TeeTester与T-ScanⅢ咬合分析仪对正常牙合青年学生咬合力特征的比较

背景：TeeTester和T-ScanⅢ两种咬合分析仪在口腔临床各领域已被广泛应用,国内对两种仪器的使用尚未见到对比数据。 目的：应用TeeTester与T-ScanⅢ两种咬合分析仪研究正常牙合青年学生的咬合特征,并比较两系统咬合分析的差异。 方法：采用TeeTester咬合系统V3.2.0记录13例正常牙合受试者在牙尖交错位状态下的左右侧咬合力分布百分比、牙合力中心点位置、牙合力不对称指数、前牙咬合力占牙合力总值的百分比,采用T-ScanⅢV8.01咬合分析仪记录13例正常牙合受试者在ICP时的上述指标,并在25%,50%,75%,100%最大咬合力时的4个时段对上述各项指标进行分析。检测数据导入SPSS19.0软件进行统计。 结果与结论：①TeeTester与T-ScanⅢ两系统所测得的左右侧咬合力分布百分比差异均无显著性意义(P > 0.05)。②两系统所测得的所有受试者牙合力中心点绝大多数在规定灰圈内,且均位于前磨牙区。两系统所测得   牙合力中心点距中线的垂直距离、牙合力中心点偏移方向,差异均无显著性意义(P > 0.05)。③两系统所测得的牙合力不对称指数差异无显著性意义(P > 0.05)。④TeeTester所测得的前牙咬合力占总牙合力的百分比大于T-ScanⅢ所测结果,且在50%,75%,100%最大咬合力时差异有显著性意义(P < 0.05)。结果说明,①正常牙合者左右侧咬合基本平衡。②左右侧咬合力分布百分比、牙合力中心点、牙合力不对称指数可以作为临床上判断咬合是否正常的指标。③TeeTester与T-ScanⅢ在前牙咬合力占总牙合力百分比的测量方面存在差异,需要继续关注和研究。  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     

Using occlusal wear information and finite element analysis to investigate stress distributions in human molars

Simulations based on finite element analysis (FEA) have attracted increasing interest in dentistry and dental anthropology for evaluating the stress and strain distribution in teeth under occlusal loading conditions. Nonetheless, FEA is usually applied without considering changes in contacts between antagonistic teeth during the occlusal power stroke. In this contribution we show how occlusal information can be used to investigate the stress distribution with 3D FEA in lower first molars (M(1)). The antagonistic crowns M(1) and P(2)-M(1) of two dried modern human skulls were scanned by μCT in maximum intercuspation (centric occlusion) contact. A virtual analysis of the occlusal power stroke between M(1) and P(2)-M(1) was carried out in the Occlusal Fingerprint Analyser (OFA) software, and the occlusal trajectory path was recorded, while contact areas per time-step were visualized and quantified. Stress distribution of the M(1) in selected occlusal stages were analyzed in strand7, considering occlusal information taken from OFA results for individual loading direction and loading area. Our FEA results show that the stress pattern changes considerably during the power stroke, suggesting that wear facets have a crucial influence on the distribution of stress on the whole tooth. Grooves and fissures on the occlusal surface are seen as critical locations, as tensile stresses are concentrated at these features. Properly accounting for the power stroke kinematics of occluding teeth results in quite different results (less tensile stresses in the crown) than usual loading scenarios based on parallel forces to the long axis of the tooth. This leads to the conclusion that functional studies considering kinematics of teeth are important to understand biomechanics and interpret morphological adaptation of teeth.     

舌侧集中牙合与解剖式双侧平衡牙合应用于全口义齿修复的系统评价

背景：牙合型是制作全口义齿成功的关键,临床上如何选择合适的牙合型一直是困扰修复科医师的问题。 目的：系统评价舌侧集中牙合和解剖式双侧平衡牙合应用于全口义齿修复的临床效果。 方法：用关键词“complete denture” ,“edentulous”,“occlusion” ,“balanced”,“lingualized,” “anatomic”,计算机检索Cochrane图书馆临床对照试验库、Pubmed/Medline数据库、EMBASE数据库、万方数据库、CNKI中国知网数据库及中国生物医学文献库,语言设置为中文和英文,年限设置均从创刊到2013年10月,检索相关文献,此外用手工检索11种口腔医学杂志和相关文献的参考文献。由两位评价员独立进行文献筛选、资料提取和质量评价,共检索出628篇文献。 结果与结论：按照纳入和排除标准,纳入5篇文献。其中1篇文献研究证明舌侧集中牙合在患者固位力满意度上高于双侧平衡牙合(P < 0.05)。其中1篇研究证明舌侧集中牙合在患者对“进食有问题”、“需要避免特殊食物”的评比分数上低于完全双侧平衡牙合(P < 0.05),在“不舒适假牙”的评比分数上高于完全双侧平衡牙合(P < 0.05)。其中1篇文献证明舌侧集中牙合应用于重度牙槽骨吸收患者具有更好的咀嚼效率和能较好保护牙槽骨(P < 0.05)。其他2篇文献研究中舌侧集中牙合与双侧平衡牙合在患者总体满意度等研究的比较结果上差异无显著性意义。结果证实,舌侧集中牙合具有与解剖式双侧平衡牙合相似的患者满意度、咀嚼效率、美观和发音,对严重牙槽骨吸收患者有更好的咀嚼效率和保护牙槽骨的作用。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

咬合刺激调控胶原骨粉修复骨缺损过程中骨改建的形态学分析

背景：咬合刺激对于颌骨的功能及改建至关重要,但人们对其调节骨移植修复骨缺损过程中骨改建的作用尚缺少清楚的认识。 目的：应用形态学方法分析咬合刺激对胶原骨粉修复骨缺损中骨改建的可能调控作用。 方法：在成年SD大鼠左侧下颌骨及顶骨区分别建立标准骨缺损模型,随即植入胶原骨粉充填骨缺损区。术后12周,通过X射线、苏木精-伊红染色、Gomori染色、抗酒石酸酸性磷酸酶染色及骨形成蛋白2免疫组织化学染色观察两骨缺损区的差异。 结果与结论：下颌骨及顶骨骨缺损区均有新骨形成,顶骨骨缺损区的板层骨形成量明显多于下颌骨骨缺损区,新骨形成矿化度明显高于下颌骨骨缺损区,说明顶骨骨缺损区的骨改建优于下颌骨骨缺损区;顶骨骨缺损区抗酒石酸酸性磷酸酶及骨形成蛋白2积分吸光度值均低于下颌骨骨缺损区,说明顶骨骨缺损区的破骨细胞及成骨细胞活性低于下颌骨骨缺损区。表明咬合刺激可能通过影响骨的矿化及成熟而导致下颌骨骨缺损修复过程中骨改建的延迟。 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

Physiological Distal Drift in Rat Molars Contributes to Acellular Cementum Formation

Occlusal forces may induce the physiological teeth migration in humans, but there is little direct evidence. Rat molars are known to migrate distally during aging, possibly caused by occlusal forces. The purpose of this study was to determine if a reduction in occlusion would decrease teeth migration and affect associated periodontal structures such as cementum. To reduce occlusal forces, the right upper first molar (M1) in juvenile rats was extracted. The transition of the position of upper second molar (M2) and formation of M2 cementum was followed during aging. From the cephalometric analyses, upper M2 was located more anterior compared with the original position with aging after M1 extraction. Associated with this “slowing‐down” of the physiological drift, cementum thickness on distal surface, but not on mesial surface, of M2 root was significantly increased. The accumulation of alizarin red as vital stain indicative of calcification, was observed in the distal cementum of M2 root only on the side of M1 extraction. Extraction of M1 that results in less functional loading, distinctly attenuates the physiological drift only in the upper dentition. The decreased physiological drift appears to activate acellular cementum formation only on distal surface of M2 root, perhaps due to reduced mechanical stress associated with the attenuated distal drift. In conclusion, the physiological distal drift in rat molars appears to be largely driven by the occlusal force and also affects the formation of acellular cementum. These findings provide additional direct evidence for an important role of occlusal forces in tooth migration. Anat Rec, 2013. © 2013 Wiley Periodicals, Inc.     

颅底曲度与后牙牙合平面倾斜度对矢状骨面型形成的影响

文题释义： 矢状骨面型：矢状向上，上下颌骨的位置关系及其所导致的错牙合畸形类型。 牙合 平面：由连接上下颌切牙覆牙合中点、上下颌第1磨牙覆牙合中点确定的假想平面。 后牙牙合平面：由连接上颌第2前磨牙颊尖和上颌第2磨牙或第3磨牙(如果萌出)颊尖的假想平面。 背景：研究表明颅底角与矢状骨面型的形成有关，牙合平面或后牙牙合平面对矢状骨面型形成的影响也存在一定的争议。 目的：比较牙合平面倾斜度与后牙牙合平面倾斜度在决定矢状骨面型形成中的重要性，探讨颅底曲度、后牙牙合平面倾斜度对矢状骨面型形成的综合效应，及两者之间的相关性。 方法：研究方案的实施符合西南医科大学附属口腔医院的相关伦理要求，患者及监护人对测量过程均知情同意，并签署了知情同意书。选择符合纳入标准的207名个体的头颅侧位片(男100例，女107例，年龄12-20岁)，利用Uceph 软件、SPSS软件(版本17.0)进行相关指标的测量和分析。按照前后不调指数(APDI)值将样本的矢状骨面型分为3组：Ⅱ类组、Ⅰ类组、Ⅲ类组。SNK、LSD 法比较各项相关指标在3组之间的差异。运用Pearson积矩相关系数分析法对颅底角(NSBa角)、牙合平面(FH-OP)、后牙牙合平面(FH-POP)与其他相关测量指标的相关性进行分析。根据牙合平面倾斜度、后牙牙合平面倾斜度及颅底角进行分组，并运用成组t检验法分别对相关骨性与牙性指标的进行比较。根据后牙牙合平面角度和颅底角度建立4个牙齿骨骼型组：小颅底角-平坦后牙合平面组(S-F)，小颅底角-陡峭后牙合平面组(S-S)，大颅底角-平坦后牙合平面组(L-F)，大颅底角-陡峭后牙合平面组(L-S)。应用交叉单因素方差分析法进行各组间差异的比较。 结果与结论：①Ⅲ类错牙合畸形患者的颅底角明显小于Ⅰ类和Ⅱ类，而Ⅱ类错牙合患者的后牙牙合平面明显大于Ⅲ类和Ⅰ类；②代表矢状骨面型分类的指标(APDI及ANB角)在牙合平面倾斜组之间并未发现差异；③颅底角和后牙牙合平面交叉分组的比较中，只有小颅底角-平坦后牙牙合平面组和大颅底角-陡峭后牙牙合平面组间的比较结果显示ANB角和APDI值存在显著差异；④结果说明，对于影响矢状骨面型的形成的因素中，后牙合平面比牙合平面更具代表性；颅底角度和牙合平面倾斜度作为单独的指标在确立前后骨骼畸形方面存在局限性；颅底曲度和后牙合平面倾斜共同影响矢状骨面型的形成；在矢状骨面型形成过程中，颅底曲度及后牙合平面之间可能存在一定的补偿机制。 ORCID: 0000-0002-1930-6566(余星月)；0000-0002-2386-6515(程钎) 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     

Vascular endothelial growth factor-B is neuroprotective in an in vivo rat model of Parkinson's disease

Occlusal disharmony induced by placing an acryl cap on the lower incisors of rats is perceived as chronic stress. This chronic stress activates corticotropin-releasing hormone (CRH) neurons in the hypothalamic paraventricular nucleus (PVN), resulting in stimulation of the hypothalamic-pituitary-adrenal (HPA) axis. The ventral ascending noradrenergic bundles (V-NAB) from the brainstem innervate the PVN. To investigate the relationship between the response of the HPA axis and the V-NAB, we examined changes in extracellular noradrenaline (NA) in the PVN and plasma corticosterone, the final output of the HPA axis, following occlusal disharmony in rats injected with 6-hydroxydopamine (6-OHDA), a specific catecholamine neurotoxin. 6-OHDA microinjection into the V-NAB reduced the magnitude of the responses of extracellular NA in the PVN and the plasma corticosterone to occlusal disharmony. Our results suggest that V-NAB to the PVN are involved in occlusal disharmony-induced activation of the HPA axis.     

Geometric Morphometric Methods for Bone Reconstruction: The Mandibular Condylar Process of Pico della Mirandola

The issue of reconstructing lost or deformed bone presents an equal challenge in the fields of paleoanthropology, bioarchaeology, forensics, and medicine. Particularly, within the disciplines of orthodontics and surgery, the main goal of reconstruction is to restore or create ex novo the proper form and function. The reconstruction of the mandibular condyle requires restoration of articulation, occlusion, and mastication from the functional side as well as the correct shape of the mandible from the esthetic point of view. Meeting all these demands is still problematic for surgeons. It is unfortunate that the collaboration between anthropologists and medical professionals is still limited. Nowadays, geometric morphometric methods (GMM) are routinely applied in shape analysis and increasingly in the reconstruction of missing data in skeletal material in paleoanthropology. Together with methods for three‐dimensional (3D) digital model construction and reverse engineering, these methods could prove to be useful in surgical fields for virtual planning of operations and the production of customized biocompatible scaffolds. In this contribution, we have reconstructed the missing left condylar process of the mandible belonging to a famous Italian humanist of the 15th century, Pico della Mirandola (1463–1494) by means of 3D digital models and GMM, having first compared two methods (a simple reflection of the opposite side and the mathematical–statistical GMM approach) in a complete human mandible on which loss of the left condyle was virtually simulated. Finally, stereolithographic models of Pico's skull were prototyped providing the physical assembly of the bony skull structures with a high fitting accuracy. Anat Rec, 292:1088–1097, 2009. © 2009 Wiley‐Liss, Inc.     

改良数字化再定位导板和咬合导板辅助Le Fort Ⅰ型截骨上颌骨精准定位

背景:上颌骨Le FortⅠ型截骨是矫正上颌骨畸形及与颅骨位置关系异常最常见的手术方法,以往采用传统模型外科进行手术设计及手工制作咬合板的方法,人为操作误差大,难以精准地实施手术设计方案。近年来3D打印数字化定位导板在正颌外科中的应用显著提高了手术操作的精准度。目的:探讨改良数字化定位导板在上颌骨Le FortⅠ型截骨中的应用效果。方法:选择20例因上颌骨发育异常行上颌骨LeFortⅠ型截骨的患者,术前行薄层颅颌面CT扫描,将CT数据导入Mimics 20.0软件建立数字化模型,并进行虚拟手术设计。同时设计打印出改良数字化上颌骨截骨导板、上颌骨再定位导板和咬合定位导板,术中联合应用3种导板行上颌骨的截骨及再定位。术后1周复查颅颌面CT并进行设计方案的术后验证。结果与结论:①上颌骨模拟位置和术后实际位置距离偏差中位数的绝对值小于1 mm,牙合平面角度偏差中位数的绝对值小于1°;②图像融合偏差分析中,均方根值=(0.789±0.275)mm,其均数小于1 mm;③提示应用改良数字化上颌骨截骨导板、上颌骨再定位导板及咬合定位导板能够安全、便捷、精准地完成上颌骨Le FortⅠ截骨。     

三种改良人工牙修复全口义齿的稳定性及应力支撑

背景：改良牙合型是重度吸收牙槽嵴全口义齿修复的一种良好选择,其中线性牙合、舌向集中牙合及长正中牙合具有代表性。 目的：概述线性牙合、舌向集中牙合及长正中牙合3种改良牙合型的特点及其在全口义齿修复中的应用。 方法：计算机检索中国知识资源总库(中国期刊网)1985年1月至2011年11月、PubMed 数据库1965年1月至2011年11月与线性牙合型、舌向集中牙合型、长正中牙合型3种改良牙合型在全口义齿应用相关的文章。 结果与结论：线性牙合为单颌刃状牙一维接触,能尽可能减小侧向牙合力消除牙合干扰。舌向集中牙合比平面牙合美观,对于重度吸收牙槽嵴患者较解剖牙合型更稳定。长正中牙合型能满足患者长正中量的自然要求,以及无牙颌患者正中关系位至肌力闭合道终点位置之间无障碍的义齿设计要求。3种改良牙合型均能减小侧向牙合力,将牙合力集中于剩余牙槽嵴,有助于提高义齿稳定性和软硬组织的支持作用。     

不良咬合与颞下颌关节紊乱综合症发病的生物力学分析

本文通过对收集的存在不同类型咬合障碍的颞下颌关节紊乱综合征病人进行统计学分析，得出病理性合垂直距离减小对颞下颌关节的损害是最大的，从生物力学角度分析，不论单侧或双侧合垂直距离减小，咀嚼运动时，对双侧颌关节的损害都是存在的。     

Functional magnetic resonance imaging of brain activity during chewing and occlusion by natural teeth and occlusal splints

Brain imaging based on functional magnetic resonance (fMRI) is a useful tool for examination of neuronal networks and cerebral structures subserving visiospatial function. The purpose of this study was to compare the brain activity during chewing and occlusal function in centric occlusion on natural teeth or on occlusal splints. Four tasks were performed by 13 healthy, fully dentate subjects (21-32 years old, 6 female and 7 male): occlusal tap-tap movements in centric occlusion by natural teeth, after application of a maxillary occlusal splint and chewing movements on left and right sided rubberdam strips. In order to reveal which areas of the brain were more strongly activated, conjunction analyses between the different tasks were performed for each subject and for the average values of brain signal activity of all subjects. Whilst several known foci of activity were subtracted, differences of significant activity rested in areas of the sensorimotor cortex. Mainly ipsitaterality of hemispheres concerned the left and right sided chewing, whereas the conjunction between tap-tap movements on natural teeth and splint occlusion indicated only one weak, but significant activation foci. The study confirms fMRT as one of the most useful developing methods to clear up neuro-cortical effectiveness of occlusion and occlusal therapy.     

上颌前牙区不同种植修复体在不同咬合受力下的三维有限元分析

文题释义：口腔种植修复体：是一种以植入骨组织内的结构为基础来支持、固位上部牙修复体的缺牙修复方式,它包括种植体、固位螺丝、修复基台及上部修复体,故以上各结构良好的生物力学性能决定着种植修复体的长期稳定性。 三维有限元分析：通过单元格划分将连续的模型划分为有限个单元,后期根据研究的需要赋予其不同的材料性能,模拟生物力学环境,计算其所受应力。自1980年运用于口腔医学研究以来,有限元法已涉口腔种植的各个领域,如通过三维有限元法分析螺纹形态、基台角度、植体类型、颈部设计等因素对种植修复体的影响,目前经过国内外学者的大量研究,三维有限元模型的精确度也已得到了较大提升。 背景：在口腔种植修复治疗中,修复因素与咬合因素影响着植体内部结构及植体-骨界面处应力的分布,植体内部结构及植体-骨界面处应力分布是否平衡决定着种植体的长期寿命与周围骨质水平的稳定性。 目的：探讨与分析二氧化锆全瓷冠与钴铬合金烤瓷冠修复体在3种咬合关系中对植体-骨界面处、种植体、修复基台、固位螺丝及修复体内部应力分布的影响。 方法：参照1例上颌中切牙区行种植体植入修复患者的锥形束CT影像资料,运用Mimics17.0软件建立上颌中切牙种植修复体模型,分别构建二氧化锆全瓷冠与钴铬合金烤瓷冠两种三维有限元模型,模拟对刃合、正常合、深覆合3种咬合状况进行加载,分析在2种修复体与3种加载方式影响下种植体内部各结构与种植体-骨界面的应力分布情况。 结果与结论：①在钴铬合金烤瓷冠组中,当咬合关系由对刃合转变为正常合及深覆合时,修复体咬合位点处应力相应增加,而修复基台、种植体边缘及植体-骨界面处的应力减小;正常咬合关系中固位螺丝处的应力较其他两种咬合方式更为集中,等效应力峰值更高。②在二氧化锆全瓷冠组中,当咬合关系由对刃合转变为正常合及深覆合时,修复基台、种植体及种植体-骨界面的应力峰值呈逐渐下降趋势;正常合时修复体咬合位点及固位螺丝处的应力峰值高于其他两种咬合关系。③对刃合时,钴铬合金烤瓷冠组修复体咬合位点处的等效应力峰值略高于二氧化锆全瓷冠组,修复基台、固位螺丝、种植体与种植体-骨界面的等效应力峰值略低于二氧化锆全瓷冠组;正常合时,钴铬合金烤瓷冠组种植体颈部处的等效应力峰值略高于二氧化锆全瓷冠组,修复体、修复基台、固位螺丝、种植体-骨界面的等效应力峰值略低于二氧化锆全瓷冠组;深覆合时,钴铬合金烤瓷冠组修复体咬合位点处及种植体颈部处的等效应力峰值均高于二氧化锆全瓷冠组,修复基台、固位螺丝、种植体-骨界面的等效应力峰值略低于二氧化锆全瓷冠组。④结果表明,咬合关系与上部修复体的不同影响着应力在种植修复体各结构及植体-骨界面的分布,此结论或许能为种植修复体远期并发症的预测提供参考依据。 ORCID: 0000-0001-8522-5337(安尼卡尔•安尼瓦尔) 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

Effect of bite-raised condition on the hippocampal cholinergic system of aged SAMP8 mice

Occlusal disharmony induces chronic stress, which results in learning deficits in association with the morphologic changes in the hippocampus, e.g., neuronal degeneration and increased hypertrophied glial fibrillary acidic protein-positive cells. To investigate the mechanisms underlying impaired hippocampal function resulting from occlusal disharmony, we examined the effects of the bite-raised condition on the septohippocampal cholinergic system by assessing acetylcholine release in the hippocampus and choline acetyltransferase immunoreactivity in the medial septal nucleus in aged SAMP8 mice that underwent the bite raising procedure. Aged bite-raised mice showed decreased acetylcholine release in the hippocampus and a reduced number of choline acetyltransferase-immunopositive neurons in the medial septal nucleus compared to age-matched control mice. These findings suggest that the bite-raised condition in aged SAMP8 mice enhances the age-related decline in the septohippocampal cholinergic system, leading to impaired learning.     

Occlusal disharmony increases stress response in rats

Repeated or chronic stress is known to produce structural and functional changes in the rat brain, and in particular, alter the response of the hypothalamic–pituitary–adrenal (HPA) axis to subsequent new stress. Occlusal disharmony via placement of acryl cap on the lower incisors of rats is perceived as chronic stress. To determine the response of the HPA axis to subsequent new stress in rats with occlusal disharmony, we measured plasma corticosterone levels in these rats after subjecting them to new stress. Plasma corticosterone levels in rats with and without incisal cap increased and reached a peak 30 min after exposure to the new stress. However, a later decrease in plasma corticosterone levels from peak levels was found in rats with incisal cap compared with rats without incisal cap. This finding suggests that occlusal disharmony alters the response of the HPA axis to subsequent new stress.     

基于三维数字化建模的全口义齿咬合接触的计算机仿真

针对目前在口腔颌面修复领域对全口义齿咬合接触的研究中存在的问题,本文应用空间机构理论中的方向余弦矩阵法,建立Hanau(牙合)架的下颌运动位移矩阵,以Matlab6.5、VC6.0 及VTK为开发平台,通过应用激光扫描测量法,采用计算机图形学及数据库技术,重建人工牙列的三维数字模型,并测量标志点三维几何坐标数据,然后在此基础上,开发了运行于PC机上的全口义齿咬合接触计算机仿真软件系统.该系统能从任何需要的角度和位置清晰地全面观察Hanau(牙合)架上下颌咬合接触的全过程,并对咬合接触的位置和区域进行检测.该系统的实现将有助于深入分析全口义齿动态咬合接触的情况,并辅助医生作全口义齿修复工作的临床诊断.     

Occlusal Development and Masseter Activity in Alpacas (Lama pacos)

Tooth eruption and the development of occlusion are significant ontogenetic changes in the masticatory apparatus of mammals. Here, we test the hypothesis that changes in masseter activity are correlated with increased occlusal contacts at major stages of dental development in the alpaca, Lama pacos. We compare electromyographic data from the superficial and deep masseter in infant and juvenile alpacas prior to and following m1 occlusion and from adults with full permanent dentitions. The pre‐m1 and post‐m1 occlusion groups exhibit similar masseter activity durations, chewing cycle durations, and with the exception of the balancing‐side deep masseter, similar timing differences between the jaw muscles. On average, the balancing‐side deep masseter fires significantly later in the post‐m1 occlusion group. The m2–m3 group exhibits significantly longer chewing cycle length and an even later firing balancing‐side deep masseter. Increased occlusion is also associated with an increase in the relative amount of working‐side superficial and deep masseter muscle activity when compared with the balancing side muscles. Although the development of occlusal relations in infant and juvenile alpacas are associated with minor changes in masseter activation patterns, additional molar occlusal contacts increase chewing cycle duration resulting in concomitant changes in masseter recruitment patterns. Currently, we cannot rule out that musculoskeletal development influences masseter activity as demonstrated in other mammals. However, the data presented here indicate that alpacas have a relatively delayed onset of the adult motor pattern that may be correlated with changes in occlusal relations due to tooth eruption. Anat Rec, 2010. © 2009 Wiley‐Liss, Inc.     

数字人体断层彩色图像数据的真实感体绘制

目的　探索一种用于数字人体断层彩色图像数据的真实感三维重建方法。  方法　改进光线投射体绘制算法,将真实的颜色采样和传递函数颜色映射相结合,使其适应彩色数据;使用分割标记数据,为多重组织彩色数据分类,实现数字人体断层彩色图像的直接体绘制。  结果　此方法实现了数字人体复杂组织和器官的高度真实感三维重建。  结论　断层彩色图像数据的真实感体绘制,能准确反映数字人体结构的细节和颜色信息,得到边界清晰的三维模型。     

咬合接触对颞下颌关节生物力学影响的有限元研究

目的建立用于研究咬合接触与颞下颌关节生物力学关系的三维有限元模型,并设计不同的工况来分析不同咬合接触情况下颞下颌关节应力的变化规律。方法尸体头颅1具,平行于眶耳平面作CT扫描;取石膏模型,以三维扫描仪对牙列(牙合)面扫描;将石膏模型扫描参数与CT扫描参数换算到同一坐标系下,在髁突上方设均厚的类关节盘,关节盘顶及下颌角作约束设计,经划分网格生成有限元模型。工况一:左侧下颌不同牙位咬合接触面加载;工况二:在包括左侧下颌第二磨牙的颞下颌关节三维有限元模型上,设计下颌第二磨牙牙尖交错(牙合)、远中方向和颊侧方向三种加载部位的工况,研究不同工况下双侧髁突处应力分布变化的规律。结果(1)建立了包括双侧髁突、类关节盘及下颌牙列在内的用于分析咬合与颞下颌关节关系的三维有限元模型。(2)咬合加载牙位不同,双侧髁突应力效应不同,髁突外、中、前、顶等处为承受较高压强的区域。(3)咬合加载部位牙面承载形态不同,双侧髁突应力效应也不同,其变化包括应力性质和应力的分布特点等方面,远中加载和颊侧加载时分别可致加载侧髁突内极和加载对侧髁突内极应力集中。结论咬合接触部位及方向变化可影响髁突应力分布。     

MRI影像下股骨髁间窝三维数字化解剖学数据与实体解剖测量值的差异

背景：X射线、CT、MRI二维图像测量股骨髁间窝受投照体位、选取测量层面等影响,测量准确性较差。 目的：比较MRI影像下股骨髁间窝三维数字化模型测量值和尸体实体解剖测量值的差异,探讨基于MRI影像下三维数字化模型的准确性。 方法：对尸体膝关节标本行MRI扫描,将MRI图像导入Mimics软件对股骨髁间窝进行三维数字化重建,测量三维数字化髁间窝的相关解剖学数据,同时对尸体标本进行解剖,测量实体解剖学数据。 结果与结论：三维数字化重建髁间窝顶长度、髁间窝宽度、内外髁宽度、髁间窝指数测量值与实体解剖测量值差异无显著性意义(P > 0.05)。说明基于MRI影像下股骨髁间窝的三维数字化模型能够准确反映实体标本信息,可用于正常人股骨髁间窝的解剖学研究。