A comparison and validation of amorphous sensor condylar movement analysis to MRI diagnosis of anterior disc displacement

This study compared temporomandibular joint condylar movements in a sample of six patients with clinically normal joints, with those of nine patients with joints diagnosed by magnetic resonance imaging (MRI) to have anterior disc displacement with reduction (ADD). The aim of this study was to compare and validate the use of the amorphous sensor to MRI diagnosis in condylar movement analysis. The measuring device consisted of an amorphous sensor and a small magnet. Condylar and jaw movements were recorded simultaneously over the course of 10 open-close cycles. Maximum velocity of condylar movement during the opening phase in the ADD joints was significantly higher than the normal joints. The degree of jaw opening at the turning point of condylar movement in the ADD joints was significantly larger than the normal joints. The diagnostic sensitivity and specificity of the maximum velocity of condylar movement during the opening phase was 75.0 and 75.0%, respectively, while those of the degree of jaw opening at the turning point of condylar movement were 91.7 and 91.7%, respectively. These results suggest that the analysis of condylar movement, employing the amorphous sensor may be a reliable method for diagnosis of ADD.     

Local kinematic and anthropometric factors related to the maximum mouth opening in healthy individuals

The aim of the present study was to investigate the influence of local anthropometric (mandibular length and width) and kinematic (forward and downward condylar translation and angle of rotation) variables upon the maximum mouth opening (MMO). Thirty-five healthy individuals, 17 men and 18 women, mean age 23 years with a range from 18 to 31 years, performed six to eight maximal, symmetrical and pain-free open-close movements during a 20-s recording. Mandibular movements were recorded by means of the OKAS-3D jaw movement recording system. A stepwise regression analysis showed that differences in MMO are mainly explained by differences in the angle of rotation and in mandibular length (R2adj=91.5%). Including the downward and forward component of condylar translation into the regression model increased the explained variance with only 4.7%. A second stepwise analysis showed that the angle of rotation is positively related to the forward component of the condylar translation and negatively related to its downward component (R2adj=52.7%). In conclusion, differences in MMO between healthy individuals are, to a large extent, explained by differences in the angle of rotation and in mandibular length. In its turn, differences in the angle of rotation are related to differences in condylar translation.     

Correlation between facial morphology,mouth opening ability,and condylar movement during opening-closing jaw movements in female adults with normal occlusion

The aim of this study was to investigate the relationship between parameters of facial morphology, maximal voluntary mouth opening ability, and condylar movements in 21 adult females, aged between 20 and 24 years. The subjects had a normal occlusion without sign or symptoms of temporomandibular joint (TMJ) dysfunction. Mandibular movements were recorded using an opto-electric jaw movement recording system with six degrees of freedom under a series of maximal mouth opening-closing movements. Maximal jaw opening and coincident condylar movement were measured three-dimensionally. The mean values of the incisor and condylar path were 41.1 +/- 3.5 mm (range 35.6-50.9 mm) and 12.8 +/- 2.8 mm (range 8.1-19.2 mm), respectively. Although the positive correlation between maximal jaw opening and facial morphology was significant, none of the variables significantly differed between the value of the condylar path and facial morphology. The length of the path of maximum incisor movement and the condylar path during mandibular movement also did not correlate. Stepwise multiple regression analysis indicated a positive association between the maximal length of the incisor path and the cephalometric value of mandibular ramus inclination (R2 value was 0.369). The results of this study suggest that facial morphology size has a limited effect on maximal voluntary mandibular opening and condylar movements in normal adult female subjects.     

Expression of matrix metalloproteinase-2 and -9 in synovial fluid of the temporomandibular joint accompanied by anterior disc displacement

The purpose of this study was to determine whether or not matrix metalloproteinases (MMPs) in synovial fluid are helpful in the biochemical diagnosis of temporomandibular joint (TMJ) disorder (TMD). We examined the synovial fluid from 38 TMD patients with disc displacement and 20 volunteers by gelatin zymography and immunoblotting analysis to clarify the involvement of the joint pathology from the viewpoint of expression of MMPs. Two gelatinolytic enzymes, MMP-2 and -9, were detected in the samples. The incidences of expression, except for pro-MMP-2, in anterior disc displacement (ADD) without reduction (ADD w/o R) were significantly higher than in ADD with reduction (ADD w R) (P<0.05). Quantitative analysis showed that the degree of MMP-2 and -9 expression in ADD w/ o R were higher than in ADD w R. These data suggest that the presence or absence of disc reduction is a major turning point in the process of joint destruction, and these MMPs are useful as biochemical markers for TMD diagnosis.     

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     

Associations between incisor and mandibular condylar movements during maximum mouth opening in humans

This study evaluated the common clinical assumption that condylar translation and mouth opening at the incisor are closely related. The sample studied comprised 27 adult females (23-35 years), selected for normal temporomandibular function, occlusion, and skeletal patterns. Condylar and mandibular central incisor movements (straight-line distances and curvilinear pathways) were recorded in three dimensions (3D) for 20 s with an optoelectric (Optotrak(R)) jaw-tracking system while each participant performed multiple maximum opening cycles. Masticatory analysis and multilevel statistical programs computed the 3D movements of the incisors and condylar hinge axis during opening and closing. The incisor point moved an average straight-line distance of 46.6 mm during opening and 45.9 mm during closing; the lengths of the opening and closing curvilinear pathways were 48.6 and 47.7 mm, respectively. The condyles moved average straight-line distances of 11.9 and 12.2 mm during opening and closing, respectively. The condyles' curvilinear pathways during opening and closing were 14 and 14.6 mm, respectively. Ranges of condylar movement varied widely between individuals. The straight-line distances and curvilinear pathways were highly correlated for the incisors (R=0.98) and the condyles (R=0.98). Neither the straight-line distances nor curvilinear pathways of the incisors were correlated with those of the condyles. Incisor straight-line distances and curvilinear pathways were moderately correlated with mandibular rotation (R(between subjects)=0.82 and R(between repeats)=0.88). During repeated openings, both condylar and incisor excursions increased, but during repeated closings only incisor excursions increased. It is concluded that (1) maximum incisor opening does not provide reliable information about condylar translation and its use as a diagnostic indicator of condylar movement should be limited, (2) healthy individuals may perform normal opening with highly variable amounts of condylar translation, (3) the straight-line distances of the incisor and condyles provide adequate information about the length of the curvilinear pathway, and (4) variation in maximum incisor opening is largely explained by variation in the amount of mandibular rotation.     

Ipsilateral interferences and working-side condylar movements

There is limited knowledge of the effects of the occlusion on temporomandibular joint function. AIM: The aim was to investigate the influence of a working-side occlusal alteration (OA, i.e. interference) on trajectories of working-side condylar points during standardized lateral jaw movements (laterotrusion) tracked by a jaw-tracking system. METHODS: Ten trials of right laterotrusion were repeated under: control 1 (before OA), OA (immediately after placement of a working-side interference) and control 2 (immediately after removal of OA) conditions. RESULTS: During right jaw movement, the paths of the working-side condylar points under OA were significantly more inferior and anterior to those under control at the same amount of mid-incisor-point displacement from the intercuspal position. The OA significantly reduced the rotation of the mandible about the antero-posterior and supero-inferior axes and significantly increased the opening angle. Controls 1 and 2 were not significantly different. CONCLUSIONS: A working-side interference has an immediate, significant effect on working-side condylar movement.     

Reduced joint distance during TMJ movement in the posterior condylar position

Biomechanical loading reduces joint distance and has a causative relationship with disc displacement in temporomandibular joint and/or osteoarthritis. Condylar movement and pathways during mouth opening and closing are different depending on the condylar position in the glenoid fossa. Therefore, physical loading on the articular disc or condylar head would also be different in different condylar positions. The aim of this study was to evaluate the 3-dimensional changes of joint distance in different anterior–posterior condylar positions. We divided 52 temporomandibular joints into anterior, concentric, and posterior condylar positions using transcranial radiographs. We traced the condylar movements by simulating mandibular movement with 3-dimensional computed tomography data and a position-tracking camera. The joint distance during temporomandibular joint movement was significantly narrower, and the length of condylar pathways with narrower joint distance was longer in the posterior condylar position than in the concentric (p < 0.05) or anterior condylar positions (p < 0.01). Our study suggests that the posterior condylar position experiences more physical loading than other positions. Therefore, the position may have an accelerating or worsening effect on biomechanical loading-related temporomandibular joint disorder in cases of harmful parafunctional activities such as excessive mouth opening, clenching, and bruxism.     

Functions of condylar translation in human mandibular movement

Mandibular movement in many mammals is controlled by a pure hinge joint. Since condylar translation is a structurally complex adaptation and a common source of human clinical dysfunction, there have been many attempts to evaluate the biologic significance of human condylar translation. The three hypotheses concerning condylar translation considered in this study are (1) that it results in a center of rotation of the mandible in the area of the mandibular foramen, minimizing displacement of the inferior alveolar neurovascular bundle during mandibular movement, (2) that it reduces the amount of stretch in the masseter muscle during opening, allowing the muscle to function within an efficient portion of the muscle fiber length-tension curve, and (3) that it prevents compromise of the airway and other cervical structures by the tongue and mandible during opening. Ten subjects with cephalometric radiographs taken both in centric relation and with the mandible wide open are evaluated. The movement of the mandibular foramen, the stretch of the masseter muscle, and the proximity of the tongue and mandible to the airway are compared during actual opening and when mandibular opening is modeled as a pure hinge movement. The results indicate that condylar translation performs all three functions. However, a review of other data leads to the conclusion that airway preservation in human beings may be a more critical problem and a more essential function of condylar translation than either reducing movement of the mandibular foramen or reducing stretch of the masseter muscle.     

Electromyographic activity of the human lateral pterygoid muscle during contralateral and protrusive jaw movements

Understanding of the normal function of the lateral pterygoid muscle is limited. The principal aim here was to determine whether there is a progressive increase in lateral pterygoid activity as the mandibular condyle moves downwards and forwards as would be expected if the muscle is concerned with the precise horizontal positioning of the mandible. In eight humans, recordings were made of the activity of the superior (SHLP) and inferior (IHLP) heads of the lateral pterygoid and the masseter, anterior temporal, posterior temporal and digastric muscles, together with the movement of the palpated lateral condylar pole (JAWS-3D tracking system) during trials of a contralateral and a protrusive jaw movement. Recording sites in SHLP and, in one participant, IHLP were verified by computed tomography. In each participant there was a progressive increase in the rectified and smoothed SHLP and IHLP activity in association with condylar movement during the contralateral and protrusive jaw movement. Further, irregularities in condylar movement, which reflected variations in the rate at which the jaw was moved, were correlated in time with prominent bursts of SHLP and IHLP activity. In all participants there was a consistently high correlation coefficient between the rectified and smoothed SHLP and IHLP activity and condylar displacement during the contralateral or protrusive jaw movements. For example, the mean (+/-SD) correlation between anterior condylar translation during contralateral excursion and SHLP activity was 0.91+/-0.09, and for IHLP 0.96+/-0.02. For the masseter, anterior temporal, posterior temporal and digastric muscles, mean r-values were, respectively, 0.10+/-0.77; -0.14+/-0.72; 0.24+/-0.78; 0.54+/-0.47. When treated as a group the correlation coefficients for SHLP and IHLP were statistically significantly different from the correlation coefficients for the other muscles treated as a group (ANOVA; p < 0.002 for correlation with anterior translation). These observations support the notion that the lateral pterygoid provides the principal driving force for moving the jaw forwards or laterally in protrusive or lateral excursive condylar movements. Further, the data suggest that the muscle plays a part in the fine control of jaw movements.     

面部不对称畸形颞下颌关节盘的磁共振研究

目的旨在探讨面部不对称患者两侧颞下颌关节盘的形态和功能是否存在差异及面部不对称与关节盘内部结构紊乱之间可能存在的相关关系。方法对37名面部不对称者(10男,27女)的74个关节应用高清晰度的磁共振技术在矢状位(开口和闭口)和冠状位(闭口)进行扫描。将关节盘移位的类型分为部分前移位、前移位、旋转及侧向移位五种类型。将关节盘的功能分为正常、可复性移位和不可复性移位三组。在矢状向闭口位影像上将关节盘的形状分为双面凹、双面平、烟囱状和严重变形五种。同时对关节盘的位置、开口运动中的移位和旋转进行定量测量。对偏斜侧和非偏斜侧的差异进行统计学分析。结果本样本中约70%的面部不对称患者存在一侧或两侧的关节内部结构紊乱;关节盘前移位,特别是旋转性前移位在偏斜侧较多见(P<0.01);偏斜侧和非偏斜侧的关节盘形态有显著的统计学差异(p<0.01),偏斜侧形态异常者较多;偏斜侧关节盘的位置明显靠前、靠下(p<0,01);非偏斜侧关节盘在开口过程中表现出较大的运动幅度。结论面部不对称患者其两侧关节盘的形态和功能存在不同程度的差异,关节内部结构紊乱与面部不对称畸形的关系有待进一步研究。     

Condylar movement analysis in subjects with clinically normal temporomandibular joints,utilizing an amorphous sensor

The purpose of this study was to determine the range of condylar movements in normal subjects, by the use of an amorphous sensor. The pair-matched sample consisted of 17 Caucasian males (aged 25.8 +/- 2.5 years) and 17 Caucasian females (aged 25.5 +/- 2.8 years) who had no subjective or objective symptoms related to temporomandibular joint (TMJ) sounds. Bilateral condylar and jaw movements were recorded simultaneously. The results showed that the typical condylar movement points plotted on the X-Y coordinates indicated a uniform or approximately straight line, that is X = Y. The mean +/- standard deviation (s.d.) for the maximum velocity of condylar movement during the opening and closing phases was 32.6 +/- 16.9 and 39.8 +/- 21.5 mm s-1, respectively. The mean +/- s.d. for the degree of jaw opening at the turning point of condylar movement was 36.9 +/- 21.7%. Significant correlations existed between any two measurements of maximum velocity of condylar movement. Moreover, significant correlations existed between the left and right sides in the degree of jaw opening at the turning point of condylar movement. These results suggest that a range of normal values of condylar movements can be developed when utilizing the amorphous sensor method.     

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.     

颞下颌关节盘前移位关节间隙改变的X线研究

目的测量颞下颌关节盘前移位患者与健康成人许勒位片上的关节间隙,分析髁突在关节窝中的位置,探讨髁突后移位在关节盘前移位临床诊断中的价值。方法选择120例（120侧）关节盘前移位患者和30例健康成人,拍摄许勒位片,使用AutoCAD计算机软件,采用2种线距测量方法（张震康法和Kamelchuk法）在许勒位片上测量关节间隙,并计算ln（P/A）值,比较关节盘前移位患者与健康成人（对照组）关节间隙的差异。结果2种测量方法的测量结果均显示：关节盘前移位组的关节上间隙和后间隙均小于对照组,其差异有统计学意义（P<0.05）,而关节前间隙与对照组的差异无统计学意义（P>0.05）;关节盘前移位组ln（P/A）值均小于对照组相应ln（P/A）值,其差异有统计学意义（P<0.05）。结论许勒位片上显示的颞下颌关节髁突后移位在一定程度上提示有关节盘前移位的存在;但正常髁突位置也存在变异,单纯的许勒位片尚不能作为关节盘前移位的确切诊断依据。     

Temporomandibular joint abnormalities and bite force in a group of adults with rheumatoid arthritis

Maximal mouth opening, translatory condylar motion (radiographically assessed) and bite force in sixteen adults with rheumatoid arthritis and radiographic temporomandibular joint abnormalities were compared with data from sixteen individuals without joint disease. Mean mouth opening in the arthritis group was reduced, but not statistically significant. Condylar translation and bite force showed significantly lower values than in the healthy individuals. Maximal mouth opening seemed to be the most uncertain parameter for the estimation of jaw function. In seven patients with a normal mouth opening (40-46 mm), both the condylar translation and the bite force were significantly impaired.     

Stereometric assessment of TMJ space variation by occlusal splints

Occlusal splints are used for the management of temporomandibular disorders, although their mechanism of action remains controversial. This study investigated whether insertion of an occlusal splint leads to condyle-fossa distance changes, and to mandibular rotation and/or translation. By combining magnetic resonance images with jaw tracking (dynamic stereometry), we analyzed the intra-articular distances of 20 human temporomandibular joints (TMJs) before and after insertion of occlusal splints of 3 mm thickness in the first molar region. For habitual closure, protrusion, and laterotrusion in the contralateral joint, occlusal splints led to minor--yet statistically significant--increases of global TMJ space and to larger increases at defined condylar areas. Condylar end rotation and translation in habitual closure were reduced. Hence, the insertion of a 3-mm-thick occlusal splint led to a change in the topographical condyle-fossa relationship, and therefore to a new distribution of contact areas between joint surfaces.     

Influence of friction at articular surfaces of the temporomandibular joint on stresses in the articular disk: a theoretical approach with the finite element method

The present study was designed to assess stress and displacement of the temporomandibular joint (TMJ) disk during jaw opening with different frictional coefficients (micro) from 0.0001 to 0.5 at the TMJ disk and bony component interfaces using three-dimensional finite element (FE) models of individual TMJs based on magnetic resonance (MR) images. An asymptomatic female volunteer and a female patient with anterior disk displacement without reduction were selected, and serial sagittal and frontal slices of their MR images were used for the TMJ reconstruction procedure. The condylar movement was recorded during jaw opening by a Gnatho-hexagraph and used as the loading condition for the subsequent stress analysis of the model. In the asymptomatic subject, relatively high von Mises stresses were observed in the anterior and lateral regions of the disk during jaw opening, and the superior boundary, contacting with the glenoid fossa, exhibited lower stresses than those on the inferior boundary facing the condyle. In the symptomatic subject, although the stress value in the disk was relatively low, the posterior connective tissue exhibited high stress throughout jaw opening. Additional increments in stress values and disk displacement were observed as the coefficient of friction increased, especially in the asymptomatic subject. It is concluded that an augmentation in the friction between the disk, glenoid fossa, and condyle produces an increment in stress and displacement of the disk.     

Correlation between computer-assisted measurements of mandibular opening and closing movements and clinical symptoms of temporomandibular dysfunction

197 subjects (74 male, 123 female) were evaluated in this Study of Health in Pomerania associated project (SHIP 0). Both a clinical functional status and an instrumental analysis of functional movement patterns of the mandible were performed in each subject, in the latter case using an ultrasonic jaw motion analysis system. Correlations between instrumental movement pattern features and clinical signs and symptoms of temporomandibular joint dysfunction (TMD), such as joint sounds, palpable impairment of jaw movement, and the termination of opening movement at the incisal point, were particularly significant (p <0.005). Correlations for TMJ crepitation sounds and joint pain on palpitation from the lateral or posterior aspect tended to be less significant (p < 0.1). No association was found for pain on jaw movement or muscle tenderness in response to pressure. A multivariate logistic regression model showed a significant correlation between Helkimo Clinical Dysfunction grades 2 and 3 and the following independent variables: frequent headaches (odds ratio [OR] 4.12; p = 0.032), frequent popping sounds in the jaw joints (OR 5.79; p = 0.012), incisal paths showing conspicuous signs of dysfunction such as deviation or deflection (OR 4.35; p = 0.05), and condylar path anomalies such as jumpy, straight/inverse or irregular tracings (OR 28.59; p = 0.006). Instrumental functional analysis of condylar path tracings allows one to draw statistically valid conclusions about the occurrence of TMD symptoms. It can be helpful to perform condylar path analysis when performing risk assessments for temporomandibular dysfunction in certain situations, particularly before prosthetic rehabilitation.     

联合动态MRI和下颌运动轨迹描记仪分析健康人开闭口时下颌运动轨迹特征

目的：结合动态MRl分析健康人开闭口时下颌运动轨迹特征。方法：18例健康人最大开闭口过程进行动态MRI和下颌运动轨迹描记仪检查，分析髁状突及下颌前牙切点的运动特点及范围。结果：动态MRI显示闭口位关节盘本体部呈双凹形，本体部位于髁状突横嵴的前方（盘分界角〈10。）。健康人下颁前牙切点运动轨迹平滑，双侧运动中心运动轨迹左右对称；运动轴始终保持平行，呈现开闭口初、末时密度比开闭口中时大；运动中心运动距离（13．2±3．1）mm，切点运动距离（41．1±3．8）mm。结论：下颌运动轨迹描记能记录髁状突运动轨迹并且间接反映颞下颌关节的关节盘在开闭口运动中的位置变化情况，为初步建立下颌运动轨迹描记对辅助诊断关节病的参考标准奠定了基础。     

Relationship Between Sagittal Condylar Path and the Degree of Mandibular Asymmetry in Unilateral Cross-Bite Patients

This study was conducted to investigate the relationship between sagittal condylar path and the degree of mandibular asymmetry during jaw opening movement in subjects (25 adults: 7 males, 18 females) with unilateral cross-bite. The degree of mandibular shift was measured with the axial projected head plate. Sagittal condylar path was obtained by CADIAX. The shifted side of the condyles had a steeper condylar path than that observed on the ipsilateral side. There was no correlation between the deviation of the forward component in the sagittal condylar path and the degree of mandibular asymmetry.