下颌角的CT三维重建模拟整形术

目的模拟下颌角整形术，将逆向工程原理应用于下颌角整形手术设计中。方法重建病人术前头部cT颅骨模型，测量相关数据并导入geomagic（V5）软件中，根据东方经典美丽分析面罩模拟下颌骨整形手术，比较原始模型与模拟后模型以确定截骨线和截骨量，最后重建术后CT模型，评价模拟手术效果。结果重建了不同状态下颌骨三维模型，利用模拟手术结果设计了实际手术方案。结论逆向工程原理对于设计下颌整形术方案有明显的临床应用价值。     

一种新型人工颞下颌关节的生物力学分析

目的　建立下颌骨髁突缺损有限元模型,研究新型人工颞下颌关节的应力分布及位移改变。 方法　运用Mimics、Geomagic、Solidworks、ANSYS软件建立含完整牙列的下颌骨右侧髁突缺损有限元模型并分析新型人工颞下颌关节在模拟咬合力加载的情况下假体及下颌骨硬组织的应力分布和位移情况。 结果　下颌骨整体等效应力值均低于20 MPa,最大形变值不超过0.05 mm。 结论　新型人工颞下颌关节能避免过大应力导致的假体断裂和骨质吸收,具有良好的生物力学特性。     

包含颞下颌关节的下颌骨有限元建模

为获得颞下颌关节下颌骨的应力分布提供更为有效的有限元模型。用Mimics10．0导入正常人的颌面CT建立其下颌各部位的有限元模型,通过CAE软件ABAQUS 6．10进行有限元分析。获得了完整的下颌骨、颞下颌关节有限元模型,及后牙咬合状态下模型各部位应力分布等数据。通过分析数据发现,关节盘高应力区主要集中在关节盘中带和后带,而关节盘各部分应力表现为关节盘颊侧应力高于舌侧,顶部应力高于底部,中带平均应力最大,后带次之,前带最小。     

3 种不同髁突头部形态全颞下颌关节假体的生物力学研究

目的 对个性化聚醚醚酮(polyetheretherketone, PEEK)全颞下颌关节假体进行三维建模,通过有限元分析 3 种不同髁突头部形态(原型、80% 原型及圆柱形)假体的应力分布特征,评估 3 种不同髁突头部形态对 PEEK 全颞 下颌关节假体稳定性、关节运动以及关节窝的影响。 方法 建立颅颌面及 PEEK 全颞下颌关节假体有限元分析模 型Ⅰ、Ⅱ、Ⅲ,分析在牙尖交错位、切 颌位、左侧磨牙颌位及右侧磨牙颌位 4 种不同咬合条件下,关节窝假体、髁突 假体、钛钉最大应力,下颌骨应力、应变分布,以及 3 种模型的最大位移。 结果 3 种模型 PEEK 全关节假体及螺钉 的最大应力分别为 35. 22、16. 73 MPa,均低于其材料的屈服强度;模型Ⅰ、Ⅱ、Ⅲ下颌骨最大应力分别为 41. 47、42. 84、 56. 92 MPa,应变分别为 3. 896×10-3 、2. 175×10-3 、4. 641×10-3 。 3 种模型的最大位移为 209. 0 μm,位于模型Ⅲ的左侧下 颌角处。 结论 3 种不同髁突头部形态的个性化 PEEK 全颞下颌关节假体均显示出较为均匀的应力应变分布,但髁 突头部形态为 80% 原型假体的力学效果更好。 研究结果为 PEEK 全颞下颌关节的设计提供一定理论依据。     

建立包含颞下颌关节下颌骨双侧下颌支矢状劈开内固定后的有限元模型

背景：双侧升支矢状劈开截骨已经成为矫正面部畸形的常规方法,运用有限元方法研究双侧下颌支矢状劈开内固定后颞下颌关节及下颌骨的生物力学是一种重要途径。 目的：建立精确、高仿真的双侧下颌支矢状劈开内固定后包含颞下颌关节的下颌骨模型,为研究双侧下颌支矢状劈开内固定后下颌骨及颞下颌关节生物力学提供基础。 方法：螺旋CT扫描后得到DICOM格式数据导入MIMICS软件建立下颌骨三维模型。将三维模型包裹成单一的封闭壳,在ANSYS中进行网格划分及转换,再将模型写入ANSYS软件进行颞下颌关节相应部分的重建并模拟双侧下颌支矢状劈开及术后固定。 结果与结论：运用MIMICS及ANSYS软件建立双侧下颌支矢状劈开内固定后的带有颞下颌关节及下颌骨的三维有限元模型。此模型和人体组织相比,具有生物相似性及几何相似性。双侧下颌支矢状劈开内固定后的模型,可以通过前移、后移、旋转移动远心端,再行各种方式的内固定。所建立的三维有限元模型可以根据实验目的不同,对各个部位施加载荷,用来研究双侧下颌支矢状劈开内固定后不同组织应力及位移的改变,也可以研究不同固定材料对固定后稳定性的影响。中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

颞下颌关节三维有限元建模相关因素分析

颞下颌关节的生物力学研究对理解颞下颌关节病的发生、发展具有重要意义。有限元方法可以分析颞下颌关节各组织受到外力或者发生形变后组织内部的应力和应变情况,但其复杂而且细致的解剖结构导致构建有限元模型的研究总是耗时、昂贵和不可重复。为寻求一种更为快捷、精确的下颌骨三维有限元模型建立方法,提高颞下颌关节有限元建模精度,针对模型与实体几何相似性、生物力学环境仿真模拟等相关因素进行综述。     

两种颌间牵引对下颌骨微种植体及周围影响的三维有限元分析

背景：有限元分析能够模拟正畸治疗方法,并对模型进行生物力学分析,此方法被认为是一种重要的、新的正畸生物力学分析方法。 目的：以三维有限元方法分析下颌骨微种植体及周围牙齿在颌间Ⅱ类、Ⅲ类牵引状况下的应力分布。   方法：选择一个牙列完整(无第三磨牙),咬合关系正常,后牙中性颌,无任何颞下颌关节紊乱症状和体征及病变的成年女性志愿者,24岁。采用螺旋CT对志愿者行闭口位头颅CT断层扫描,应用Ansys多种软件结合的方法,建立颞下颌关节、下颌骨及下颌牙列、微种植体的三维有限元模型,模拟临床颌间Ⅱ类、Ⅲ类牵引对微种植体及周围牙齿应力的影响,并对其进行分析。根据方向分别加载,力值为1 N。 结果与结论：①所建三维有限元模型具有较好的几何相似性。②颌间Ⅱ类牵引：种植钉在上颌在尖牙和第一前磨牙之间,下颌在第二前磨牙和第一磨牙之间。第一磨牙应力分布大于第二前磨牙,但第二前磨牙牙周膜应力分布大于第一磨牙牙周膜。③颌间Ⅲ类牵引：种植钉在上颌在第二前磨牙和第一磨牙之间,下颌在尖牙和第一前磨牙之间。下颌尖牙及其牙周膜应力分布大于下颌第一前磨牙。④微种植体及周围牙齿在进行颌间牵引时应力分布变化微小。     

正畸减数患者后牙前移对颞下颌关节应力影响的三维有限元分析

背景：颞下颌关节紊乱病与颞下颌关节内有高应力密切相关。减数拔牙后伴随着磨牙位置的改变,建立新的咬合关系往往会导致颞下颌关节内应力环境发生改变。目的：在牙尖交错位时,利用三维有限元模型分析正畸减数拔牙后不同程度磨牙前移下颞下颌关节的应力分布。方法：选择在山东青岛市市立医院口腔正畸科就诊的正常牙合患者1例,收集其锥形束CT和MRI数据,分别建立减数前、减数后上下磨牙前移1/3拔牙间隙(拔除4颗第二前磨牙)及减数后上下磨牙前移2/3拔牙间隙(拔除4颗第二前磨牙)的有限元模型,通过建模软件分析牙尖交错位时颞下颌关节各部位的应力分布。结果与结论：(1)减数前后模型中髁突、关节盘、骨关节窝的受力分布基本一致,髁突的应力主要分布于髁突的前部及顶部,关节盘的应力主要分布于关节盘的中带及外侧,颞骨关节窝的应力主要集中分布在关节窝的前部及顶部。与减数前相比,减数后模型中髁突、关节盘及关节窝的等效应力值减小;正畸减数拔牙后,上下磨牙前移1/3拔牙间隙模型中髁突及关节盘的等效应力值小于上下磨牙前移2/3拔牙间隙模型。(2)从生物力学角度上讲,正畸减数拔牙可以降低颞下颌关节的应力,进而提供良好的生物力学环境。     

下颌前突的三维非线性有限元应力分析

下颌前突是最常见的颌面畸形,其下颌骨的力学环境不同于正常人。基于一位下颌前突患者的头部CT片,建立下颌骨的三维有限元模型,关节盘和关节软骨层间考虑接触,对其施加模拟正中咬合的载荷,分析下颌骨不同部位的应力分布特点,为下颌前突的治疗提供参考。结果表明:下颌骨的高应力区出现在乙状切迹和下颌角,分别为13.337MPa和13.850MPa;下颌骨的最大变形发生在颞下颌关节(TMJ)区域。通过与正常人下颌骨的比较,发现下颌骨大部分区域的应力分布较为吻合,但TMJ内的应力分布存在较大的差异,表明下颌前突可能导致TMJ内紊乱症,甚至髁突吸收、关节盘穿孔。可见,除了必要的矫形或手术治疗外,有时还需要针对TMJ进行治疗。     

不同重建工况下Forsus前导下颌后髁突应力、位移的分布变化

目的仿真分析不同工况下推杆式矫治器(Forsus)前导下颌后髁突应力、位移的分布变化,为Forsus临床应用提供参考。方法经Abaqus6.5软件构建Forsus前导下颌三维有限元模型,模拟下颌水平前伸距离分别为3、4、5、6、7 mm,对应下颌垂直打开距离为4、3.5、3、2.5、2 mm的5种重建工况,分析"下颌骨-颞下颌关节"的应力、位移变化和旋转趋势,以评估髁突生长改建的重建方式。结果 5种工况下,最大应力分布在下颌骨髁突、乙状切迹区和髁突颈后份区域。随下颌水平前导的位移量增加,髁突乙状切迹区和髁突颈后份区域应力较缓增大,但仍处于相同数量级(30 MPa);髁突区域应力分布较稳定且没有明显的应力集中。从工况1～5髁突水平方向位移逐渐增大,方向皆向前;髁突垂直向位移平均值也逐渐增大,方向皆向下;下颌骨直接拉伸到指定重建位置时,髁突运动方向也为前下。结论生理性咬合重建的范围,不同程度地前导下颌不会改变髁突软骨附近的应力分布趋势。考虑颞下颌关节生理承受性,严重下颌后缩时可分段前伸以利于髁突生长改建。     

下颌骨骨折固定的建模

目的针对临床中的下颌骨骨折内固定问题,建立小型接骨板模型和下颌骨的独立的几何模型,为下颌骨骨折内固定建模提供一种方法。方法通过Pro/E和ANSYS建立下颌骨骨折内固定治疗模型。首先,对168层下颌骨CT图像进行预处理,突出图像中的下颌骨轮廓,然后采用自编程序提取图中下颌骨内外轮廓点信息,最后通过有限元软件进行自下而上的实体模型建立。在Pro/E中建立螺钉和接骨板的模型,通过IGES格式转入有限元软件,最终建立下颌骨内固定骨折模型。结果和结论本模型可以较方便、真实地模拟下颌骨骨折多发部位的各种内固定方法,为后期的有限元分析提供几何构型和材料分组较为精确的模型。     

骶髂关节解剖型钢板的全骨盆三维有限元模拟

目的在高度仿真的完整骨盆三维有限元模型基础上,模拟使用新设计的解剖型钢板对骶髂关节骨折脱位进行固定,并与普通钢板的模拟固定进行对比,验证和分析新型钢板的性能.方法从CT精确重建髋骨和骶骨模型,采用专门的半自动流线型生物力学有限元网格划分器生成规则的体网格模型,并进一步建立骶髂关节的终板、软骨、关节接触面,和骨盆上的主要韧带组织及耻骨间盘.然后去掉一侧的骶髂关节韧带群模拟骨折脱位,使用新型的骶髂关节解剖型棒-板内固定系统进行固定模拟,同时使用普通钢板替代解剖型钢板建立对比模型,分别进行加载分析受力情况.结果通过使用新的解剖型钢板改进棒一板内固定系统,骶髂关节的最大相对位移值减小了约23%,骨盆主要传承负载区域的最大的应力值降低了约25%.结论新型的解剖型钢板有效地提高了骶髂关节棒-板内固定系统的力学性能,为骨盆骨折的治疗增加了一种更有效的新方法.     

Prediction of fracture location in the proximal femur using finite element models.

Finite element (FE) models of the proximal femur are often used to study hip fracture. To interpret the results of these models, it is important to know whether the models accurately predict fracture location and/or type. This study evaluated the ability of automatically generated, CT scan-based linear FE models of the proximal femur to predict fracture location and fracture type. Fracture location was defined as the specific location of the fracture. Fracture type was a categorical variable defined as either a cervical or a trochanteric fracture. FE modeling and mechanical testing of 18 pairs of human femora were performed under two loading conditions, one similar to joint loading during single-limb stance and one simulating impact from a fall. For the stance condition, the predicted and actual fracture locations agreed in 13 of the 18 cases (72% agreement). For the fall condition, the predicted and actual fracture locations agreed in 10 of the 15 cases where the actual fractures could be identified (67% agreement). The FE models correctly predicted that only cervical fractures occurred in the stance configuration. For the fall configuration, FE-predicted and actual fracture types agreed in 11 of the 14 cases that could be compared (9 trochanteric, 2 cervical; 79% agreement). These results provide evidence that CT scan-based FE models of the proximal femur can predict fracture location and fracture type with moderate accuracy.     

基于Simpleware全颈椎三维有限元模型的构建与分析

目的 利用Simpleware软件构建全颈椎三维有限元模型,并对模型进行验证和分析,为探讨颈椎损伤机制提供可靠模型。方法 基于CT断层扫描图像,利用医学图像处理软件Simpleware、逆向工程软件Geomagic建立C1~7全颈椎三维实体模型,导入Hypermesh进行颈椎网格划分、添加韧带并引入小关节突接触关系等,建立C1~7全颈椎有限元模型,在ANSYS中模拟前屈、后伸、侧弯和轴向旋转工况下颈椎的生物力学性能。结果 建立的模型准确可靠,在前屈、后伸、侧弯和轴向旋转时,活动范围与文献中离体实验和有限元分析结果相近。椎间盘应力集中在椎体受压侧,C4/5最易产生应力集中。结论 建立的C1~7全颈椎有限元模型能够有效模拟颈椎的生物力学特性,为后续颈椎挥鞭样损伤的生物力学研究奠定良好的基础。     

Balancing the spatial demands of the developing dentition with the mechanical demands of the catarrhine mandibular symphysis

The superior transverse torus of the catarrhine mandible has been shown to effectively reduce bending at the symphysis during unilateral postcanine biting. While the adult superior transverse torus contains trabecular bone, the juvenile one is almost entirely filled by developing permanent incisors until their eruption. This study uses finite elements analysis (FEA) to investigate whether the presence of developing incisors in the juvenile symphysis increases strains on the superior transverse torus. Two FE models of a juvenile Macaca fascicularis mandible were created: one included all the developing teeth; the second was modified to remove the incisor tooth crypts by filling them with trabecular bone. The models were loaded identically to simulate static physiological unilateral biting on dp(4) and strain magnitudes, patterns and distributions of the two FE models were compared. The FEA results show a notable increase in strain magnitudes by up to 40% when the developing incisors are present. The results indicate that, in order to maintain the same symphyseal strain magnitudes during chewing, the presence of the incisors in the symphysis necessitates a larger superior transverse torus in the juvenile than would be required if the superior transverse torus did not house the developing incisors. These results highlight the adaptational balance of the symphyseal morphology throughout ontogeny between biomechanics and the spatial demands of the developing dentition. Based on the findings we therefore propose that the spatial requirements of the developing incisors during ontogeny can act as a constraint on the functional adaptation and subsequent adult morphology observed in the catarrhine mandibular symphysis.     

脊柱侧凸三维有限元模型的建立及其意义

目的建立胸腰段脊柱侧凸的三维有限元模型。方法螺旋CT扫描脊柱侧凸患者T6椎体上缘至L1椎体下缘,所得图片经Photoshop处理后导入Simpleware软件,采用实体建模方法构建出每一椎体及椎间盘的实体模型,经过逆向工程软件Geomagic光滑、组装后导入有限元分析软件ABAQUS,进行网格划分建成脊柱侧凸的有限元模型。结果所建模型共划分了232315个单元,356830个节点,模型结构完整,单元划分精细,外观逼真,几何相似性好,能精确测量一定载荷下的应力和位移分布。结论本研究所建有限元模型有助于脊柱侧凸的生物力学研究,对于脊柱侧凸的治疗及个性化矫形支具的设计具有指导意义。     

个性化全骨盆三维有限元建模及骶髂关节骨折脱位模拟

目的建立高度仿真的个性化的完整骨盆三维有限元模型,并在此基础上进行骶髂关节骨折脱位的模拟。方法从CT精确重建独立的左、右髋骨和骶骨实体模型,根据髋骨和骶骨的外形特征,利用专门的流线型生物力学有限元网格划分器生成规则的体网格模型,并进一步建立骶髂关节的终板、软骨、关节接触面,和骨盆上的主要韧带组织及耻骨间盘。在建立的完整模型上去掉一侧的骶髂关节韧带群进行骨折脱位模拟,并与正常的情况进行对比。结果建立了高精度的个性化全骨盆的三维有限元模型,包括左右髋骨和骶骨的皮质骨、松质骨,骶髂关节的终板、软骨和带摩擦的关节接触面,韧带包括骶髂骨间韧带、骶髂前韧带、骶髂后韧带、骶棘韧带、骶结节韧带、耻骨上韧带和耻骨弓状韧带,以及耻骨间盘。正常模型的加载模拟和骶髂关节骨折脱位模拟的预测结果均与文献试验生物力学结果相符合。结论利用专门的生物力学有限元建模工具能建立更复杂更精确的三维有限元模型,成为全骨盆生物力学分析研究的平台和基础。     

Validation of a finite element model of the human metacarpal

Implant loosening and mechanical failure of components are frequently reported following metacarpophalangeal (MCP) joint replacement. Studies of the mechanical environment of the MCP implant-bone construct are rare. The objective of this study was to evaluate the predictive ability of a finite element model of the intact second human metacarpal to provide a validated baseline for further mechanical studies. A right index human metacarpal was subjected to torsion and combined axial/bending loading using strain gauge (SG) and 3D finite element (FE) analysis. Four different representations of bone material properties were considered. Regression analyses were performed comparing maximum and minimum principal surface strains taken from the SG and FE models. Regression slopes close to unity and high correlation coefficients were found when the diaphyseal cortical shell was modelled as anisotropic and cancellous bone properties were derived from quantitative computed tomography. The inclusion of anisotropy for cortical bone was strongly influential in producing high model validity whereas variation in methods of assigning stiffness to cancellous bone had only a minor influence. The validated FE model provides a tool for future investigations of current and novel MCP joint prostheses.     

Intraoral vertical ramus osteotomy improved the stomatognathic function in an elderly patient with mandibular protrusion: a case report

This article reports the successful surgical-orthodontic treatment of an elderly patient with dentofacial deformity and signs and symptoms of temporomandibular disorder (TMD). The patient was a 63-year-old woman with a concave profile due to mandibular protrusion. To correct skeletal deformities, the mandible was posteriorly repositioned by employing intraoral vertical ramus osteotomy (IVRO) following presurgical orthodontic treatment. After active treatment for 31 months, the facial profile was significantly improved and satisfactory occlusion was achieved. In addition, TMD symptoms of clicking sounds on the left side and difficulty in mouth opening were resolved. Regarding the findings of magnetic resonance imaging, anterior disc displacement in the opening phase was improved in the temporomandibular joint on the left side. Furthermore, stomatognathic functions were also improved without any aggravation of age-related problems. In conclusion, surgical repositioning of the mandible using IVRO leads to both morphological and functional improvements even in elderly patients.     

Major gene and multifactorial inheritance of mandibular prognathism

Mandibular prognathism typically shows familial aggregation. Various genetic models have been described and it is assumed to be a multifactorial and polygenic trait, with a threshold for expression. Our goal was to examine specific genetic models of the familial transmission of this trait. The study sample comprised of 2,562 individuals from 55 families. Complete family histories for each proband were ascertained and the affection status of relatives were confirmed by lateral cephalograms, photographs, and dental models. Pedigrees were drawn using PELICAN and complex segregation analysis was performed using POINTER. Parts of some pedigrees were excluded to create one founder pedigrees, so the total N was 2,050. Analysis showed more affected females than males (P = 0.030). The majority of the pedigrees suggest autosomal dominant inheritance. Incomplete penetrance was demonstrated by the ratio of affected/unaffected parents and siblings. The heritability of mandibular prognathism was estimated to be 0.316. We conclude that there is a major gene that influences the expression of mandibular prognathism with clear signs of Mendelian inheritance and a multifactorial component.