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1.
咀嚼肌牵动的下颌骨三维有限元建模与数值分析   总被引:4,自引:1,他引:3  
目的:应用有限元方法分析咀嚼肌牵动的下颌骨应力状态。方法:采用数字中国人下颌骨CT图像三维重建,生成有限元模型,通过解剖学研究和测量,确立颞肌、咬肌、翼内肌、翼外肌的附着部位面积和肌力线方向。结果:建立了咀嚼肌牵动的下颌骨生物力学分析模式,有限元计算得到下颌骨应力分布状态,Von Mises应力主要集中于髁突,冠突,咀嚼肌附着部位和磨牙区,当右侧第1磨牙与第2磨牙咀嚼模拟时应力峰值为20.61MPa.当第1前磨牙与第2前磨牙咀嚼模拟时应力峰值达到了22.09MPa。结论:有限元分析技术,结合下颌骨血管神经走向及He力与咀嚼功能测定等,为下颌骨截骨术和骨牵张术提供了一种术前设计的定量方法。  相似文献   

2.
通过Pro/E和ANSYS建立下颌骨颏部骨折内固定的三维有限元模型,并模拟了各种功能状态下的边界约束。使用计算机图像处理软件对CT扫描图像进行预处理,然后采用自编程序获取下颌骨解剖结构的三维坐标数据,用ANSYS建立下颌骨的三维有限元模型。采用数值化建模软件Pro/E建立小型接骨板-螺钉固定体系统的实体模型。模拟下颌骨颏部正中骨折坚强内固定治疗,建立该内固定治疗的有限元模型。通过改变各组咀嚼肌力的大小,进行了三种咬合状态的边界约束。获得了形态逼真、相似性好的下颌颏部骨折内固定后的三维有限元模型,并模拟了各功能状态下的边界约束,为后期的生物力学分析奠定了基础。  相似文献   

3.
下颌角整形术对下颌骨应力以及颞下颌关节功能的影响   总被引:1,自引:0,他引:1  
目的分析基于东方经典美丽分析面罩的下颌角整形术对人体下颌骨及颞颌关节功能的影响。方法获取病人术前和术后头部CT图像数据,通过Simpleware有限元建模软件生成计算模型,利用Abaqus软件观察手术前后模型上的应力分布及数值大小。结果获得了具有良好形态的下颌骨三维有限元模型,根据在不同部位施加不同负荷模拟模型各部分的力学改变,发现手术前后下颌骨部及关节附近的应力分布有差异。结论基于东方经典美丽分析面罩的下颌角整形术,手术前后对病人的下颌骨及颞颌关节附近的应力减小。  相似文献   

4.
角膜的刚度降低是导致圆锥角膜的关键因素,角膜中胶原纤维刚度和纤维分散程度与角膜生物力学性能密切相关。本文通过建立基于角膜微结构即考虑胶原纤维的准分子激光原位角膜磨镶术(LASIK)术前和术后人眼角膜有限元模型,模拟了可视化角膜生物力学分析仪的检测过程,并与临床实际检测结果对比,确定屈光手术前后人眼角膜材料的超弹性本构参数及角膜胶原纤维刚度模量。研究发现LASIK术后,角膜胶原纤维刚度模量较术前明显增大,并与中央角膜厚度(CCT)高度相关;术前术后角膜胶原纤维刚度模量与对应中央角膜厚度的预测关系分别为:k_(1术前)=exp(9.14-0.009CCT_(术前)),k_(1术后)=exp(8.82-0.008CCT_(术后))。根据本文的研究结果,可由患者的中央角膜厚度值估算其术前术后胶原纤维刚度模量,进而建立与患者实际情况更相符的个性化角膜模型,为更准确地预测角膜安全手术切削量提供理论参考。  相似文献   

5.
目的 设计一种具有多孔和支撑结构的个性化钛下颌修复体,通过有限元分析其应力分布特征,评估修复体的临床应用价值及应用前景。方法 拔除比格犬右侧下颌第4前磨牙及磨牙,愈合3个月后拍摄螺旋CT并建立下颌三维模型,模拟手术过程切除3 cm下颌骨并用个性化修复体重建,该修复体由基牙、支柱、实体单元、多孔单元及固位单元组成。建立个性化钛下颌修复体有限元模型A,分析负荷时修复体的峰值应力,当构成假体每部分的最大应力均小于其材料的屈服强度时进行下一步研究;构建假体、下颌骨以及螺钉装配完成的有限元模型B,加载咀嚼力,记录下颌骨的应力、应变及位移分布。结果 当基牙垂直加载载荷100 N时,修复体实体、多孔结构的峰值应力分别为147.03、75.36 MPa,均小于其材料的屈服强度;皮质骨、松质骨的的峰值应力分别为53.713、4.216 7 MPa,应变分别为3.753 6、3.562 5;修复体最大位移338.3 μm。结论 以犬下颌骨为例,通过有限元分析表明,设计的具有多孔和支撑结构的个性化修复体应力分布均匀,具有较好的力学性能。研究结果为修复下颌骨缺损的假体设计提供了一种新方法。  相似文献   

6.
下颌角的CT三维重建模拟整形术   总被引:2,自引:0,他引:2  
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。  相似文献   

7.
目的:建立犬下颌骨节段缺失的有限元模型。方法:运用Mimics软件读取基于实验犬下颌骨CT资料的DICOM数据形成几何模型,在Magics软件中使用cut工具对几何模型进行切割,模型由缺损侧和非缺损侧下颌骨、重建钛板组成,每个部分依靠Magics的粘接功能粘在一起,生成实体单元后在MARC软件中完成模型的力学分析。结果:建立了犬下颌骨节段缺失的有限元模型,可模拟牵张过程,观察任意点的应力、位移情况,并可选取模型的任意部分,查看其相应计算结果。结论:犬下颌骨节段缺失的有限元模型的建立为进一步研究节段缺损下颌骨的各种生物力学状况奠定了基础。  相似文献   

8.
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。  相似文献   

9.
目的 利用拓扑优化确定最优下颌骨植入物固定板的布局,并设计高承载能力的个性化下颌骨植入物固定板。 方法 以典型的下颌骨缺损模型为例,构建考虑骨骼和支架材料特性的下颌骨有限元模型。 对模型进行拓扑优化分析,设计个性化下颌骨植入物固定板。 通过模拟分析常规固定板系统与个性化固定板系统下颌骨、固定板、 螺钉的应力分布,评估个性化下颌骨植入物固定板的力学特性。 并结合 Gibson-Ashby 模型,设计弹性模量与皮质骨相当的多孔面心立方晶格结构假体,最终确定最终支架方案。 结果 通过安装个性化下颌骨植入物固定板,下颌骨、接骨板、螺钉的峰值应力分别 55. 86、291. 1、122. 53 MPa,分别比安装常规固定板降低 9. 8% 、32. 0% 和14. 6% 。 结合个性化下颌骨植入物固定板与多孔结构的设计方案,得到最优孔隙率为 71. 6% 的三维多孔支架模型。 结论 本研究设计的个性化下颌骨植入物固定板显著降低假体的峰值应力,提高支架的可靠性。 并且结合激光选区熔化(selective laser melting, SLM)技术,可以快速制造出性能优异的个性化假体,以满足紧迫的时间需求。  相似文献   

10.
目的对已截骨的髋臼块进行不同角度旋转,以模拟手术中髋臼块需调节的不同角度,通过分析髋关节周围软骨接触应力以及接触面积确定最佳角度,为髋臼截骨提供个体化方案。方法建立髋关节发育不良(development dysplasia of hip,DDH)和正常有限元模型,探讨发育不良髋臼形态特征以及应力集中原因。对DDH模型模拟截骨术,通过髋臼块的向前方和侧方旋转的不同角度组合得到共计20个截骨术后骨盆模型,对比分析模型在模拟单腿站立情况下最优结果的差异。结果正常模型髋臼软骨最大接触压力为7.85 MPa。DDH模型髋臼软骨最大接触压力为13.42 MPa,模拟截骨术后最优解接触压力下降至8.49 MPa,且接触力分布改善更明显。结论改变前侧旋转角度可以明显改善接触压力分布和大小并且远离术前病变区域,对术后效果有积极影响。手术前基于每位患者的实际情况制定个性化截骨方案对于手术效果至关重要。  相似文献   

11.
For practical application of a liver assist system with a tissue-conjugated hollow fiber membrane (HFM) bioreactor used in an extracorporeal therapy, it would require a highly sophisticated HFM which has both hemocompatibility on one side and cytocompatibility on the other side. In this study, we present a cellulose acetate (CA) HFM modified with 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymers (PMB30 (MPC-co-n-butyl methacrylate) and PMA30 (MPC-co-methacrylic acid) for preparing a novel liver assist HFM bioreactor. A CA/PMB-PMA30 HFM modified asymmetrically on the inner and outer surface with the PMB30 and PMA30 was prepared successfully. Analysis with an X-ray photoelectron spectroscope showed that the intensity of the phosphorus atom attributed to the MPC units on the outer surface of the modified HFM was stronger than that of the inner surface. The PMA30 was immobilized on the outer surface of the CA/PMB30 blend HFM by a chemical condensation reaction. The CA/PMB-PMA30 HFM showed good water and solute permeability in comparison with the CA HFM. The morphologies of the adherent hepatocytes were round in shape in comparison with the cells that adhered on CA HFM. Furthermore, hepatocytes cultured on the inner surface of the CA/PMB-PMA30 HFM showed higher functional expression in terms of urea synthesis and albumin synthesis than that of the CA HFM.  相似文献   

12.
Hereditary folate malabsorption (HFM) is a rare autosomal recessive disorder. Severe folate deficiency in HFM can result in immunodeficiency. We describe a female infant with HFM who acquired severe Pneumocystis pneumonia. The objective of the present study was to elucidate her immunological phenotype and to examine the time course of immune recovery following parenteral folate therapy. The patient demonstrated a combined immunodeficiency with an impaired T cell proliferation response, pan-hypogammaglobulinemia, and an imbalanced pro-inflammatory cytokine profile. She had normal white blood cell count, normal lymphocyte subsets, and normal complement levels. Two novel mutations were identified within the SLC46A1 gene to produce a compound heterozygote. We confirmed full recovery of her immunological and neurophysiological status with parenteral folate replacement. The time course of recovery of her immunological profile varied widely, however. HFM should be recognized as a unique form of immunodeficiency.  相似文献   

13.
Zhang Q  Wang N  Xu T  Cheng Y 《Acta biomaterialia》2012,8(3):1316-1322
Poly(amidoamine) (PAMAM) dendrons were prepared from hollow fiber membranes (HFM) consisting of bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO) in a stepwise manner. The prepared HFM were characterized by Fourier transform infrared spectroscopy, elemental analysis, and scanning electron microscopy. The drug loading efficiency and release behavior of the PAMAM dendronized HFM were evaluated using sodium salicylate, sodium methotrexate, and Congo red as model drugs. The results suggest that PAMAM dendronized HFM can be effectively loaded with a variety of drugs and prolong the release of these drugs. The drug loading and release characteristics of the HFM depend on the generation of PAMAM dendrons grafted on the membranes. The prepared PAMAM dendronized BPPO HFM are promising scaffolds in drug delivery and tissue engineering.  相似文献   

14.
The phenotypes of hemifacial microsomia-VATER, VATER, and sirenomelia patients suggest a sequence of overlapping developmental abnormalities. The malformations of 247 hemifacial microsomia (HFM) patients with one or more anomalies in other body regions were analyzed and compared with those of 255 VATER and 101 sirenomelia patients studied in the same fashion. The HFM patients were analyzed in four subgroups delineated by the number of their concomitant VATER ascertainment abnormalities (VAA). Three or more VAA occurred in 33 HFM patients who were designated to have the HFM-VATER phenotype and while no significant alteration of the HFM phenotype was found, there were notable differences in the analyses of the 20 malformation categories studied. Analyzed in separate heart and blood vessel (BV) categories, occurrences of BV defects in HFM patients with 0–1 VAA were low (4–6%) and due to anomalies other than sigle umbilical arteries (SUA). The BV abnormalities increased to 20% in the HFM with two VAA, HFM-VATER, and VATER phenotypes with equal occurrence of SUA and other BV anomalies. The incidence of SUA was markedly increased (64%) in the sirenomelia. Heart defects rose from 22% to 40% with the increasing VAA in individual HFM patients but were less in VATER (29%) and sirenomelia (21%) patients and were attributed to complex conotruncal, and other early embryonic anomalies. Unilateral agenesis of paired organs systems occurred frequently and, possibly, can be attributed to an absent blood supply. Each phenotype of the sequence also had increased VAA, rib/vertebrae hypersegmentation, and monozygotic twinning. The variation in the incidences of malformations in the three phenotypes can be attributed to their relative location in the craniocranial organogenesis sequence of normal human embryologic development. © 1993 Wiley-Liss, Inc.  相似文献   

15.
A review of the anatomical changes in patients with various "first arch" syndromes shows that some anomalies (e.g., micrognathia, ear defects) generally appear together. This study tested the hypothesis that the mandible, zygomatic arch, and middle ear ossicles are a developmental field (i.e., when any of these structures is anomalous, the other two will be also). The hypothesis was tested using data from 25 patients with mandibulofacial dysostosis (MFD) and 40 patients with hemifacial microsomia (HFM). Analysis of the pooled data showed that the hypothesis of character association was generally supported. However, the medians suggested that different factors probably played a role in determining how these three anatomical structures were associated in MFD and HFM. Errors in chondrogenesis may have been primarily responsible for the HFM phenotype. Alterations in Meckel and palatoquadrate cartilages would account for the size and shape changes observed in the ossicles and mandible, while changes in cranial base cartilages may explain the changes noted in the zygomatic arch. Since all three structures were equally affected in MFD, it is problematic to use an interference with chondrogenesis as an explanation for the phenotype. We conclude that although the mandible, zygomatic arch, and middle ear ossicles appear to form a "developmental field," the association between structures varies for HFM and MFD. The relatively lesser involvement of the zygomatic arch in HFM than in MFD suggests different pathogeneses for the two diagnostic groups and maybe a useful criterion for judging animal models of HFM.  相似文献   

16.
HFM1 is a meiosis‐specific gene and expressed in germ‐line tissues. More recently, evidence has indicated that variations in HFM1 gene could be causative for primary ovarian insufficiency (POI), also known as premature ovarian failure. The aim of this study was to investigate the association between HFM1 gene variants and sporadic POI in Chinese women. A total of 138 POI patients and 316 healthy controls (matched for ethnic background, sex, and age of the patients) were recruited in this study. We screened the entire HFM1 coding region by direct sequencing in all subjects and identified six variants of HFM1 gene in POI group, namely c.148G>A/p.Glu50Lys, c.1241A>C/p.His414Pro, c.2325C>A/p.Phe775Leu, c.3367T>C/p.Ser1123Pro, c.3580C>T/p.Arg1194Cys, and c.1686‐1G>C. The variation rate of HFM1 in POI group is significantly higher than control group (p < 0.01). The p.His414Pro and p.Arg1194Cys were predicted to be probably damaging to the HFM1 protein function, while p.Glu50Lys, p.Phe775Leu and p.Ser1123Pro mutants might not have any deleterious effect on the structure or function of the protein by online predictors. Taken together, our data suggested that HFM1 gene might be associated with primary ovarian insufficiency in Chinese population.  相似文献   

17.
The cause of hemifacial microsomia (HFM) is currently the subject of much investigation. Despite a large body of clinical and experimental data, little is certain other than the heterogeneity of this malformation complex. Here we suggest that some of the cases previously designated as being multifactorial in origin may be interpreted instead as resulting from a single-gene mutation, by applying a stochastic single-gene model. A variety of models of the pathogenesis of HFM have been described, including the proposal that local embryonic haemorrhage is a causal mechanism. More recently, it has been suggested that an interference in chondrogenesis is primarily responsible for the HFM phenotype. In this paper direct experimental evidence, based on surgical interference of mandibular development in the chick embryo, is applied in favour of the latter concept. In particular, asymmetrical perturbation of Meckel's cartilage has been shown to result in asymmetry of the mandible, and it is proposed that, irrespective of cause, the skeletal pathogenesis of HFM primarily involves the auriculofacial cartilage model.  相似文献   

18.
Obesity has important health consequences, including elevating risk for heart disease, diabetes, and cancer. A high-fat diet is known to contribute to obesity. Little is known regarding the effect of a high-fat diet on pulmonary function, despite the dramatic increase in the prevalence of respiratory ailments (e.g., asthma). The purpose of our study was to determine whether a high-fat meal (HFM) would increase airway inflammation and decrease pulmonary function in healthy subjects. Pulmonary function tests (PFT) (forced expiratory volume in 1-s, forced vital capacity, forced expiratory flow at 25–75% of vital capacity) and exhaled nitric oxide (eNO; airway inflammation) were performed in 20 healthy (10 men, 10 women), inactive subjects (age 21.9 ± 0.4 years) pre and 2 h post HFM (1 g fat/1 kg body weight; 74.2 ± 4.1 g fat). Total cholesterol, triglycerides, and C-reactive protein (CRP; systemic inflammation) were determined via a venous blood sample pre and post HFM. Body composition was measured via dual energy X-ray absorptiometry. The HFM significantly increased total cholesterol by 4 ± 1%, and triglycerides by 93 ± 3%. ENO also increased (p < 0.05) due to the HFM by 19 ± 1% (pre 17.2 ± 1.6; post 20.6 ± 1.7 ppb). ENO and triglycerides were significantly related at baseline and post-HFM (r = 0.82, 0.72 respectively). Despite the increased eNO, PFT or CRP did not change (p > 0.05) with the HFM. These results demonstrate that a HFM, which leads to significant increases in total cholesterol, and especially triglycerides, increases exhaled NO. This suggests that a high-fat diet may contribute to chronic inflammatory diseases of the airway and lung.  相似文献   

19.
To study the removability of pro-inflammatory cytokines by hemofiltration (HF), we performed experimental HF with various high-flux membranes (HFM) using a closed circuit system filled with monocyte-free human plasma, which contained TNFalpha, IL-1beta, and IL-6. Plasma and filtrate samples were taken before and 1, 2, 3, and 4 hours after the initiation of HF, and each cytokine was determined by enzyme-linked immunosorbent assay. IL-1beta was well removed through filtration during experimental HF using HFM (PAN>CTA>PMMA>PS). TNFalpha and IL-6 were only minimally filtered out by HF using HFM. TNFalpha was removed to some extent by using PS, and IL-6 was partially removed by using PMMA during experimental HF through other mechanisms, such as adsorption, than the filtration. IL-1beta and IL-6 were effectively removed by HA using charcoal adsorbent column, especially during the first 2 hours, while TNFalpha was only partly removed.  相似文献   

20.

Introduction

Many environmental and dietary influences can cause immune cells to produce biological mediators that increase airway inflammation. A high-fat meal (HFM) is one stimulus that increases airway inflammation in healthy individuals. Supplementation with omega-3 fatty acids can reduce inflammation systemically and may be beneficial to the airways.

Purpose

To determine if omega-3 fatty acid supplementation via fish oil would mitigate the airway inflammatory response induced by a single HFM.

Methods

Seventeen non-asthmatic men (22 ± 2 years.) were supplemented with 3,000 mg × day?1 fish oil or a placebo for 3 weeks. Fractional exhaled nitric oxide (FENO; a marker of airway inflammation), impulse oscillometry (a measure of respiratory impedance), pulmonary function, and triglycerides were measured prior to and 2 h following a HFM.

Results

Following a HFM, triglycerides increased in both fish oil and placebo groups compared to pre-HFM (~59 and ~49 %, respectively, p < 0.05). The percent increase in FENO was greater in the placebo group compared to the fish oil group (25.7 ± 16.7 vs. ?1.99 ± 10.5 %, respectively, p < 0.05). A significant correlation was observed between blood triglycerides and FENO in the placebo group (r = 0.61; p < 0.05), but not the fish oil group (p = 0.21).

Conclusion

A single HFM increases airway inflammation and omega-3 fatty acid supplementation via fish oil protects against HFM associated changes in airway health.  相似文献   

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