不同牵引位点对骨性支抗上颌前方牵引应力分布的影响

发布时间：2018-09-03 09:13

【摘要】：第一部分包含种植体的颅面三维有限元模型的建立目的:建立包含颅面骨骼、骨缝、牙齿和种植体的颅面三维有限元模型。方法:选择一完整8岁男性尸体的头颅标本,通过螺旋CT扫描获得儿童头部二维图像原始DICOM数据,用Mimics 10.0生成颅面骨骼、骨缝、牙齿和种植体的3D模型,通过Geomagic 9.0软件生成相应实体模型,以IGES格式储存。将获得的IGES格式文件按XYZ坐标系导入Abaqus 12.0软件,设置模型网格单元参数,含有颅面骨骼、九条骨缝、八颗牙齿和种植体的颅面三维有限元模型建立完成。结果:建立了包含颅面骨骼、骨缝、牙齿和种植体的颅面三维有限元模型,共划分657,594个单元和990,460个节点,具有较高的几何相似性。第二部分不同牵引位点对骨性支抗上颌前方牵引应力分布的影响目的:采用生物力学方法分析不同牵引位点对骨性支抗前牵引上颌治疗骨性III类错鄈应力分布的影响,寻找面中份发育不足的骨性Ⅲ类错鄈畸形前牵引矫治的最佳牵引位点。方法:利用Abaqus 12.0软件模拟上颌前方牵引的边界条件,在枕骨大孔周围施加位移边界条件,设定模型材料参数,根据临床常用的下述种植体植入部位设定牵引位点,共分四种工况,工况1:乳侧切牙牙冠远中面远中2mm与颈缘龈向5mm交点处牙槽骨;工况2:第一乳磨牙牙冠近中面近中2mm与颈缘龈向5mm交点处牙槽骨;工况3:第一磨牙牙冠近中面近中2mm与颈缘龈向5mm交点处牙槽骨;工况4:第一磨牙牙冠远中面远中2mm与颈缘龈向5mm交点处牙槽骨。采用500g/侧的载荷,与鄈平面前下成角30°,对已建模型进行力量加载。分析比较在不同牵引位点的前牵引力作用下各骨骼、骨缝及牙齿的应力分布,各骨缝及全颅骨的位移趋势,计算Von Mises等效应力并绘制应力分布云图和位移趋势图。结果:1不同牵引位点下各骨缝应力分布特征如下:(1)额颌缝:应力分布以前中2/3部分较为集中,最大应力值均体现在该骨缝前缘。在工况2中,额颌缝应力值最大,应力值范围为2.819×10-2-1.477×10-3mpa。(2)鼻颌缝:在工况1和工况2中,鼻颌缝应力主要集中于上缘和后下缘;在工况3和工况4中,应力分布较为均匀。但在四种工况中,最大应力值均集中于该骨缝的上缘。鼻颌缝应力值在工况1中最大,应力值范围为9.24×10-4-5.296×10-6mpa。(3)颧颌缝:在工况1和工况2中,应力主要集中于前缘,但工况1中范围较大;在工况3中,主要集中于后下部分;在工况4中,主要集中于后缘,且分布较为均匀。颧颌缝的应力值在工况4中最大,应力值范围为1.313×10-2-3.947×10-4mpa。(4)颧额缝:应力主要集中于骨缝边缘,在工况1、2中比3、4中范围稍大,在工况3和工况4中分布相对均匀。颧额缝的应力值在工况4中最大,应力值范围为3.169×10-2-4.952×10-4mpa。(5)颧颞缝:应力分布主要集中于下缘和外侧缘,其中下缘处应力最大。该骨缝在工况3中应力值最大,为1.587×10-2-1.148×10-3mpa,在工况4中应力值次之,为1.367×10-2-1.129×10-3mpa。(6)腭中缝:各工况中腭中缝应力分布较为均匀,在工况1中其应力值最大,为7.300×10-4-6.479×10-6mpa,但相较于其他骨缝偏小。2不同牵引位点下牙齿应力分布特征如下:(1)第一磨牙:在工况1和工况2中,第一磨牙应力分布较为均匀,最大应力位于其近中面牙颈部。在工况3中,应力集中分布于近中面冠根交界处,在工况4中,应力集中分布于远中面根尖1/3处。第一磨牙在工况3中应力值最大,最大应力值为2.03×10-1mpa。(2)第一乳磨牙:在工况1中,第一乳磨牙最大应力集中于腭根根尖1/3处;在工况2中,最大应力集中于腭根靠近根分叉处。在工况3和工况4中,应力集中分布于远中颊根,最大应力分布于根尖部位。第一乳磨牙在工况2中应力值最大,应力值范围为1.061×10-1-4.048×10-4mpa。(3)中切牙、乳侧切牙:在工况1中中切牙应力分布较为均匀;在工况2、3、4中应力集中分布于中切牙根尖2/3。中切牙在工况1中应力值最大,应力值范围为1.815×10-2-2.649×10-7mpa。3不同牵引位点下全颅骨的应力分布特征如下:各工况条件下,载荷加载部位(种植体、眉弓、颞下颌关节窝)周围有明显的应力分布。此外,在工况1中应力出现明显的集中分布,包括鼻梁、鼻背、鼻翼外侧部,并到达鼻额-额颌缝。在工况2、3、4中应力分布主要集中于鼻背两侧及鼻翼外侧部。工况1、2、3中应力集中分布区域逐渐减小,工况4中又逐渐增大。4不同牵引位点下各骨缝的位移趋势如下:额颌缝前部、鼻颌缝前部、颧颌缝前部、颧额缝前上部、腭中缝前部的位移趋势较大,同一骨缝在各工况下位移趋势大致相同。在工况1、2、3中颧颞缝上部的位移趋势较大;在工况4中,颧颞缝上部及外侧缘的位移趋势较大。5不同牵引位点下全颅骨的位移趋势如下:矢状方向上面部以向前的位移趋势为主,自上前牙切缘至颅骨顶端向前的位移趋势逐渐减小,逐渐转换为向后的位移趋势。四种工况比较,鼻根部及鼻背部向前的位移趋势逐渐减小,牙槽突向前的位移趋势逐渐增大。垂直方向上面部主要表现为向上的位移趋势,四种工况中牙齿及牙槽突向上的位移趋势在工况1中最小。结论:1建立了包含颅面骨骼、骨缝、牙齿和种植体的颅面三维有限元模型,该模型精确度高,几何相似性与生物力学相似性好。2种植体支抗前牵上颌,当牵引位点靠近近中时,更易改善面中1/3的凹陷,减少上颌骨的逆时针旋转。
[Abstract]:The purpose of the first part is to establish a three-dimensional finite element model of the skull and face including the skull, suture, tooth and implant. Methods: A complete 8-year-old male cadaver was selected to obtain the original DICOM data of the two-dimensional image of the head of children by spiral CT scanning, and the skull was generated by Mimics 10.0. The 3D models of facial skeleton, suture, tooth and implant are generated by Geomagic 9.0 software and stored in IGES format.The obtained IGES format file is imported into Abaqus 12.0 software according to XYZ coordinate system, and the mesh element parameters of the model are set up, which contain three-dimensional finite element models of craniofacial skeleton, nine bone seams, eight teeth and implant. Results: A three-dimensional finite element model of skull and face including skull, suture, tooth and implant was established, which was divided into 657,594 elements and 990,460 nodes. The geometric similarity was high. Part 2: The effect of different traction sites on the stress distribution of maxillary protraction with osseous anchorage. To analyze the effect of different traction sites on the stress distribution of skeletal class III malocclusion treated by maxillary protraction with bone anchorage, and to find the best traction site for the treatment of midface underdeveloped skeletal class III malocclusion. Boundary conditions, model material parameters, according to the following implant implant placement commonly used in clinic set traction sites, divided into four working conditions, working conditions 1: the distal and distal crown of the primary incisor 2 mm and the cervical gingiva 5 mm intersection point of alveolar bone; working conditions 2: the first primary molar crown 2 mm and the cervical gingiva 5 mm intersection point of alveolar bone; The alveolar bone of a molar crown was located at the intersection of 2 mm proximal to the middle of the crown and 5 mm to the gingival direction of the cervical margin, and the alveolar bone was located at the intersection of 2 mm distal to the middle of the first molar crown and 5 mm to the gingival direction of the cervical margin. The stress distribution of bone, suture and tooth, the displacement trend of suture and skull were calculated. Von Mises equivalent stress was calculated and the stress distribution nephogram and displacement trend diagram were drawn. In working condition 2, the stress value of the frontal and maxillofacial joints is the largest, and the stress range is 2.819 *10-2-1.477 *10-3 mpa. (2) The stress of the nasal and maxillofacial joints is mainly concentrated on the upper and lower edges in working condition 1 and 2, and the stress distribution is more uniform in working condition 3 and 4. (3) zygomatic suture: in condition 1 and 2, the stress mainly concentrates on the leading edge, but the range in condition 1 is larger; in condition 3, the stress mainly concentrates on the lower part; in condition 4, the stress mainly concentrates on the rear edge and distributes uniformly. (4) zygofrontal seam: the stress is mainly concentrated at the edge of the suture, which is slightly larger than that of 3,4 in working condition 1,2, and relatively uniform in working condition 3 and 4. The stress of zygofrontal seam is the largest in working condition 4, and the stress range is 3.169 *10-2-4.952 *10-4 mpa. The stress value of the bone seam is 1.587 *10-2-1.148 *10-3 MPa in working condition 3, followed by 1.367 *10-2-1.129 *10-3 MPa in working condition 4. (6) the middle palate seam: the stress distribution of the middle palate seam is more uniform in all working conditions, and the stress value is 7.300 *10-4-6.47 in working condition 1. The stress distribution characteristics of the first molar were as follows: (1) In working condition 1 and 2, the stress distribution of the first molar was more uniform, and the maximum stress was located in the neck of the mesial teeth. (2) First deciduous molars: in condition 1, the maximum stress of the first deciduous molar was concentrated in 1/3 of the root tip of the palate; in condition 2, the maximum stress was concentrated in the palate root near the root bifurcation. The stress value of the first deciduous molar was the largest in working condition 2, and the stress value ranged from 1.061 *10-1-4.048 *10-4 mpa. (3) Middle incisor, deciduous side incisor: the stress distribution of the middle incisor was more uniform in working condition 1; the stress distribution of the middle incisor in working condition 2, 3, 4 was concentrated in the apical 2/3 of the middle incisor in working condition 1. The stress distribution characteristics of the whole skull under different traction sites are as follows: under different working conditions, the stress distribution around the loading site (implant, eyebrow arch, temporomandibular joint fossa) is obvious. In addition, in working condition 1, the stress concentration appears obviously, including the bridge of nose, the back of nose, the ala of nose. In working condition 2,3,4, the stress distribution was mainly concentrated on both sides of the dorsum of the nose and the lateral part of the ala nasi. In working condition 1,2,3, the stress concentration area gradually decreased, and in working condition 4, the stress concentration area gradually increased. In working condition 1, 2, 3, the displacement tendency of the upper part of the zygotemporal suture was larger; in working condition 4, the displacement tendency of the upper part of the zygotemporal suture and the lateral margin of the zygotemporal suture was larger. The trend of displacement was mainly from the incisal margin of the anterior teeth to the top of the skull. The trend of displacement from the nasal root to the dorsal part of the nose was gradually reduced, while the trend of displacement from the alveolar process was gradually increased. Conclusion: 1. A three-dimensional finite element model of craniofacial skeleton, suture, tooth and implant is established. The model has high accuracy, good geometric and biomechanical similarity. 2 Implants anchor the maxilla forward, and it is easier to pull the maxilla forward when the traction site is close to the middle. Improve the depression of 1/3 in face and reduce the counterclockwise rotation of maxilla.
【学位授予单位】：河北医科大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R783.5

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