髁突运动中心大张口轨迹与关节窝形态的关系及临床应用探讨

目的　探讨髁突运动中心大张口轨迹与关节窝形态的关系 ,对TMD患者髁突运动中心轨迹特征进行初步研究。方法　利用自行开发的髁突运动中心轨迹显示分析系统 ,分别以运动中心、终末绞链轴点作为参考点 ,观察 10名健康人和 7例临床检查怀疑盘前移位的TMD患者大张口轨迹 ,与磁共振成像得到的相应关节窝形态及关节盘位置诊断结果进行比较。结果　健康人左右侧运动中心轨迹与关节窝形态曲线重合率分别为 80 % (8/ 10 )和 90 % (9/ 10 ) ;终末绞链轴点轨迹与关节窝形态重合率均为 0 (0 / 10 )。TMD患者中 ,11侧盘前移位关节 ,除 1侧可复性盘前移位关节外 ,髁突运动中心轨迹均与正常的轨迹明显不同 ,出现各种改变 ;3侧正常盘位关节 ,髁突运动中心轨迹均与健康人的轨迹相似。结论　运动中心轨迹较终末绞链轴点个体稳定 ,可认为是较理想的研究髁突运动轨迹的参考点     

颜面不对称患者开闭口时的髁突运动轨迹特征

目的通过记录颜面不对称患者的髁突运动轨迹,研究颜面不对称患者的髁突运动规律.方法颜面不对称患者24人,其中男性9人,女性15人.使用CADIAXⅢ型(Computer Aided Diagnosis Axiograph)髁突运动记录仪,记录患者在不同下颌运动时的髁突运动轨迹,对开闭口运动时的髁突运动轨迹特征进行分析.结果颜面不对称患者双侧髁突开闭口轨迹具有不对称性,偏斜侧(下颌颏部所偏向的一侧)的轨迹弧度大于非偏斜侧,定量分析大张口时双侧髁突的运动距离、矢状面、水平面的倾斜度没有显著性差异,在髁突运动5mm时双侧髁突在矢状面、水平面的倾斜度偏斜侧大于非偏斜侧,具有显著性差异.髁突铰链轴的旋转度比正常(牙合)人群要高.结论颜面不对称患者不仅具有形态结构的不对称,髁突运动轨迹在长度、角度等方面也呈现一定的不对称性.     

下颌绞链运动轴点稳定性及位置的探讨

本研究的目的在于探讨下颌绞链运动轴点的位置是否恒定以及它是否位于髁突中心点。采用新型的三维下颌运动轨迹描记仪ＭＴ－１６０２测量了１４名健康人在４次重复性实验中，下颌小张闭口运动绞链轴点的稳定性及其与髁突的位置关系。结果表明，下颌后退位的小张闭口运动所测得的绞链轴点位置不恒定，存在瞬间绞链轴点。双侧绞链轴点基本均匀地分布于髁突四周，其距髁突中心点的平均距离为８．８３±５．６５ｍｍ。这一结果对临床正确使用架有直接的参考价值。     

单侧后牙锁患者前伸及后退髁突运动轨迹的研究

目的探讨单侧后牙锁者在下颌前伸、后退运动过程中髁突运动轨迹的特征及其与正常者之间的差异。方法选择单侧后牙锁患者24例和个别正常25例,应用髁突运动轴图描记仪(computer aided diagnosis axiograph,CADIAX)记录下颌前伸、后退运动时髁突的运动轨迹。结果实验组在下颌前伸、后退运动过程中髁突轨迹曲折、不流畅、重合性差,两侧髁突运动不对称、侧方位移增大;其锁侧在矢状方向和空间位移上以及髁突矢状面倾斜度小于非锁侧(P<0.05),锁侧髁突矢状面倾斜度较对照组小(P<0.05),在髁突位移5mm处水平面髁突倾斜度大于对照组(P<0.05)。结论单侧后牙锁者下颌前伸、后退运动时两侧髁突运动不对称,侧方位移增加。     

正常开闭口时髁突运动的轨迹特征

目的　通过对正常人群下颌运动中髁突运动的测量记录 ,从而确定正常在开闭口运动中髁突的运动特征。方法　正常 38人 ,其中男女各 19人 ,平均年龄 18.7岁。应用CADIAXⅢ型 (Com puterAidedDiagnosisAxiogragh)髁突运动仪 ,记录下颌在各种边缘运动时的髁突运动情况 ,对开闭口时的髁突运动情况加以分析。结果　定性研究结果表明正常髁突运动轨迹对称 ,光滑 ,重复性好。男女性别无显著差异。在大张口时髁突相对于参考位置 (ReferencePosition)的最大位移左侧为 16 .0 2± 4 .2 7mm ,右侧为 16 .33± 5 .6 4mm ,髁突在位移 5mm时的矢状面倾斜度分别为右侧 35 .2 3± 8.18°,左侧 33.10± 8.6 6° ;在水平面内的髁突倾斜度右侧为 - 2 .0 0± 2 .6 7° ,左侧为 0 .39± 2 .18° ,大张口时绞链轴的旋转度 (GAMMA值 )为 2 6 .18± 6 .2 2°。结论　正常髁突运动轨迹有其典型的轨迹特征 ,但也存在较大的个体差异     

正常He开闭口时髁突运动的轨迹特征

目的 通过对正常He人群下颌运动中髁突运动的测量记录,从而确定正常He在开闭口运动中髁突的运动特征。方法 正常He38人,其中男女各19人,平均年龄18．7岁。应用CADIAXⅢ型（Computer Aided Diagnosis Axiogragh)髁突运动仪,记录下颌在各种边缘运动时的髁 突运动情况,对开闭口时的髁突运动情况加以分析。结果 定性研究结果表明正常He髁突运动轨迹对称,光滑,重复性好。男女性别无显著差异。在大张口时髁突相对于参考位置（Reference Position)的最大位移左侧为16．02&#177;4．27mm,右侧为16．35&#177;5．64mm,髁突在位移5mm时的矢状面倾斜度分别为右侧35．23&#177;8．18&#176;,左侧33．10&#177;8．66&#176;;在水平面内的髁突倾斜度右侧为－2．00&#177;2．67&#176;,左侧为0．39&#177;2．18&#176;,大张口时绞链轴的旋转度（GAMMA值）为26．18&#177;6．22&#176;。结论 正常He髁突运动轨迹有典型的轨迹特征,但也存在较大的个体差异。     

下颌前突患者下颌支矢状劈开截骨术后髁突运动轨迹的改变

目的:研究双侧下颌支矢状劈开截骨术对下颌前突患者髁突运动轨迹的影响。方法:采用ARCUSdigma下颌三维运动轨迹描记仪,以髁突运动中心为参考点,研究30例正常受试者、14例下颌前突患者手术前后开口、前伸和左右侧向髁突运动的轨迹。用SPSSV11.0统计软件包进行配对t检验和成组t检验。结果:下颌前突患者术前、术后、正常组左侧髁突的运动轨迹与右侧基本相同,左侧髁突与右侧的开口、前伸和侧方运动范围无显著性差异(P>0.05)。术前组与正常组髁突运动轨迹差别较大,术前开口、前伸和侧方运动范围均小于正常组(P<0.05);术后与正常组髁突运动轨迹接近,术后开口、前伸和侧方运动范围与正常组无统计学差异;术前与术后组髁突运动轨迹差别较大,术前开口、前伸和侧方运动范围均显著小于术后组(P<0.05)。结论:下颌前突患者手术后,随着术后正畸治疗及咬合自我调整,建立了正常的咬合引导关系,使下颌功能运动趋向正常。     

下颌偏斜患者下颌侧方运动时髁突的运动轨迹特征

目的 通过记录下颌偏斜患者的髁突运动轨迹，研究此类患者髁突运动的规律。方法 下颌偏斜患者31例（男性9例，女性22例），年龄12～26岁，平均18岁。使用CADIAX　Ⅲ型髁突运动轨迹轴图描计仪，记录并通过配对t检验和秩和检验分析患者下颌侧方运动时髁突的运动轨迹，并将其与患者下颌偏斜量进行多元线性回归分析。结果下颌偏斜患者下颌侧方运动时髁突的运动轨迹不对称，偏斜侧的运动位移大于非偏斜侧，差异有统计学意义（P＜0．01）；偏斜侧髁突的水平倾斜度小于非偏斜侧，差异有统计意义（P＜0．01）。随着偏斜量的增加，偏斜侧与非偏斜侧髁突的位移差距也相应增加，非偏斜侧髁突的位移相应减小，差异有统计学意义（P＜0．05）。结论下颌偏斜患者不仅颅面形态不对称，下颌侧方运动时髁突运动轨迹在长度、角度等方面也不对称，其与偏斜量有一定的相关性。     

安氏Ⅱ类1分类深覆患者髁突运动轨迹特征的研究

目的通过对正常人和安氏Ⅱ类1分类深覆患者下颌前伸后退和开闭运动中髁突运动的记录对比,从而确定安氏Ⅱ类1分类深覆患者的髁突运动特征。方法正常人和安氏Ⅱ类1分类深覆伴发深覆盖患者各30例,应用计算机辅助髁突运动轴图轨迹描记仪（CAD IAXⅢ）记录在下颌功能运动时髁突的运动情况,对两组的髁突运动情况进行比较和分析。结果定性研究结果表明安氏Ⅱ类1分类深覆患者在两种运动中髁突运动轨迹都较正常人平缓,前后向的距离明显大于垂直向,开闭口运动中垂直向上最大位移在运动的中期。定量分析发现,安氏Ⅱ类1分类深覆患者在矢状向、垂直向、空间位移均较正常人小。结论安氏Ⅱ类1分类深覆患者较正常人在三维方向上有较典型的髁突运动轨迹。     

安氏Ⅱ~2错(牙合)髁突运动轨迹特征的研究

目的探讨安氏Ⅱ^2错（牙合）的髁突运动轨迹特征并分析关节弹响与髁突运动的相互影响。方法选取安氏Ⅱ^2错（牙合）19例,伴关节弹响的安氏Ⅱ^2错（牙合）18例,个别正常矜20例;应用髁突运动轴图描计仪（computer aided diagnosis axiograph,CADIAX）Ⅲ型记录各种下颌运动时其髁突运动轨迹。结果安氏Ⅱ^2错（牙合）开闭口轨迹矢状位移减小,垂直位移增大;前伸后退轨迹垂直向位移增大。伴关节弹响者开闭口轨迹垂直向位移和髁突最大空间位移均增大;侧方运动轨迹非工作侧髁突空间位移增大。髁突位移5mm时的矢状面倾斜度在各种下颌运动时均大于个别正常骆（P〈0．05）。结论安氏Ⅱ^2错（牙合）的髁突运动轨迹特征与前牙内倾性深覆矜有关,关节弹响可影响髁突运动的协调性。     

Anatomical location of various condylar points for jaw movement analysis in Japanese women

Summary The aim of this study was to determine anatomical locations of the hinge axis point, kinematic axis point and reference point for the palpated lateral condylar pole on lateral cephalograms. Subjects comprised 18 Japanese women selected according to following criteria: normal occlusion; and absence of signs and symptoms of stomatognathic function. Jaw movement and the condylar reference points noted earlier were recorded three‐dimensionally with six degrees of freedom, and kinematic axis point and hinge axis point were determined using an optoelectronic jaw‐tracking system. Lateral cephalograms were used to determine anatomical locations of the three points in the condyle. Mean location of hinge axis point was 12·9 mm anterior of the porion and 5·3 mm inferior to the Frankfort horizontal plane, the kinematic axis point was situated in 12·8 mm anterior and 0·1 mm inferior, and the reference point for the palpated lateral condylar pole was situated 10·7 mm anterior and 0·8 mm inferior, respectively. The kinematic axis point was located outside the condyle in the majority of subjects. The reference point for the palpated lateral pole offers a useful indicator in the analysis of condylar movements.     

Accuracy of a predetermined transverse horizontal mandibular axis point

STATEMENT OF PROBLEM: The transverse horizontal mandibular axis point may be located most precisely by a kinematic process. However, an anatomical method of locating the axis is also an acceptable technique, and an easily determined point that is consistently close to the kinematic axis would simplify transfer of the arc of rotation from the patient to the articulator. PURPOSE: This in vivo study compared the location of an anatomically predetermined hinge axis point with the determined kinematic axis. MATERIAL AND METHODS: Forty subjects (27 males, 13 females; 23 to 47 years of age) with functionally acceptable occlusion and no detectable clinical signs of temporomandibular disorders participated in the study. The earpiece alignment flags on a mechanical SAM Axiograph III combination flag/face-bow were used to locate the right and left predetermined hinge axis points, 10 mm anterior to the earpiece. The right and left kinematic center of rotation was located as described by Lauritzen and confirmed with the PC Axiotron electronic Axiograph to within 0.25 mm. All points were transferred to 1 mm(2) grid paper on the subject's skin. The distance between each predetermined and kinematic point was measured +/-0.25 mm. Wilcoxon and Mann-Whitney tests were used to examine differences between the left and right axis points and potential significant differences between genders at a significance level of P<.05. The number of occurrences and the distance of the predetermined axis points from the kinematic axis also were described. RESULTS: The mean distance between points was 1.1 mm on the right (range 0.0 to 3.0 mm), 1.2 mm on the left (range 0.0 to 3.0 mm), and 1.1 mm for all 80 points (+/-0.63). More than 96% of the predetermined points were within 2 mm of the kinematic axis, and 67% were within 1 mm. There was no significant difference between the right and left points and no significant differences based on gender. CONCLUSION: Within the limitations of this study, the results suggest that the predetermined axis point is well within the clinical norm for estimated location of the transverse horizontal mandibular axis.     

The intra-articular distance within the TMJ during free and loaded closing movements

Previous studies on free opening and closing movements of the mandible have demonstrated that the opening movement traces of the condylar kinematic center (i.e., the condylar point for which the protrusive and the opening movement traces coincide) lie closer to the articular eminence than the closing traces. This indicates the presence of an intra-articular distance within the joint during free closing. Since the mandible behaves like a class III biomechanical lever, a counteracting mechanical load on the mandible during closing will press the condyle-disc complex against the articular eminence. Therefore, in this study the hypothesis was tested that the difference between opening and closing movement traces of the kinematic center is reduced when the closing movements are counteracted by a mechanical load. From 10 healthy participants, 20-second movement recordings were obtained by a six-degrees-of-freedom opto-electronic jaw movement recording system (OKAS-3D) for three types of movements: (1) free opening and closing movements, (2) free opening and loaded closing movements (i.e., the participants closed against a small or high manually applied downward-directed force to the chin), and (3) gum chewing. Off-line, the opening and closing movement traces of the kinematic center were reconstructed, and the average difference between the traces (the intra-articular distance) was calculated. The average intraarticular distance was significantly smaller during loaded closing than during free closing, whereas no significant differences were found in the intra-articular distances between the loaded situations of low and high manual loading and contralateral chewing (ANOVA and post hoc Bonferroni multiple comparisons of means test, p<0.005). In conclusion, loading of the mandible during closing movements reduces the intra-articular distance within the temporomandibular joint.     

Location of the hinge axis and the kinematic centre in asymptomatic and clicking temporomandibular joints

The study aimed to compare the locations of the hinge axis and the kinematic centre in both clicking and non-clicking TMJs. The six degrees of freedom optoelectronic jaw movement recording system OKAS-3D was used to record open/close movements in 10 asymptomatic subjects and 30 subjects with a clicking joint. Movement paths of the hinge axis and the kinematic axis were calculated. A t-test was used in the analysis of the locations of the two condylar movement reference points. Variances between the values of the hinge and the kinematic axes were compared with the F-test. Locations of the hinge axis and the kinematic centre on the average did not differ significantly for the asymptomatic subjects at the group level (P>0. 05), while individually the locations differed 4.96 mm on the average. The difference between the hinge axis and the kinematic axis was significant for the group of subjects with clicking joints (P<0.01), with the average individual level difference of 9 mm. Variances differed significantly between the coordinates of the hinge and the kinematic axes between the two groups of subjects (P<0. 01). The study shows the importance of the choice of a condylar movement reference point for the study of condylar movements and suggests the use of the kinematic centre in such studies.     

Size of variables in mandibular movements in autopsy material

Autopsy was performed on the right temporomandibular joint in eleven individuals with a mean age of 71 years. Standard positions indicative for protrusion, laterotrusive border movement and posterior opening movement were photographed in the sagittal plane. Size of movements of the disc and condylar head were recorded, as well as movements of a reference point in the mental region. The slope of the anterior discal movement was estimated and mandibular rotation during posterior opening was registered. Centre of rotation during the hinge movement was in all cases located to the craniodorsal part of the condylar head. Attempt to construct centres of rotation in the eminence and condylar head for the horizontal movements was in vain. The discussion deals with the influence of the specific kind of material on the results and the possible systematic differences to clinical material.     

Relationship between kinematic center and TMJ anatomy and function

The kinematic center (KC)-defined by coinciding jaw-opening/-closing and protrusion-retrusion trajectories-has been proposed in the literature as a reference point to represent TMJ movements. In this study, we tested whether the KC lies in a peculiar anatomical point and whether its trajectory reflects intra-articular distance. In 11 asymptomatic individuals (seven females, four males, aged 24-37 yrs), 4 openings/closings and 4 protrusions/retrusions were tracked with dynamic stereometry. In a 3D lattice (0.5 mm grid) constructed solidly around each condyle, the KC was the point with maximal cross-correlation between opening-closing and protrusion-retrusion paths. KC trajectories were more cranial on closing than on opening, consistent with intra-articular distances being smaller on closing than on opening. However, KCs were never located on condylar main axes (distance, 4.5 +/- 2.9 mm), nor did they coincide with points best approximating fossa shapes (distance, 12.5 +/- 6.4 mm). The kinematic center's anatomical and functional significance therefore appears to be questionable.     

Study on the reconstruction of a four-dimensional movement model and the envelope surface of the condyle in normal adults

The objective of this study was to reconstruct the envelope surface of the condyle and the four-dimensional trajectory model in mandibular border movement in normal adults. Eleven healthy subjects were selected as volunteers. Cone-beam computed tomographic (CBCT) scanning was performed on the volunteers. The three-dimensional (3D) movement path of the mandible was recorded using a virtual articulator (PN-300), which was based on a 3D model of the mandible. We used Proplan CMF 3.0 (Materialise) software to perform this from the DICOM data generated by CBCT scans. The distance of condylar movement was measured in this model during volunteers’ mouth opening, protrusion, and lateral excursions. The envelope surface of the condyle was reconstructed by merging a functional condylar surface at each recording moment during the movement of the whole border. In the mandibular digital models, the condyle moved downward firstly, and moved upward to the position of maximum mouth opening. The condyle moved forward and downward during protrusion. The working condyle rotated slightly and the non-working condyle moved forward, downward, and inward during lateral excursions. The mean (SD) movement distance of 11 subjects was 19.04 (4.37) mm during mouth opening (including downward and upward) and 9.75 (2.38) mm during protrusion. During lateral excursions the mean (SD) movement distance of the working condyle was 2.87 (1.13) mm, the mean (SD) movement distance of the non-working condyle was 10.85 (3.25) mm. The envelope surface of healthy volunteers showed a double-peak pattern. The envelope surface of the condyle and four-dimensional movement model can be reconstructed by merging the trajectory of the mandible recorded from the novel virtual articulator PN300 and a 3D image of the mandible.