口腔下颌运动教学辅助系统的开发

目的：开发下颌运动教学辅助系统，利于口腔生理教学。方法：利用计算机图形学技术，建立一个下颌骨三维数据模型，从三维六自由度下颌运动轨迹描记仪MT－1602（德国Hansen公司）获得了下颌运动轨迹原始数据，根据刚体运动规律，Microsoft Visual C 软件编程。结果：该系统能根据实测的运动轨迹真实显示下颌运动，轨迹和模型运动随意切换显示，并且此三维下颌模型能被任意旋转，从任何需要的角度来观察下颌运动。结论：该系统对下颌运动教学有较大意义。     

下颌运动分析系统在口腔修复临床应用的研究现状

随着数字化技术的发展,口腔修复领域的不同流程正在逐步跨入高效精准治疗阶段。颌位关系的正确转移是制作高质量修复体的先决条件,其中下颌运动分析系统能够记录下颌运动在动态和静态条件下的运动轨迹而显著优于传统机械面弓。当前下颌运动分析系统应用于口腔修复领域,主要包括前牙美学修复,牙体缺损修复、牙列缺损修复、颞下颌关节病变及咬合重建等。基于此,本文对下颌运动分析系统在口腔修复领域中的临床应用研究现状进行综述,以期为相关领域的临床应用和研究提供参考。     

功能性矫治器矫治安氏Ⅱ类Ⅰ分类错下颌运动轨迹初步分析

本文通过选用下切牙区下颌运动的描记，探讨用ＦＲＩ矫治器矫治安氏ⅡⅠ错，下颌运动的变化，发现型对下颌边缘运动具有引导作用，随着矫治后深覆的改善，运动轨迹随之改变；通过矫治使下颌运动轨迹重复性增加，说明下颌运动可作为一种功能监测手段，帮助分析、诊断、评价正畸疗效     

不同方法测量前伸髁道斜度和侧方髁道斜度的对比研究

目的:比较使用下颌运动描记仪、蜡牙合记录及硅橡胶咬合记录测量青年人群中个别正常牙合前伸髁道斜度、侧方髁道斜度的一致性,为临床应用提供理论依据.方法:从本学院高年级本科生中选取32例个别正常牙合,使用Zebris下颌运动描记仪(JMA)、牙合蜡以及咬合记录硅橡胶分别测量受试者的前伸髁道斜度和侧方髁道斜度.结果:下颌运动描记仪测量结果的一致性好于蜡牙合记录及硅橡胶咬合记录,其测量结果分别与蜡牙合记录及硅橡胶咬合记录比较,前伸、侧方髁道斜度均有统计学差异(P<0.05);蜡牙合记录与硅橡胶咬合记录比较,前伸、侧方髁道斜度均无统计学差异(P>0.05).结论:使用Zebris下颌运动描记仪(JMA)获取前伸、侧方髁道斜度一致性好,灵敏度高且操作便捷,有良好的临床推广价值.     

线性(牙合)总义齿与解剖(牙合)总义齿下颌运动轨迹的比较

目的了解线性总义齿和解剖总义齿修复患者的下颌运动特征及其与咀嚼功能的关系。方法利用K5AR型下颌运动轨迹描记仪,对33例线性总义齿修复患者和30例解剖总义齿修复患者的下颌运动特征包括咀嚼循环的轨迹特征、咀嚼运动幅度及运动速度等方面进行检测。结果线性总义齿的下颌运动轨迹特征不同于解剖总义齿,线性总义齿的额状面轨迹无明显接触滑动,矢状面前伸运动轨迹为直线,其咀嚼循环运动时开口最大速度相对较大,闭口最大速度相对较小(P<0.05)。结论线性总义齿具有特征性的下颌运动轨迹,反映出线性总义齿依赖良好的稳定性以充分发挥咀嚼功能。     

深覆患者升高垂直距离修复的下颌运动功能评价

目的:评价行垂直距离升高修复后下颌运动功能的变化。方法:对8例深覆患者在升高垂直距离修复前后进行切点下颌运动轨迹的描记和分析。结果:升高垂直距离后,开闭口和前伸边缘运动中垂直运动幅度有一定程度的减小;侧方接触滑动时,左右侧向运动幅度明显增加;咀嚼运动的各向运动幅度均有显著性增加。结论:深覆患者升高垂直距离能改善下颌运动功能。     

深覆He患者升高垂直距离修复的下颌运动功能评价

目的：评价行垂直距离升高修复后下颌运动功能的变化。方法：对8例深覆He患在升高垂直距离修复前后进行切点下颌运动轨迹的描记和分析。结果：升高垂直距离后，开闭口和前伸边缘运动中垂直运动幅度有一定程度的减小；侧方接触滑动时，左右侧向运动幅度明显增加；咀嚼运动的各向运动幅度均有显性增加。结论：深覆He患升高垂直距离能改善下颌运动功能。     

健康人下颌运动时头颈肩部肌电活动的研究

目的　研究健康人的下颌息止位及运动时头颈肩部肌的协同活动。方法　用肌电积分值记录分析的方法调查 1 0名健康成人的下颌息止位和各种运动时颞肌前后腹、胸锁乳突肌和斜方肌的肌电活动。结果　无论在下颌息止位还是下颌运动中 ,胸锁乳突肌和斜方肌均有相应活动 ,胸锁乳突肌活动的增加倍数与颞肌前后腹活动的增加倍数有密切的正相关关系。斜方肌在不伴咬合的各种下颌运动时活动增加 ,而在大力咬牙和咀嚼时活动趋于停止。下颌不发生偏斜时 ,同一肌的左右两侧肌的活动有密切的正相关关系。结论　颞肌前后腹、胸锁乳突肌和斜方肌均参与维持下颌息止位及下颌运动。下颌功能和头颈肩部肌功能有密切关系     

唇腭裂术后反He患者下颌运动轨迹的研究

作者对２９名单侧完全性唇腭裂术后反Ｈｅ患者及２９名普通反Ｈｅ患者进行了下颌运动轨迹的研究，发现唇腭裂术后反Ｈｅ患者的下颌运动具有如下特征：（１）下颌前伸范围大，前伸曲线平缓；（２）侧方运动范围正常，但其曲线较多地出现折转；（３）咀嚼运动水平幅度小；（４）开闭口运动轨迹交叉率高；（５）速度曲线缺口及不流畅出现率高；（６）息止Ｈｅ间隙增大，这些特征为临床上该类患者的正畸诊断和治疗方案设计，提供了依据。     

唇腭裂术后反合患者下颌运动轨迹的研究

作者对２９名单侧完全性唇腭裂术后反患者及２９名普通反患者进行了下颌运动轨迹的研究，发现唇腭裂术后反矜患者的下颌运动具有如下特征：①下颌前伸范围大，前伸曲线平缓；②侧方运动范围正常，但其曲线较多地出现折转；③咀嚼运动水平幅度小；④开闭口运动轨迹交叉率高；⑤速度曲线缺口及不流畅出现率高；⑥息止邪间隙增大。这些特征为临床上该类患者的正畸诊断和治疗方案设计，提供了依据。     

Variability of closing movements, dynamic occlusion, and occlusal contact patterns during mastication

Virtual articulation makes it possible to overcome the limitations of mechanical articulation. Novel visualization techniques have great advantages. In this study, the occlusal surfaces of the upper and lower teeth were digitized with a 3D scanner, and real functional movements of the mandible were recorded using the Jaw Motion Analyzer (JMA), an ultrasonic measurement system. A coupling component designed for clinical use in the patient's mouth was utilized for precise referencing of the movement and scan data. Similar to a two-sided impression tray, the coupling tray is used to take a joint impression of the upper and lower arches. The JMA records the positions of the mandible and the coupling component in space. The virtual articulator was designed for visualization of jaw relationships during mastication. For analysis of intercuspation, the system generates dynamic images on which closing movements/ dynamic occlusion and contact areas are highlighted. The jaw movement data are plotted to create an envelope surface representing the maximum possible space occupied by the mandible. Such an envelope surface is a type of virtual FGP (functionally generated path) bite registration. It can be applied to design virtual tooth restorations and helps to quantify the occlusal space in a virtual environment. This system can be used to individually register and utilize the variability of occlusal function.     

Influence of maximum bite force on jaw movement during gummy jelly mastication

It is known that maximum bite force has various influences on chewing function; however, there have not been studies in which the relationships between maximum bite force and masticatory jaw movement have been clarified. The aim of this study was to investigate the effect of maximum bite force on masticatory jaw movement in subjects with normal occlusion. Thirty young adults (22 men and 8 women; mean age, 22·6 years) with good occlusion were divided into two groups based on whether they had a relatively high or low maximum bite force according to the median. The maximum bite force was determined according to the Dental Prescale System using pressure‐sensitive sheets. Jaw movement during mastication of hard gummy jelly (each 5·5 g) on the preferred chewing side was recorded using a six degrees of freedom jaw movement recording system. The motion of the lower incisal point of the mandible was computed, and the mean values of 10 cycles (cycles 2–11) were calculated. A masticatory performance test was conducted using gummy jelly. Subjects with a lower maximum bite force showed increased maximum lateral amplitude, closing distance, width and closing angle; wider masticatory jaw movement; and significantly lower masticatory performance. However, no differences in the maximum vertical or maximum anteroposterior amplitudes were observed between the groups. Although other factors, such as individual morphology, may influence masticatory jaw movement, our results suggest that subjects with a lower maximum bite force show increased lateral jaw motion during mastication.     

Mandibular movement trajectories and masticatory muscle activities in the rabbit in the sleep and wake states

Jaw movements and masticatory muscle activities were recorded in freely moving rabbits. During 5 hours of continuous recording, three states were recognized, namely, sleep, rhythmical jaw movements, and wake without any major jaw movements. The rhythmical jaw movements included chewing, drinking, and grooming and were similar in characteristics to those recorded in immobilized animals. During sleep, two kinds of masseter muscle behaviors with jaw movement features were recorded: one characterized by a short EMG bursts and a pause in jaw movements, considered similar to clenching, and the other characterized by cyclic bursts and lateral jaw excursion, a grinding-like movement. The latter was correlated with light sleep, thus suggesting a resemblance between the grinding-like behavior and bruxism.     

Study on mandibular position in occlusion during opening and closing movement in hemimandibulectomy patients--effect of difference of opening distance on mandibular position]

In the hemimandibulectomy patients the mandible is severely deviated and the occlusion is unstable, therefore the prosthodontic treatment for these patients is generally not successful. To investigate the stability of the mandibular position in occlusion of these patients, the differences of the range and the position of the mandible in occlusion between during the 5-mm opening and closing movement and during the 10-mm movement were analyzed three-dimensionally with the Jaw Movement Analyzer MM-JI-E. In this study, four hemimandibulectomy patients were selected as the subjects. The findings were as follows: 1. In three subjects, the range of the mandible in occlusion during the 10-mm opening and closing movement was larger than that during the 5-mm movement in almost all directions. On the contrary in one subject, the range of the mandible in occlusion during the 10-mm opening and closing movement was smaller than that during the 5-mm movement in almost all directions. 2. The relative relationship of the mandibular position in occlusion during the 10-mm opening and closing movement to that during the 5-mm movement varied in four subjects. In one subject, the mandible rotated horizontally towards the outside and moved upward. In another subject, the mandible rotated horizontally towards the inside and moved downward. In the other subject, the mandible moved inward and upward. In the other subject, the mandible moved outward and downward.     

Relationship between condylar and incisor point displacement during habitual maximum open-close movements

SUMMARY The relationship between condylar movements and incisor point movements during habitual maximum open-close movements were studied in 10 healthy male and 10 healthy female subjects. Jaw movements were recorded by means of an opto-electronic jaw movement recording system, OKAS-3D, capable of recording the six degrees of freedom at a sample frequency of 300 Hz. The lower jaw position of the lateral pole of the condyles was found by means of palpation. In order to analyse the movements, the opening and closing path of the incisor point were divided into ten equal intervals and the corresponding condylar displacement in each interval was calculated. A displacement index was obtained by normalizing the condylar displacement with respect to the maximum condylar displacement. Due to the normalization, the displacement index is not sensitive to possible errors in the location of the lateral condylar point. A clear condylar displacement was already recorded in the first movement interval, right at the start of opening (average displacement index in the first opening interval was significantly greater than zero, P < 0.0005). The condylar displacements in the start and the end interval of opening and closing were smaller than in the intermediate movement intervals ( P < 0.00005).     

Simple system to record jaw movements by a home digital camcorder

PURPOSE: Systems of recording jaw movements that are used in prosthodontics and orthodontics are too expensive and complicated for daily clinical diagnosis. This pilot study presents the development of a simple system using a camcorder and motion-capturing software. MATERIALS AND METHODs: Markers to detect jaw movement were attached to the mandibular incisors of a subject. A mirror was assembled beside the subject's face to detect anteroposterior movement. Jaw movements were recorded by a home digital camcorder. Movements of the markers were analyzed by motion-capturing software and transferred to 3-D data. The results were compared with those of a conventional system. To examine the accuracy of the measurements, the markers were placed on a computer-controlled x-y working stage and displaced. The positions of the markers were measured and analyzed, then compared with the true values indicated by the x-y working stage. RESULTS: The trajectories of the mandibular incisors recorded by the new system were very similar to those of the conventional system. On measurement accuracy, the mean differences between the measured and true values of the vertical and transverse movements were 0.07 mm (SD 0.03) and 0.06 mm (SD 0.04), respectively. On anteroposterior movement, the difference was 0.11 mm (SD 0.05). CONCLUSION: This new system can be useful for simple recording of jaw movements with satisfactory accuracy.     

Isotonic resistance jaw exercise alters jaw muscle coordination during jaw movements

The aim was to investigate the effects of isotonic resistance exercise on the electro‐myographic (EMG) activity of the jaw muscles during standardised jaw movements. In 12 asymptomatic adults surface EMG activity was recorded from the anterior temporalis and masseter muscles bilaterally and the right anterior digastric muscle during right lateral jaw movements that tracked a target. Participants were randomly assigned to a Control group or an Exercise group. Jaw movement and EMG activity were collected (i) at baseline, before the exercise task (pre‐exercise); (ii) immediately after the exercise task (isotonic resistance at 60% MVC against right lateral jaw movements); (iii) after 4 weeks of a home‐based exercise programme; and, (iv) at 8‐weeks follow‐up. There were no significant within‐subject or between‐group differences in the velocity and amplitude of the right lateral jaw movements either within or between data collection sessions (P > 0·05). However, over the 8 weeks of the study, three of the tested EMG variables (EMG Duration, Time to Peak EMG from EMG Onset, and Time to Peak EMG activity relative to Movement Onset) showed significant (P < 0·05) differences in the five tested muscles. Many of the significant changes occurred in the Control group, while the Exercise group tended to maintain the majority of the tested variables at pre‐exercise baseline values. The data suggest a level of variability between recording sessions in the recruitment patterns of some of the muscles of mastication for the production of the same right lateral jaw movement and that isotonic resistance exercise may reduce this variability.     

Human jaw muscle motor behaviour. I. Motor drive

Jaw muscle motor behaviour, however complicated, has important implications for the every day dental practice. In recent years the understanding of jaw and other skeletal muscle function has increased considerably. Direct recording of primary afferent discharge in conscious human beings and animals during normal function has caused radical changes of the concepts of muscle receptor function. Central pattern generators at segmental levels and suprasegmental programming centres are important mechanisms behind voluntary and automatic movements of different kinds. The most important proprioceptive function is probably to provide reassurance of correct movement pattern, to adjust the central programming to environmental changes and to directly influence slow movements requiring precision. Muscle spindle receptors contribute to mandibular kinesthesia. Muscle spindles are rarely present in jaw opening muscles. Despite this fact an excitatory reflex similar to the stretch reflex but with longer latency has been demonstrated. Further on a reciprocal organisation with antagonist inhibition has been shown to exist between jaw openers and closers. Motor behaviour of jaw and limb muscles thus seem to have many characteristics in common.     

Trajectories of condylar points during working-side excursive movements of the mandible

STATEMENT OF PROBLEM: Trajectories of different condylar points provide different interpretations of condylar movement during open-close jaw movements. Movement of the working-side condyle is often assessed clinically by recording the trajectory of a single arbitrary condylar point. PURPOSE: This study examined the effect of the differences in condylar point location on condylar point movement trajectories during a working-side movement. METHODS: Different points exhibited different trajectories during a single working-side movement in each of 44 subjects. RESULTS: Up to 40% of a point's displacement could be attributed simply to the location of the point. CONCLUSIONS: Interpretation of condylar movement on the working side within a subject depends on the point chosen.