非贵金属材料钴铬合金烤瓷联冠及烤瓷桥修复后基牙咬合力与牙周组织的变化北大核心

背景:测量牙缺失患者修复后的咬合力指标,可有效判断修复效果和患者修复后口腔功能的恢复情况。目的:观察行钴铬合金烤瓷联冠、烤瓷桥修复后患者基牙咬合力及牙周组织的变化。方法:将100例男性烤瓷牙修复患者随机分5组修复,其中20例采用钴铬合金烤瓷联冠修复前牙,20例采用钴铬合金烤瓷联冠修复前磨牙,20例采用钴铬合金烤瓷联冠修复磨牙,20例采用钴铬合金烤瓷桥修复前牙,20例采用钴铬合金烤瓷桥修复后牙。修复前、修复后即刻、修复后6个月,检测基牙咬合力变化及牙周相关指标变化。结果与结论:(1)咬合力:5组修复后即刻、修复后6个月的咬合力均高于修复前(P<0.05);修复前、修复后即刻、修复后6个月,烤瓷联冠磨牙组、烤瓷桥后牙组的咬合力高于烤瓷联冠前磨牙组、烤瓷联冠前牙组、烤瓷桥前牙组(P<0.05),烤瓷联冠前磨牙组咬合力高于烤瓷联冠前牙组、烤瓷桥前牙组(P<0.05);(2)牙周组织:5组组内修复前后的牙周袋探诊深度、菌斑控制指数、临床附着水平、牙龈沟液量比较差异均无显著性意义(P>0.05);5组间各指标比较差异均无显著性意义;(3)结果表明:行钴铬合金烤瓷联冠、烤瓷桥修复治疗能显著提升患者基牙咬合力,并且对牙周影响很小,生物相容性较好。     

基于咬合动力学的磨牙点接触高副等效建模与评价

牙颌模型作为口颌系统与咀嚼机器人系统的代表性部件,其建模方式是影响此类多体系统动力学模型准确度的重要因素。本文以咀嚼机器人右侧第一磨牙为研究对象,提出一种由V型面与球面构成的点接触高副等效建模方式。首先,利用有限单元法对原始模型的3种静态接触工况(咬入接触、正中接触、咬出接触)与动态咀嚼工况进行咬合动力学分析,得到期望咬合力;其次,运用赫兹接触模型建立点接触高副等效模型静态接触工况的咬合力解析式,根据期望咬合力对解析式内法向量与咬合刚度等参数进行等效设计;最后,对等效模型在静态接触与动态咀嚼工况中的咬合力表现进行评价。本文结果表明,等效模型能够实现静态接触工况8项期望咬合力的等效,同时对动态咀嚼工况初期与末期咬合力变化吻合良好,中期引入一定程度的冲击,但可通过后续轨迹规划进行弱化。本文所提出的牙颌模型等效建模方案,进一步提升了多体系统动力学模型准确性,也为人体其他复杂接触的动力学建模提供了新思路。     

替牙期前牙反(牙合)患者治疗后口周力分布变化的研究

测量替牙期前牙反(牙合)患者治疗前后口周力的分布情况,为替牙期前牙反(牙合)的预防和临床治疗提供理论依据.临床选取30名替牙期前牙反(牙合)患者,年龄8岁～12岁,平均年龄10.8岁,其中男性15名,女性15名,测量其治疗前后姿势位时上、下中切牙区唇、舌侧,左右上、下第一前磨牙区颊舌侧,左右上、下第一磨牙区颊舌侧口周力值,分析姿势位时受试者牙弓周围口周力分布变化的情况及规律.治疗前后受试者口周力各区域的分布规律基本一致;值得注意的是治疗后下切牙舌侧不再存在负压现象;治疗前后上中切牙区口周力测量值存在着显著的差异(P＜0.05).口周肌肉等软组织具有适应硬组织改变的功能,随着硬组织结构的改变,口周软组织通过发生相应的变化来维持口颌系统原有平衡、稳定状态.     

三类骨性错牙合下颌牙弓和基骨弓的测量及相关性分析

目的探讨骨性错牙合与个别正常牙合下颌牙弓、基骨弓的形态差异及相关性。方法 27例骨性Ⅰ类错牙合、30例骨性Ⅱ类错牙合、20例骨性Ⅲ类错牙合及27例个别正常牙合于正畸治疗前进行锥形束CT扫描,获得下颌虚拟模型,分别测量牙弓、基骨弓的长、宽度,分析指标间的差异及相关性,并拟合牙弓、基骨弓的形态曲线。结果Ⅲ类错牙合的基骨弓长、宽度显著大于其余三组,牙弓宽度显著大于Ⅱ类错牙合,Ⅱ类错牙合的前牙牙弓长度显著大于其余三组。牙弓、基骨弓在尖牙间、磨牙间宽度及全牙段长度的相关系数r分别为0.818、0.836、0.818,前牙长度r为0.395。结论Ⅲ类错牙合基骨发育过度,Ⅱ类错牙合前牙弓最长以弥补其基骨发育不足;牙弓与基骨弓存在相关。     

咬合导板及颌间牵引钉技术在腓骨瓣修复下颌骨缺损中的应用北大核心

背景:上颌窦癌、软腭癌、扁桃体癌等恶性肿瘤手术及创伤等均可导致下颌骨缺损,下颌骨缺损患者咀嚼、吞咽、语音等功能障碍,且颜面部外观遭受影响。修复下颌骨缺损是颌面外科难题之一。目的:探讨咬合导板及颌间牵引钉技术在腓骨瓣修复下颌骨缺损中的应用价值。方法:纳入2014年6月至2015年12月在西南医科大学附属口腔医院应用游离腓骨瓣修复下颌骨缺损的患者75例,随机分为2组,试验组44例术中使用咬合导板和颌间牵引钉技术;对照组31例未采用咬合导板和颌间牵引钉技术,应用带钩牙弓夹板颌间牵引复位法。比较2组患者手术时间,供区、受区切口愈合情况,腓骨瓣成活率,面部外形,咬合关系,语音功能及并发症等多项指标。结果与结论:(1)试验组患者平均手术时间(9.1±1.7)h,对照组(10.2±2.1)h,2组差异有显著性意义(P<0.05);(2)试验组38例患者面部恢复对称,41例患者咬合关系正常/基本正常,39例患者语音功能正常/基本正常;对照组20例患者面部恢复对称,22例患者咬合关系正常/基本正常,21例患者语音功能正常/基本正常,以上差异均有显著性意义(P<0.05);(3)试验组患者的总并发症发生率及颌面部创口裂开率显著低于对照组(P<0.05),其余差异未见显著性意义;(4)结果表明,在腓骨瓣修复下颌骨缺损中应用咬合导板及颌间牵引钉技术简单有效,且并发症低。     

成人骨性错(牙合)的下前牙矢状向倾斜度和牙弓、基骨弓长度的比较及相关性分析

目的 比较骨性错(牙合)的下前牙矢状向倾斜度和牙弓、基骨弓长度，并评估3个指标间的相关性。方法 于治疗前收集104名骨性Ⅰ、Ⅱ、Ⅲ类错(牙合)及个别正常(牙合)的CBCT数据，使用MATLAB软件测量下前牙矢状向倾斜度和牙弓、基骨弓长度，分析指标间的差异及相关性。结果 Ⅲ类错(牙合)的下前牙矢状向倾斜度显著小于其余3组，牙弓、基骨弓长度大于其余3组；Ⅱ类错(牙合)的下切牙矢状向倾斜度显著大于其余3组。下前牙矢状向倾斜度与相应基骨弓长度呈中度负相关（中切牙区至尖牙区的相关系数r分别为-0.557、-0.554和-0.489,P<0.001），而与牙弓长度无相关性。结论 不同骨性错(牙合)的下前牙矢状向倾斜度和牙弓、基骨弓长度存在差异。通过下前牙矢状向倾斜度的大小可以评估相应基骨的矢状向发育情况，但改变下前牙矢状向倾斜度不足以影响牙弓长度。     

成人AngleII类错牙合软硬组织颅面结构特征：计算机X射线头影测量

背景：研究表明,覆盖在硬组织之上的软组织的厚度存在有较大的差异,不是均匀地覆盖在硬组织之上,即临床治疗错牙合畸形时,仅仅单纯进行硬组织测量将不能获得理想的侧貌外形。 目的：分析成人Angle II类错牙合软硬组织颅面结构特征,并分析Angle II1类与II2类软硬组织相关性。 方法：从2011至2014年佳木斯大学附属口腔医院正畸科门诊病例中选取成人Angle II类错牙合畸形患者60例,年龄在18-38岁之间,平均26.3岁,男女各半,其中Angle II1类和II2类各30例,采用计算机X射线头影测量技术对比分析Angle II1类和II2类错牙合畸形软硬组织测量项目的差异以及其软硬组织相关性。 结果与结论：①硬组织测量结果：两组患者SNB角(蝶鞍中心点、鼻根点及下齿槽座点所构成的角)、SND角(蝶鞍中心点、鼻根点及下颌联合部中心点所构成的角)、ANB角(上齿槽座点、鼻根点与下齿槽座点构成的角)、面角(FH-NP)、上中切牙角(U1-SN,P < 0.001)、LI-NB角(P < 0.01)、下中切牙角(L1-MP,P < 0.01)、上下中切牙角(U1-L1,P < 0.001)的差异有显著性意义(P < 0.05)。②软组织测量结果：两组患者上唇倾角(ULA’ -FH)、下唇突角(LLNs-FH)、上唇突角(ULNs-FH)、鼻唇角(CmSnUL)、下唇-审美平面距(E-LL)的差异有显著性意义(P < 0.05)。③两组患者软硬组织各测量项目间有相关,相关性高低存在差别。结果表明AngleII1类错牙合的上颌骨及上前牙的突度对下唇部的位置有一定的影响。而Angle II2类只有上颌突度对下唇部软组织的位置的影响。Angle II2类错牙合颏部软组织变异较小,而Angle II1类错牙合的颏部软组织变异较大。临床治疗成人Angle II类错牙合畸形患者制定方案时,需结合其各自的软硬组织结构特点进行正畸、正颌外科治疗以及方案的制定。     

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     

兰州地区成人正常牙合牙弓后段长度的差异

背景：牙弓后段长度不足与错牙合畸形的形成和发展密切相关。 目的：测量兰州地区成人个别正常牙合牙弓后段长度。 方法：在兰州地区甘肃籍在校大学生中选择18-24岁正常牙合102例(男47例,女55例),平均年龄(19.33±2.67)岁,拍摄头颅侧位片,按照下颌平面角分为高角组(>32°)、低角组(<22°)、均角组(22°-32°)3组。分别测量受试者上、下颌牙弓后段长度,并进行性别、组内、组间比较分析。 结果与结论：上颌牙弓后段长度男性稍大于女性,差异无显著性意义(P > 0.05)。下颌牙弓后段长度男性稍大于女性,差异无显著性意义(P > 0.05)。组间比较发现,男性低角型下颌牙弓后段长度显著大于男性高角型下颌牙弓后段长度,差异有显著性意义(P < 0.05)。可以初步说明牙弓后段在发育过程中不受性别影响,不同垂直骨面型、不同性别成人个别正常牙合牙弓后段长度存在差异。     

高角骨性Ⅲ类错牙合牙齿倾斜位置特征

目的　了解高角Ⅲ类错牙合 畸形患者全牙轴倾及转矩特征,以期为临床治疗提供指导。 方法　收集符合纳入标准的高角骨性I类（13名）及Ⅲ类（11名）错牙合 畸形共计24名患者头颅CBCT影像Dicom数据,利用invivo 5.1软件进行全牙轴倾度及转矩测量。 结果　（1）高角I类及Ⅲ类左右同名牙倾斜度一致性较好,P＞0.05,此后左右同名牙数据一并处理。（2）高角Ⅲ类与I类矢状向比较：①高角Ⅲ类,上前牙根舌向转矩增大趋势,但仅在上尖牙表现统计学差异,P＜0.05;②高角Ⅲ类,下前牙根舌向转矩减小,P<0.05,差异有统计学意义;③ 高角Ⅲ类,上后牙近中轴倾、下后牙远中轴倾趋势,但差异无统计学意义,P>0.05。（3）高角Ⅲ类与I类横向比较：①高角Ⅲ类,上前牙远中轴倾增加,差异有统计学意义;下前牙轴倾变化趋势不明,仅下中切牙表现远中轴倾（P<0.05）;② 高角Ⅲ类,上后牙根舌向转矩增大,有统计学差异;下后牙根舌向转矩减小趋势,但差异无统计学意义。（4） 高角I类及Ⅲ类与Andrews正常牙合 矢状向及冠状向各牙倾斜位置比较：① 矢状向：高角I类Ⅲ类上下前牙根舌向转矩增大,上下后牙明显近中倾斜;② 冠状向：高角I类Ⅲ类上下前牙远中倾斜增大,上下后牙根舌向转矩加大。 结论　（1）高角骨性Ⅲ类牙齿位置在垂直方向的代偿表现强于矢状方向;（2）高角骨性Ⅲ类上下前牙唇舌向倾斜移动风险较高,移动时更应注重牙齿的整体移动;（3）高角骨性Ⅲ类上颌后牙明显颊向倾斜,上牙列横向扩展范围减小,扩弓后稳定性可能降低。     

Change of Distribution and Timing of Bite Force after Botulinum Toxin Type A Injection Evaluated by a Computerized Occlusion Analysis System

Purpose

The aim of this study was to determine the force distribution and pattern of mastication after injection of botulinum toxin type A (BTX-A) into both masseter muscles. The hypothesis to be tested was that the difference between right and left balance of occlusal force diminishes over time following BTX-A injection.

Materials and Methods

Fifteen patients were submitted to BTX-A injection therapy for subjective masseter hypertrophy. A total of 25 U of BTX-A (50 U in total) was injected into two points located 1 cm apart at the center of the lower one-third of both masseter muscles. All patients were examined using the T-Scan occlusion analysis system before and 4, 8, 12, and 24 weeks after BTX-A injection.

Results

A significant change in force balance was found between the right and left sides over time and the difference between the two sides decreased with the time post-injection, reaching a minimum at 12 weeks. Comparison of the force balance between the anterior and posterior occlusions revealed no significant difference at any of the time points. The occlusion and disclusion times (right and left sides) did not differ significantly with time since BTX-A injection.

Conclusion

A decline in the difference in the clenching force between the left and right sides was found with increasing time up to 12 weeks following BTX-A injection.     

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.     

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.     

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.     

锥形束CT测量单侧后牙正锁牙合髁突的体积和表面积

背景：髁突是下颌骨的生长发育中心,不对称的咬合关系可能会导致其形态的变化。 目的：通过锥形束CT测量单侧后牙正锁牙合髁突体积和表面积,观察单侧后牙正锁牙合对髁突形态的影响。 方法：从重庆医科大学附属口腔正畸科就诊患者中选取29例成年单侧后牙正锁牙合患者为实验组,同期从门诊检查者中选取32例成年正常咬合为对照组,所有对象均无经正畸治疗史。拍摄锥束CT,用 Mimics 10.0软件对髁突影像进行三维重建。 结果与结论：实验组锁牙合侧髁突表面积和体积均大于非锁牙合侧(P < 0.05),实验组体积和表面积的不对称性指数明显大于对照组(P < 0.05)。结果证实,单侧后牙正锁牙合患者双侧髁突对称性较差。 关键词：锁牙合;锥形束CT;髁突;体积;表面积;数字化图像 doi:10.3969/j.issn.1673-8225.2012.13.018     

人牙咬痕形态学变化的生物力学研究

从生物力学角度研究人牙咬痕形态学变化的动态过程。以不同形态的牙和不同量的牙合力造成活体和死亡动物的咬痕 ,长时间动态追踪观察其变化过程 ,并测定相关形态参数 ,多元逐步回归分析咬痕形态与牙合力、时间、牙形态包括牙面积、牙宽度、牙厚度之间的关系 ,建立了咬痕形态学变化与多个力学、形态学因素的内在数学关系。     

糖尿病模型小鼠拔牙后对颌牙牙合向伸长过程中根周骨密度及相关因子的变化

文题释义： 抗酒石酸酸性磷酸酶：是破骨细胞的标志性酶，为酸性磷酸酶的同工酶，绝大多数来源于破骨细胞，特异性的分布于破骨细胞胞浆中，染色酶活性部位为紫红色，核为阴性，为绿色，颜色反差大，易区分，特异性强。骨连接蛋白：是一种非结构性的细胞外间质蛋白，分子质量较小，为高度进化的保守序列，基因位于人类第9号染色体，小鼠第11号染色体，由3个独立的区域组成：①末端酸性钙离子结合区域；②卵泡静止素同源的铜离子结合区域；③细胞外钙离子结合区域，其中最重要的功能是骨连接蛋白可以调节细胞外基质和基质金属蛋白酶的产生。 背景：牙列缺失是常见的口腔疾病，若得不到及时有效的治疗，就会出现邻牙倾斜、对颌牙伸长等不良影响，造成牙合紊乱以及牙合干扰，严重影响后期修复。尤其是糖尿病患者牙列缺失后，对颌牙在牙合向伸长过程中，糖尿病对其有何影响？骨连接蛋白在此过程如何变化？目前尚不清楚。 目的：通过建立糖尿病小鼠对颌牙牙合向伸长运动实验模型，研究糖尿病对小鼠牙齿牙合向伸长运动过程的影响。 方法：向C57 BL/6J小鼠(购买于山西医科大学动物实验中心)腹腔注射链脲佐菌素建立糖尿病模型，以腹腔注射柠檬酸钠缓冲液的小鼠为对照。取建模成功的糖尿病小鼠与对照组小鼠各30只，拔除右上颌3颗磨牙建立对颌牙牙合向伸长运动实验模型，术后0，3，6，9，12 d，取右侧下颌骨，利用Micro CT测量骨密度，抗酒石酸酸性磷酸酶染色计数破骨细胞数量，RT-qPCR检测骨连接蛋白基因的表达。实验方案经山西医科大学伦理委员会批准。 结果与结论：①随着时间的延长，两组右侧下颌骨的骨密度逐渐增加，糖尿病组术后3，6，9，12 d的骨密度低于对照组(P < 0.05)；②随着时间的延长，两组右侧下颌骨的破骨细胞数量逐渐增多，糖尿病组术后3，6，9，12 d的破骨细胞数量少于对照组(P < 0.05)；③随着时间的延长，两组右侧下颌骨的骨连接蛋白基因表达量逐渐升高，糖尿病组术后0，3，6，9，12 d的骨连接蛋白基因表达量高于对照组(P < 0.05)；④结果表明，糖尿病可降低牙齿牙合向伸长运动过程中的骨改建能力并提高骨连接蛋白基因表达。ORCID: 0000-0003-0898-6073(杨晓叶) 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     

Detailed Anatomical Orientations for Certain Types of Morphometric Measurements Can Be Determined Automatically With Geometric Algorithms

Morphometric datasets only convey useful information about variation when measurement landmarks and relevant anatomical axes are clearly defined. We propose that anatomical axes of 3D digital models of bones can be standardized prior to measurement using an algorithm that automatically finds a universal geometric alignment among sampled bones. As a case study, we use teeth of “prosimian” primates. In this sample, equivalent occlusal planes are determined automatically using the R‐package auto3dgm. The area of projection into the occlusal plane for each tooth is the measurement of interest. This area is used in computation of a shape metric called relief index (RFI), the natural log of the square root of crown area divided by the square root of occlusal plane projection area. We compare mean and variance parameters of area and RFI values computed from these automatically orientated tooth models with values computed from manually orientated tooth models. According to our results, the manual and automated approaches yield extremely similar mean and variance parameters. The only differences that plausibly modify interpretations of biological meaning slightly favor the automated treatment because a greater proportion of differences among subsamples in the automated treatment are correlated with dietary differences. We conclude that—at least for dental topographic metrics—automated alignment recovers a variance pattern that has meaning similar to previously published datasets based on manual data collection. Therefore, future applications of dental topography can take advantage of automatic alignment to increase objectivity and repeatability. Anat Rec, 298:1816–1823, 2015. © 2015 Wiley Periodicals, Inc.     

Surface Action Potential and Contractile Properties of the Human Triceps Surae Muscle: Effect of ''Dry'' Water Immersion

The effects of 7 days of "dry" water immersion were investigated in six subjects. Changes in the contraction properties were studied in the triceps surae muscle. After immersion, the maximal voluntary contraction (MVC) was reduced by 18.9 % (P < 0.01), and the electrically evoked (150 impulses s(-1)) maximal tension during tetanic contraction (P(o)) was reduced by 8.2 % (P > 0.05). The difference between P(o) and MVC expressed as a percentage of P(o) and referred to as force deficiency was also calculated. The force deficiency increased by 44.1 % (P < 0.001) after immersion. The decrease in P(o) was associated with increased maximal rates of tension development (7.2 %) and relaxation. The twitch time-to-peak was not significantly changed, and half-relaxation and total contraction time were decreased by 5.3 % and 2.8 %, respectively, but the twitch tension (P(t)) was not significantly changed and the P(t)/P(o) ratio was decreased by 8.7 %. The 60 s intermittent contractions (50 impulses s(-1)) decreased tetanic force to 57 % (P < 0.05) of initial values, but force reduction was not significantly different in the two fatigue-inducing tests: fatigue index (the mean loss of force of the last five contractions, expressed as a percentage of the mean value of the first five contractions) was 36.2 +/- 5.4 % vs. 38.6 +/- 2.8 %, respectively (P > 0.05). While identical force reduction was present in the two fatigue-inducing tests, it would appear that concomitant electrical failure was considerably different. Comparison of the electrical and mechanical alterations recorded during voluntary contractions, and in contractions evoked by electrical stimulation of the motor nerve, suggests that immersion not only modifies the peripheral processes associated with contraction, but also changes central and/or neural command of the contraction. At peripheral sites, it is proposed that the intracellular processes of contraction play a role in the contractile impairment recorded during immersion.     

Computer-aided determination of occlusal contact points for dental 3-D CAD

Present dental CAD systems enable us to design functional occlusal tooth surfaces which harmonize with the patient’s stomatognathic function. In order to avoid occlusal interferences during tooth excursions, currently available systems usually use the patient’s functional occlusal impressions for the design of occlusal contact points. Previous interfere-free design, however, has been done on a trial-and-error basis by using visual inspection. To improve this time-consuming procedure, this paper proposes a computer-aided system for assisting in the determination of the occlusal contact points by visualizing the appropriate regions of the opposing surface. The system can designate such regions from data of the opposing occlusal surfaces and their relative movements can be simulated by using a virtual articulator. Experiments for designing the crown of a lower first molar demonstrated that all contact points selected within the designated regions completely satisfied the required contact or separation during tooth excursions, confirming the effectiveness of our computer-aided procedure.