Movement Of Mandibular Condyle Research Articles

Surgical management of chronic temporomandibular joint dislocations.

Temporomandibular joint dislocation is described as the movement of mandibular condyle out of the fossa beyond its anatomical and functional boundaries causing pain and discomfort. It is often managed by conservative methods, but in long-standing, chronic conditions, surgical treatment is the only option. The goal of surgical treatment is to reposition the condyle and prevent further recurrences. This retrospective analysis involving a single center and a surgeon with 19 patients and 23 joint surgeries performed over a 10-year period. Patients who fulfilled inclusion and exclusion criteria and had earlier undergone surgical correction with hook-shaped miniplates and miniscrews fixed with or without bone grafts formed the study group. In all, 12 were female (mean age, 41.9 ± 12.07 years) and the rest 9 were male (mean age, 39.8 ± 13.6 years), ranging from 32 years to 58 years. All patients had the dislocation for an average period of 19.26 ± 12.6 months before the surgery. The mean maximal mouth opening (without pain) preoperatively was 17.78 ± 2.13 mm (12-25 mm) while postoperatively it was 32.28 ± 3.17 mm (27-37 mm). There were no immediate or late surgical complications in the follow-up period that ranged from 8 to 37 months. When proper case selection is employed and properly done, using hook-shaped miniplates with or without bone graft is more cost-effective, giving excellent short- and long-term effects. The results in this Indian population are very similar to that reported from other parts of the world.

Diurnal Difference between Mandibular Condyle Movement with Unilateral Temporomandibular Joint Clicking in the Morning and that in the Evening

Diurnal Difference between Mandibular Condyle Movement with Unilateral Temporomandibular Joint Clicking in the Morning and that in the Evening

A case of reformed coronoid process and mandibular angle after coronoidectomy and anglectomy for masticatory muscle tendon-aponeurosis hyperplasia

Masticatory muscle tendon-aponeurosis hyperplasia is a newly defined disease entity in Japan, in which limited mouth opening results from limited masticatory muscle extension caused by hyperplasia of the tendon and aponeurosis. Recently, we encountered a rare case of reformed bilateral coronoid process and mandibular angle after coronoidectomy and anglectomy. A 19-year-old female with gradually progressive trismus had been diagnosed with this disease. Under general anesthesia, she received coronoidotomy of the bilateral coronoid process and anglectomy. At 1 week postoperatively, trismus was improved. At 6 months postoperatively, panoramic imaging showed the initiation of bilateral reformed coronoid process and mandibular angle. At 3 years postoperatively, computed tomography (CT) and three-dimensional reconstructed CT (3D-CT) demonstrated reformed coronoid process and mandibular angle. However, the maximum mouth opening length was not decreased. She continued to perform mandibular condyle movement exercise every day. Panoramic imaging is a very useful examination for evaluating bone reformation after coronoidectomy and anglectomy for masticatory muscle tendon-aponeurosis hyperplasia. In particular, CT and 3D-CT demonstrated reformed coronoid process and mandibular angle. Postoperative mouth-opening training is an important prognostic factor to prevent the recurrence of trismus in this disease.

Movement of the mandibular condyle and activity of the masseter and lateral pterygoid muscles during masticatory-like jaw movements induced by electrical stimulation of the cortical masticatory area of rabbits

We examined the functional role of the lateral pterygoid muscle (LP) and the masseter muscle (MS) in the movement of the mandibular condyle in masticatory-like jaw movements induced by electrical stimulation of the cortical masticatory area of urethane-anaesthetised rabbits. EMGs of the LP and MS were recorded along with video images of the mandibular condyle movement filmed with a high-speed CCD camera at a time resolution of 8 ms. The time required for the contractile force of the MS and LP to emerge as bite force or jaw movement was determined by direct electrical stimulation to respective muscles: 32.8 ± 1.5 ms for the MS and 34.3 ± 2.9 ms for the LP. The LP on the working side showed biphasic activity not only in the jaw-opening phase but also in the middle occlusal phase. It is assumed that the MS on the working side begins to exert actually the maximum mechanical influence on the bite force 32.8 ms after its EMG peak in the early occlusal phase. Such development of the mechanical effect of the MS during middle occlusal phase is appeared to be involved in stabilization of the condyle in the middle occlusal phase. Approximately 25 ms (25.1 ± 2.5 ms) after the peak of mechanical influence of the MS, the mechanical influence of the working-side LP activity reached maximum in the late stage of the occlusal phase. This LP mechanical influence seems to be functionally associated with an antero-inferior movement of the working side condyle in the late stage of the occlusal phase that is coincident with a movement of the incisal point towards the balancing side across the midline.

Mandibular condyle movement during mastication of foods.

This study evaluated the mandibular condyle displacement on the working side while masticating certain foods with different textures. For referencing the mandibular condyle movement, the range of voluntary border movement of the mandibular condyle was determined based on the analysis of the sagittal, left lateral and right lateral border motion using Posselt's figure. The test foods consisted of cheese, peanuts, and beef jerky. During mastication of cheese and peanuts, the amount of displacement of the mandibular condyle in all directions was within the range of border movement. Significant posterior and superior shifts of the mandibular condyle were observed during mastication of beef jerky, compared with the findings obtained during border movement. Accordingly, it is suggested that prolonged mastication of hard fibrous foods, may stimulate the temporomandibular joint structure and mandibular dysfunction patients should limit their intake of such foods.

EMG activities of two heads of the human lateral pterygoid muscle in relation to mandibular condyle movement and biting force.

Electromyographic (EMG) activities of the superior (SUP) and inferior heads (INF) of the lateral pterygoid muscle (LPT) were recorded in humans during voluntary stepwise changes in biting force and jaw position that were adopted to exclude the effects of acceleration and velocity of jaw movements on the muscle activity. The SUP behaved like a jaw-closing muscle and showed characteristic activity in relation to the biting force. It showed a considerable amount of background activity (5-32% of the maximum) even in the intercuspal position without teeth clenching and reached a nearly maximum activity at relatively lower biting-force levels than the jaw-closing muscles during increment of the biting force. Stretch reflexes were found in the SUP, the function of which could be to stabilize the condyle against the biting force that pulls the condyle posteriorly. This notion was verified by examining the biomechanics on the temporomandibular joint. The complex movements of the mandibular condyle in a sagittal plane were decomposed into displacement in the anteroposterior direction (Ac) and angle of rotation (RAc) around a kinesiological specific point on the condyle. In relation to Ac, each head of the LPT showed quite a similar behavior to each other in all types of jaw movements across all subjects. Working ranges of the muscle activities were almost constant (Ac <3 mm for the SUP and Ac >3 mm for the INF). The amount of EMG activity of the SUP changed in inverse proportion to Ac showing a hyperbola-like relation, whereas that of the INF changed rather linearly. The EMG amplitude of the SUP showed a quasilinear inverse relation with RAc in the hinge movement during which the condyle rotated with no movement in the anteroposterior direction. This finding suggests that the SUP controls the angular relationship between the articular disk and the condyle. On the other hand, the position of the disk in relation to the maxilla, not to the condyle, is controlled indirectly by the INF because the disk is attached to the condyle by tendinous ligaments.

Three dimensional stress analysis of various directions of mandibular condyle movement using the finite element method

Three dimensional stress analysis of various directions of mandibular condyle movement using the finite element method

マルチストロボ装置を応用した下顎運動の研究 ア音発音時の下顎頭について

Many reports have been made by researchers in the past on the study of the mandibular movement, which is a matter of primary concern in prosthodontics. It has been made clear by these reports that the movements of mandibular condyle can be divided into two kinetic elements of translation and rotation. However, almost no report has been made so far concerning in what temporal process these two elements occur at the time of physiologic condyle movement, especially when phonation is made.Therefore, the author particulary took up the phonation of the [a:] sound, which is least influenced by occlusion and the vertical and horizontal overlap of the anterior. The author then paid attention to the movement of mandibular condyle when the [a:] sound was pronounced. And in order to serve for the diagnosis of dysfunction of the stomatognathic system, the subjects used for the present experiment were limited to those who had no abnormality in their stomatognathic system. By photographic analysis using a multiple stroboscope apparatus, and considering the time element, the author recorded and analyzed the translation and rotation of mandibular condyle, and reached the following conclusion.1) All the seven subjects tended to show very little difference in the amount of translation and the degree of rotation of their mandibular condyle, as well as in the time required until it came to the position ready to pronounce the [a:] sound.2) The amount of translation of mandibular condyle from the position of maximal intercuspal occlusion to that when the [a:] sound was ready to be pronounced was between 2.31 mm and 6.15 mm ; the degree of rotation was between 5.03°and 7.73°; and the time required was between 0.115 and 0.174 seconds.3) The amount of translation from the position of the maximal intercuspal occlusion to that when the mandibular movement stopped with the pronunciation of the [a:]sound was between 3.02 mm and 13.37 mm; the degree of rotation was between 6.42° and 12.81°; and the time required was between 0.194 and 0.326 seconds.4) When compared before and after the [a:] sound was pronounced, the rotation of mandibular condyle tended to occur earlier than translation.5) When comparison was made by dividing the entire movement of mandibular condyle into three periods, the speed of change, both in translation and rotation, tended to be quickest in the second period; as for rotation, the degree of rotation tended to be smaller in the third period compared to that in the first.6) From the result of the present research, it is presu med that the mandibular condyle first moves, featuring rotation, to a comparatively fixed position, and later moves, featuring translation, to the position most appropriate for the pronunciation of the [a:] sound.

Patterns of mandibular movement and jaw muscle activity during mastication in the monkey.

Patterns of mandibular movement and jaw muscle activity during mastication in the monkey.