拇指对掌运动6个自由度的采集与分析

目的　利用Motion capture运动捕捉及分析系统获得拇指对掌过程的6个自由度,尝试建立手功能检测的数字化方法。 方法 1例外形及功能均正常成人手, 在手掌背侧及各指皮肤上粘贴直径为5 mm荧光标志球。分别使拇指在自由状态、掌指关节、指间关节、掌指及指间关节固定,拇指与 2~5 指做最大范围对指运动,Motion capture运动捕捉及分析系统采集对掌运动的6个自由度,并对其6个自由度进行分析。 结果 Motion capture运动捕捉及分析系统获得了拇指对掌运动的6个自由度。通过统计描述分析,在拇指的掌指与指间关节未固定状态的对掌运动中,拇指与其余4指的对掌运动,线位移最大变化主要发生Y轴,角位移最大变化主要发生Z轴,同时其它2个轴的位移也发生相应变化。拇指在掌指与指间关节不同的固定状态下,线位移及角位移均有灵敏变化。 结论 Motion capture运动捕捉及分析系统能够采集拇指对掌的6个自由度,并可以明确拇指对掌运动过程的数字化规律,为建立以6 个自由度为基础手功能检查方法奠定了基础。     

下颌螺旋轴轨迹的三维显示和分析系统的开发

本研究拟开发下颌螺旋轴轨迹的三维显示和分析系统,用于定量分析下颌的三维空间运动。采用6自由度的超声下颌运动记录仪测量下颌运动;利用计算机断层扫描图像重建上颌、下颌颅骨的三维数字模型;通过结构光三维扫描仪将颅骨的三维数字模型校准至下颌运动数据的坐标系。基于Visualization ToolKit和Open Scene Graphics Library开发了本系统,利用下颌运动数据计算连续变换矩阵来仿真下颌运动,通过特征值方法计算下颌的螺旋轴轨迹,并实时显示螺旋轴轨迹与下颌的空间位置关系。本系统可以计算并输出下颌螺旋轴的参数(旋转、平移、方向、位置),用于精确评价下颌的三维空间运动。因此,本系统为采用螺旋轴理论研究下颌的三维空间运动奠定了一定的理论依据和实验基础。     

无症状颞下颌关节盘前移位个体的动态磁共振及髁突运动轨迹特点

目的 颞下颌关节盘早期的前移位临床上可无弹响症状,了解无症状颞下颌关节盘的早期移位个体的髁突运动中心轨迹特点,将有助于早期发现隐匿性颞下颌关节结构内紊乱疾病。 方法 动态磁共振(Cine-MRI) 和ARCUSdigma系统检查30例无症状个体开闭口过程中髁状突-关节盘运动特点和下颌运动范围。 结果 Cine-MRI显示30例无症状人群中,20例健康颞下颌关节、10例单侧可复性关节盘前移位,闭口位关节盘本体部仍呈双凹形、盘后区均有轻度增厚和前移位,盘-突关系在小开口（<2 cm）期恢复正常;无症状可复性关节盘的运动中心轨迹出现弹跳切迹和偏摆,光滑性、重复性及双侧运动中心轨迹的对称性不及健康人,但是切点运动轨迹平滑,与健康人的切点运动轨迹基本一致;运动轴在髁突轨迹弹跳时出现偏斜,然后保持平行,呈现开闭口初、末时密度比开闭口中时大;髁突运动中心运动距离（13.6±3.7）mm,下颌切点运动距离（40.5±3.4）mm。 结论 髁突运动轨迹能间接反映髁突-关节盘复合体在开闭口运动中的位置变化,为下一步临床使用下颌运动轨迹仪作为早期关节盘移位的诊断提供一定的理论参考。     

基于激光扫描与CT建立带牙根的三维数字化牙颌模型

目的　基于激光三维扫描牙颌模型,结合临床头部CT资料,建立包含牙根的数字化牙颌模型,记录牙冠和牙根解剖形态结构以及空间位置变化。 方法　1例牙列正常成年女性,头部CT数据利用Mimics11.0软件建立口腔内单独牙齿和整个上下牙列三维数字化模型;三维激光扫描仪分别扫描上下颌石膏模型及其咬合关系,在GeoMagic10.0软件中,结合CT重建的单独牙齿的三维数字化模型,重构带有牙根的牙列三维模型,同时实现上下颌三维模型符合口腔实际咬合关系的位置恢复。 结果　重建了带有牙根的三维数字化上下颌牙列模型,不仅清晰显示牙冠的解剖特征、牙列的排列、牙根的形态和位置关系,并且准确恢复了上下颌牙列的咬合关系。 结论　在正畸治疗过程中,利用激光三维扫描及CT数据建立带有牙根的三维数字化牙颌模型,不仅可以显示牙冠牙根的解剖形态结构,还能够监测牙冠和牙根的移动情况,便于指导治疗进程,评价治疗效果。     

下颌骨数字化可视模型的建立

目的:建立下颌骨的三维数字化可视模型。方法:选择合适的尸体标本,经固定、动脉灌注、冷冻、包埋、洗切、数据采集,获得数字人数据集,取数字人数据图像中下颌骨有关的二维图像,提取其轮廓线,利用Amira软件系统进行下颌骨的外形及下颌管的重建。结果:利用数字人数据得到下颌骨精细的三维模型,在三维空间上真实地再现了下颌骨、下颌牙的解剖形态,并准确地显示出下颌管的位置与走行。结论:通过数字人数据,采用应用软件重建方法获得下颌骨三维模型,为口腔解剖及外科教学、下颌骨的美容整形及正颌外科手术治疗、下颌牙齿种植等提供了解剖学依据。     

下颌骨缺损钛重建板修复的生物力学分析

背景:钛重建板是重建下颌骨最常用金属材料,术后钛重建板断裂和钛钉松动最终导致手术的失败。研究分析,钛重建板断裂的钛钉松动的原因很多,包括钛钉的完全承载,余留牙的咬合力过大,钛重建板长度过长,钛钉数量过少,手术中预弯机械损伤等。目的:首次建立正常下颌骨和下颌骨缺损钛重建板重建的三维有限元模型,并对其生物进行力学分析。方法:选择一名咬牙合关系正常的成年男性为志愿者,对其下颌骨进行多层螺旋CT扫描,获得原始数据。基于CT扫描图像原始数据,利用高性能电子计算机及逆向工程软件Mimics建立正常下颌骨及钛重建板重建下颌骨三维模型及三维有限元模型,模拟垂直和斜向咬牙合状态下,正常下颌骨及钛重建板重建下颌骨应力分布情况。结果与结论:①获得了三维有限元模型:正常下颌骨由80044个节点,431899个单元组成;下颌骨缺损(SS型)钛重建板重建下颌骨由68400个节点和247379个单元组成。②正常下颌骨在后牙垂直咬牙合下vonMises应力较大区域分布在下颌升支前缘20.15MPa、下颌角19.45MPa和髁颈部15.35MPa。钛重建板重建下颌骨模型的应力分布,垂直咬牙合状态下,升支前缘vonMises应力最大值19.34MPa,髁颈部10.21MPa,下颌角18.56MPa,钛重建板中部24.58MPa,钛钉18.35MPa。模拟斜向45°咬牙合状态下vonMises应力分布最大值,钛重建板重建下颌骨右侧髁颈部升支前缘19.34MPa,右侧髁颈部10.21MPa,下颌角18.56MPa,钛重建板24.58MPa,钛钉18.35MPa。结果说明钛重建板重建下颌骨应力分布,明显集中于钛重建板,钛钉,与正常对比应力分布不均匀,因此影响下颌骨缺损钛重建板重建的牢固性。     

Hanau(牙合)架下颌侧方运动的数学模型

针对目前下颌运动的研究大多集中在生理学方面的不足,我们从空间机构运动理论的角度出发,对Hanau架运动链自由度进行分析并提出约束条件假设,以空间解析几何建立描述Hanau架下颌三维侧向空间运动的数学模型,通过在Matlab6.5及VC 6.0环境下编制软件程序求解,得到其任意点的运动轨迹,从而验证了髁导斜度及切导斜度与定位平面斜度成正变关系,对Hanau提出的5因素10定律提供了理论依据。该数学模型的建立将有助于深入分析下颌运动过程中上下颌的动态咬合,从而达到最终实现以虚拟架替代机械架的目的。     

不同训练方案对下颌骨单侧髁突骨折患者术后开口度训练效果的影响

目的观察不同训练方案对下颌骨单侧髁突骨折患者术后开口度训练效果的影响。方法选取我院收治的80例行手术治疗的下颌骨单侧髁突骨折患者,依据术后训练方案分为对照组(n=36)与干预组(n=44),对照组给予常规康复训练,干预组给予下颌运动康复训练,比较2组患者术前、术后1个月、术后6个月下颌主动张口度、健侧活动度、患侧活动度及前后活动度,观察2组患者术后6个月张口受限、咬合关系紊乱情况。结果干预组术后1个月与术后6个月下颌主动张口度、下颌健侧活动度、下颌前后活动度大于对照组,差异有统计学意义(P<0.05);术后6个月时,干预组张口受限率与咬合关系紊乱率低于对照组,差异有统计学意义(P<0.05)。结论相较于常规康复训练,下颌运动康复训练方案对下颌骨单侧髁突骨折患者手术后开口度与活动度的训练效果更好,可缩短下颌运动功能恢复进程,减少张口受限及咬合关系紊乱。     

虚拟咬合运动初步仿真模拟的研究与实现

我们试验了利用VR技术进行虚拟咬合仿真制作的全部过程。首先,采用光学三维测量仪对上下颌石膏模型进行数字化,通过预处理获取有效的三角网格曲面模型;其次,对咬合运动模型进行合理的简化,分解为一系列的平移运动和旋转运动;通过动态刷新完成开闭口运动、侧移运动的计算机运动仿真,可视化地观察咬合运动;然后利用模型碰撞检测算法动态地计算咬合接触位,并详细地分析了咬合接触时的咬合点位置分布和咬合剖切面上的咬合点接触关系;最后讨论了目前虚拟咬合仿真存在的问题和今后研究的方向。     

下颌骨缺损腓骨瓣修复不同固定方式的有限元分析

背景:肿瘤、外伤等原因常常造成下颌骨节段性缺损,血管化腓骨瓣同期重建下颌骨缺损是目前最主要的修复方式。目前在临床上既有用重建钛板进行固定,又有用小型钛板固定,有临床回顾性研究表明重建钛板和小型钛板固定方式患者术后并发症率无明显差异,但目前仍缺少固定稳定性相关的生物力学研究。目的:试验用三维有限元法分析下颌骨节段性缺损腓骨瓣修复时用重建钛板和小型钛板固定后的应力分布和稳定性。方法:选择1例牙列完整的成年男性进行CT扫描,并将数据录入计算机之后重建下颌骨及牙列模型,根据下颌骨缺损的Jewer分类,建立H(一侧下颌体、下颌角、下颌升支和髁突的缺失),L(一侧下颌体缺失)和C(双侧下颌骨颏部缺失)3类缺损三维模型,利用三维有限元分析法,对这3种下颌骨缺损腓骨修复后重建板和小型板固定的力学分布特点和稳定性进行对比研究。结果与结论:①从应力云图可以大致判断,正常下颌骨应力较大值主要发生在髁突、髁颈、下颌角、磨牙、钛板钛钉等周围区域处,尤其以下颌角附近处应力最大;②H类缺损在重建钛板修复下颌骨时将对下颌角附近产生较大应力,局部应力集中达185MPa,在H类小型钛板、L类小型钛板及重建钛板修复条件下,钛板的应力为117-135 MPa,腓骨块的应力最大值基本在30.4 MPa以下,钛钉应力最大值为56.2 MPa;③H及L类缺损小型钛板、重建钛板修复后骨断端相对位移变化为15-18μm,C类缺损下颌骨钛板修复后骨断端基本不产生相对位移;④结果证实,重建钛板和小型钛板均能满足这3种缺损腓骨修复的生物力学要求。     

Spatiotemporal consistency of human mandibular and head-neck movement trajectories during jaw opening-closing tasks

Previous studies of spatial and temporal coordination between human mandibular and head-neck movements during single as well as rhythmic jaw opening-closing tasks suggest that these movements are regulated by central nervous commands common for jaw and neck muscles. The present study evaluated the spatiotemporal consistency of concomitant mandibular and head-neck movements during repeated single jaw opening-closing tasks, in short- as well as long-term perspectives and at different speeds. The subjects were seated in an upright position without head support. They were instructed to perform single maximal jaw opening-closing movements, repeated ten times for fast and slow speed, respectively. Recordings were made at two sessions. A wireless optoelectronic technique was used to record three-dimensional mandibular and head-neck movements. The spatiotemporal consistency of repeated movement trajectories of the mandible (both in relation to the head and in space) and of the head-neck was quantitatively assessed by a spatiotemporal index (STI). In addition, mean movement trajectory patterns were compared for speed and recording sessions (expressed as correlation coefficient, r). The results showed relatively small STI (high degree of spatiotemporal consistency) and high r (reproducible trajectory patterns) values, both in short- and long-term perspectives, for concomitant mandibular and head-neck movements. The data were not generally speed related. In conclusion, the present results suggest a high degree of spatiotemporal consistency of the kinematic patterns of mandibular and head-neck movements during jaw opening-closing, in short- as well as long-term perspectives. They also indicate that underlying neural processes are invariant in nature. The results give further support to the notion of a tight functional coupling between the human jaw and the neck motor systems during natural jaw function.     

成人牙根唇舌侧牙槽骨的厚度

背景：牙根在牙槽骨的位置及周围骨板厚度影响着口腔治疗,治疗过程中如果对牙齿控制不当可造成医源性并发症。以往对颌骨的研究主要针对解剖学、骨厚度或骨密度,对于牙根在牙槽骨内的空间位置及其与周围骨骼的关系,研究关注较少。 目的：建立颌骨的数字化计算机三维模型,测量牙根的唇舌侧牙槽骨厚度。 方法：选择牙列完整无明显骨骼吸收的年轻成人70例,采用牙科专用锥形束CT机进行颌面部扫描,将扫描中采集的容积信息传入计算机工作站,以及冠状位或矢状位多平面重建,获得高质量的重建图像,原始数据以DICOM格式导入计算机,并输出到整合的3D设计软件Invivo5软件进行测量。 结果与结论：重建的颌骨数字化模型可从多平面进行观察及测量,实验测得70 例患者各个牙根唇舌侧牙槽骨厚度的均值：上下前牙舌侧牙槽骨厚度大于唇侧(P < 0.05);除上前磨牙的牙颈部唇侧牙槽骨较厚外, 其他前磨牙舌侧牙槽骨厚度大于唇侧(P < 0.05);上磨牙和下颌第一磨牙唇舌侧牙槽骨厚度接近,下第二磨牙唇侧牙槽骨厚度大于舌侧(P < 0.01)。结果证实,成人不同牙位的唇舌侧牙槽骨厚度差异较大。     

Development of a three-dimensional jaw-tracking system implanted in the freely moving mouse.

A high-resolution mandibular tracking system was designed and tested in a freely moving mouse. A sensor unit, which consisted of four small magnetic sensors, was employed to trace small magnet movements in the three-dimensional space. After the sensor's output-to-displacement transformation equations were obtained from a multiple regression analysis of pre-experimental calibration data, the magnet and the sensors were transferred to the mouse, being kept at the same configuration as determined in the calibration system. In order to measure the three-dimensional jaw movements, the magnet was glued on the mandibular surface of the mouse and the sensor unit was implanted in the nasal bone. Jaw-movement trajectories were obtained as electrical signals from the sensors after being compensated by the output-to-displacement transformation equations of the sensors with a personal computer. This sensor system, applied to the freely moving mouse, could trace the jaw trajectories with an accuracy of better than 20 microm in three-dimensional space. Consequently, the typical pattern of the rhythmical jaw movements of the mouse during mastication was obtained. The mouse protruded the mandible to the most anterior position in the jaw-opening phase and retruded to it the most posterior position in the jaw-closing phase.This tracking system may also be applied to other small animals.     

Comparison of mandibular movement trajectories and associated patterns of oral muscle electromyographic activity during spontaneous and apomorphine-induced rhythmic jaw movements in the guinea pig

Vertical and horizontal movements of the lower jaw (mandible) of ketamine-anesthetized guinea pigs were recorded in association with electromyographic (EMG) activity in the anterior digastric, lateral pterygoid, medial pterygoid, and deep masseter muscles during spontaneously occurring rhythmic jaw movements (SRJMs) and during rhythmical jaw movements induced by the intravenous administration of apomorphine (ARJMs). Both ARJMs and SRJMs were near periodic and occurred at frequencies in the 2- to 5-Hz range. However, the profiles of the mandibular movements and associated patterns of jaw muscle EMG activity differed dramatically for SRJMs versus ARJMs. SRJMs were characterized by prominent lateral excursions of the mandible that occurred in association with both the jaw opening and closing movements. The lateral excursions were directed to the left side on some SRJM cycles and to the right side on others. The direction of the lateral component alternated irregularly, but no more than three consecutive cycles with horizontal movements to the same side were observed at any time. Each SRJM cycle was generated by the occurrence of one of two coordinated sequences of EMG activity. One sequence produced right-sided cycles, the other produced left-sided cycles. Each sequence was initiated by an EMG burst in the digastric muscle ipsilateral to the direction of the horizontal excursion of the mandible, followed by EMG bursts in the contralateral digastric, lateral pterygoid, and medial pterygoid muscles. The EMG bursts in the digastrics and contralateral lateral pterygoid muscles were associated with jaw opening and the initial stage of lateral movement. EMG activity in the contralateral medial pterygoid muscle was associated with the onset of closing and a second stage of lateral movement. Masseter muscle activity was also observed during SRJMs, but only in a subset of the animals tested (3 of 12). When present, the masseter activity began well after the onset of jaw closing. No significant horizontal mandibular movements were observed during ARJMs. The mandibular trajectories during opening and closing always remained close to the midline. The opening phase of ARJM cycles was associated with bilaterally synchronized activity in the digastric and lateral pterygoid muscles. The closing phase was associated with bilaterally symmetric activity in the masseter muscles. The medial pterygoid muscles displayed little or no EMG activity during ARJMs. The durations of the EMG bursts recorded in the masseter muscle were correlated with cycle time during SRJMs, as were the burst durations of the digastric and lateral pterygoid muscles during ARJMs.(ABSTRACT TRUNCATED AT 400 WORDS)     

A digital optoelectronic method for recording mandibular movement in association with oral electromyograms and temporomandibular joint noises

In order to obtain a better understanding of jaw movement and its relationship to other parameters such as muscle activity or noises from the temporomandibular joint, it is necessary to correlate these activities. A digital optoelectronic method was therefore designed to record these activities simultaneously. It uses a closed-circuit television camera to view the movement of a light source attached to the patient's lower jaw; this is then discriminated and provides an analogue or digital output (x and y axes) based on a matrix of 300 vertical division and 400 horizontal divisions covering an area of 60×80 mm in the recording plane. The recording error for static or dynamic movement is ±2·5% and movement in the z axis increases this by an additional 2·0% per cm z axis movement. Electromyograms or temporomandibular joint noises are related using adjacent channels on a recording polygraph.     

Oral physiology and mastication

Mastication is a sensory-motor activity aimed at the preparation of food for swallowing. It is a complex process involving activities of the facial, the elevator and suprahyoidal muscles, and the tongue. These activities result in patterns of rhythmic mandibular movements, food manipulation and the crushing of food between the teeth. Saliva facilitates mastication, moistens the food particles, makes a bolus, and assists swallowing. The movement of the jaw, and thus the neuromuscular control of chewing, plays an important role in the comminution of the food. Characteristics of the food, e.g. water and fat percentage and hardness, are known to influence the masticatory process. Food hardness is sensed during mastication and affects masticatory force, jaw muscle activity, and mandibular jaw movements. When we chew for instance a crispy food, the jaw decelerates and accelerates as a result of resistance and breakage of food particles. The characteristic breakage behaviour of food is essential for the sensory sensation. This study presents a short review of the influence of oral physiology characteristics and food characteristics on the masticatory process.     

内蒙古地区成年人下颌骨三维CT测量及分析

目的 为成人下颌骨缺损修复重建、重塑面部骨骼整体形态提供解剖学参数。 方法 招募志愿者49例（男21例,女28例）,收集71例下颌骨干骨标本进行CT扫描,使用Mimics软件建立内蒙古地区人120例下颌骨三维模型,测量120例内蒙古地区人下颌骨指标,并将下颌骨数据作两侧比较、男性与女性比较以及与现代华北地区下颌骨数据比较。 结果 男、女志愿者双侧所有测量数据的均无统计学差异（P>0.05）,下颌骨各项测量数据除下颌角外均为男性大于女性,下颌角女性大于男性。 结论 内蒙古地区人群较华北其他地区人群下颌骨更宽、下巴更为突出,下颌角小,咀嚼肌力量大;为内蒙古地区人群设计下颌骨假体时,设计为下颌体厚,矢状面横截面积较大,体高与下颌支高较小的形态更为合适。 【关键词】 下颌骨; 三维测量; 内蒙古地区     

Development of a novel statistical model for mandibular kinematics

The purpose of this study was to establish a new statistical method for the analysis of masticatory function. The subjects were patients with anterior crossbite who had received orthognathic surgery. Chewing movement was measured by means of an opto-electronic motion-analysis system. This movement was compared with similar movement in control patients. We sought to develop a statistical model to predict the population average curves of the chewing cycles. In this study, the mandibular incisor point was used as a target point of jaw movement. The combination of a spline function with random coefficients and self-modeling regression (SEMOR) extended to three dimensions was used to predict population average curves for each group. Unquestionably, significant differences were present in some areas. The present modeling method that uses the combination of a spline function and SEMOR is one of the best ways to eliminate subjective estimation with regard to predicting representative chewing cycles.     

Integrated actions of masticatory muscles: Simultaneous EMG from eight intramuscular electrodes

In 29 normal persons with complete dental arches, the muscular activity of the temporalis, masseter, medial pterygoid, anterior belly of the digastric, mylohyoid and geniohyoid muscles was studied electromyographically with bipolar fine wire electrodes during various mandibular movements – both resisted and unresisted. Action potentials were recorded on FM magnetic tape and each experiment was also videotaped. Temporalis muscle was active during centric closing of the jaw with either contact of the teeth, or against resistance; during free lateral movements to the ipsilateral side, either against resistance or occlusal contact; during incisor gum chewing, molar gum chewing on ipsilateral or contralateral sides, during normal mastication; and during forceful centric occlusion. Activity occurred in the masseter and medial pterygoid muscles during the following movements: closing the jaw slowly either without occlusal contact or with occlusal contact and against resistance; free lateral movement to contralateral side, either against resistance or with occlusal contact; protraction of the jaw either without occlusal contact or with occlusal contact; swallowing either saliva or water; incisor gum chewing with either the ipsilateral or contralateral molars; normal mastication; and during forceful centric occlusion. Activity occurred in the digastric, mylohyoid and geniohyoid muscles during the following movements; opening of the jaw either slowly or maximally against resistance; closing the jaw against resistance; free lateral movement to ipsilateral and contralateral sides, either against resistance or with occlusal contact; protraction against resistance of the jaw either without or with occlusal contact; swallowing saliva and water; and protraction of the tongue. They work in antagonism (reciprocally) during gum chewing and normal mastication.