties of tooth movement.The topics are mainly divided into three parts:Part Ⅰ: The establishment of a three-dimensional finite element model for two kinds of anchorage devices moving the maxillary right second molarHigh-precision CT scans and Mimics 3D reconstructions were used to obtain high-simulation 3D geometric models of the maxillary and maxillary dentitions.Digitally designed with 2-sided second premolars and first molars as anchoring teeth tongue-side adhesives in 3-matics software.The knot-type towing hook TPA(the tongue-side TPA-type anchorage device)and the maxillary right first molar to the left first molar are the anchorage-tooth-side plywood-type accompanying traction hook anchorage devices(the tongue-side plywood anchoring device),Import it into geomagic 12.0 to generate a solid model,and generate an orthodontic tongue solid model in Solidworks software.Introduce the above solid geometry model into finite element ANSYS Workbench,in which the maxillary bone is set to orthotropic,non-Homogeneous linear elastic material,the periodontal membrane is set as an anisotropic,non-homogeneous non-linear elastic material,tooth,anchorage device,and tongue are set as homogeneous,isotropic linear elastic materials,establish X,Y,Z three-dimensional reference frame of reference,and ultimately generate a personalized three-dimensional finite element model of orthodontic reinforcement anchorage device moving maxillary second molar.When the material properties of the anchorage device are set to different elastic moduli,150 g of tractive force is applied to the traction hook and the tongue attached to the right maxillary second molar using a spring unit to calculate the initial motion of the moving tooth and the anchor tooth,respectively.Displacement and periodontal membrane hydrostatic pressure.Part Ⅱ: Three-dimensional finite element analysis of lingual TPA anchorage device for moving maxillary second molarThe second molar of the right side of the maxilla(moving tooth)is tilted in the direction of the buccal tongue to the root of the tooth and the displacement of the crown is much larger than the displacement of the root,and it tends to move downward in the vertical direction.In the upper right maxillary second premolar,the first molar was basically in the buccal and lingual direction of the crown and cheek,and the inclination of the root tongue of the first molar was greater,and the displacement tendency of the crown was greater than that of the tooth root,and the vertical direction(occlusal)was In the elongate movement,the left second premolar has a tendency to move from the bucco-lingual direction to the root cheek in the direction of the buccal tongue,and moves downward in the direction of the temporal direction in the vertical direction.The first molar on the left had no apparent movement tendency.When the material elastic modulus is small,the left maxillary second premolar has the largest displacement tendency,and is significantly larger than other anchoring teeth.The force of the anchoring tooth is mainly concentrated on a single tooth.As the elastic modulus of the material increases,the left The movement trend of the lateral maxillary second premolar decreased,the movement tendency of the right maxillary first molar increased,and the force of the anchoring tooth was more dispersed.When the elastic modulus of the material is small,the hydrostatic pressure of the periodontal ligament is also smaller and does not exceed the upper limit of the capillary pressure.With the increase of the elastic modulus of the material,the hydrostatic pressure of the periodontal ligament increases.The maxillary first molar periodontal ligament of the right maxillary mandibular was subjected to the greatest tensile stress,and the right maxillary second molar periodontal membrane was the most affected by the compressive stress of the proximal and middle teeth.Clinically,it is recommended to use materials with large elastic modulus.However,it is necessary to reasonably design the loading force so as not to exceed the periodontal ligament hydrostatic pressure and cause root absorption.Part Ⅲ: Three-dimensional finite element analysis of moving maxillary second molars with lingual splint anchorage deviceThe trend of the displacement of the second molar of the right maxillary is similar to that of the lingual TPA.The right maxillary first molar,the second premolar,and the first premolar of the anchoring tooth are in the buccolingual direction and the cheeks of the crown and the tongue are tilted.In the vertical direction(occlusal)to the extension of the movement,the remaining anchor teeth have no obvious tendency to move,the orthodontic correction of the reaction force is not evenly distributed to the anchor teeth,in the tooth closer to the hook The upper initial trend is more pronounced.When the elastic modulus of the material is small,the displacement of the right maxillary first premolar is much larger than that of the rest of the teeth.As the elastic modulus of the material increases,the displacement of the right maxillary second premolar and the first molar increases,but still Less than the first premolar.The displacement of the right maxillary second molar is smaller than that of the first premolar,which may be concentrated in the maxillary first premolar with the orthodontic reaction.The area of the periodontal ligament of the first premolar is smaller than that of the second molar.The displacement of the first premolar is greater than that of the second molar.This prompted us to choose a material with a higher modulus of elasticity to print a personalized anchorage device in the clinic,and to reasonably design the position of the towing hook. |
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