Analysis of kinesiograph recordings and masticatory efficiency after treatment of non-reducing disk displacement of the temporomandibular joint

The purpose of this study was to clarify the kinesiographs of chewing movement and masticatory efficiency before and after treatment in patients with non-reducing disk displacement of the temporomandibular joint (TMJ). Twenty patients who were diagnosed with unilateral non-reducing disk displacement of the TMJ were treated with pumping of the joint with injection of sodium hyaluronate. Chewing movement patterns in these patients were evaluated, using mandibular kinesiography (MKG) at their initial visit and at mean 19-month follow-up and the results were compared. Masticatory efficiency was also measured. As controls, 23 volunteers without TMJ dysfunction were employed. Far from the results of normal volunteers, chewing movement patterns of the patients on MKG did not show deviation to the chewing side in the TMJ-unaffected-side chewing in the horizontal plane. However, such patterns of the patients became similar to those of normal volunteers after treatment. Masticatory efficiency of the patients improved after treatment, though it was impaired at initial visit. The MKG and masticatory efficiency test appeared to be a useful method of comparing masticatory function before and after treatment in patients with non-reducing disk displacement of the TMJ.     

Natural course of non-reducing disc displacement of the temporomandibular joint: changes in electromyographic activity during chewing movement

The purpose of this study is to examine whether electromyographic activity (EMG) during chewing movement changes towards the control level spontaneously in the subsequent course after diagnosis in patients with non-reducing disc displacement of the temporomandibular joint (TMJ) who do not receive any treatment. In 15 such patients, EMG data were examined at initial visit and at a mean follow-up of 21.7 months. As a control, 23 persons who had no TMJ dysfunction were studied. The results of EMG were compared among patients at initial visit, those at follow-up, and controls. The patients' clinical signs and symptoms were alleviated during the follow-up period. Duration of muscle contraction, cycle time and integrated EMG value (IEMG) at initial visit in patients were significantly different from those in the controls. In patients, IEMG for chewing-side masseter during chewing in the TMJ-affected side was greater at follow-up (14.2 +/- 8.01 microV s) than that at initial visit (10.5 +/- 3.69 microV s) (P < 0.05). In patients, duration of muscle contraction or cycle time at follow-up was not different from that at initial visit. Patients with non-reducing disc displacement of the TMJ showed spontaneous increasing of IEMG without any treatment in the subsequent course after diagnosis, coupled with improvement of clinical signs and symptoms. Duration of muscle contraction or cycle time did not change towards the control level. The results presented are useful as control data to understand the true effect of a particular treatment for patients with non-reducing disc displacement of the TMJ.     

Analysis of post-treatment electromyographs in patients with non-reducing disc displacement of the temporomandibular joint

The purpose of this study was to clarify the electromyographic property of chewing movement before and after treatment in patients with non-reducing disc displacement of the temporomandibular joint (TMJ). Twenty patients who were diagnosed with unilateral non-reducing disc displacement of the TMJ were treated by pumping and injection of sodium hyaluronate into the joint. Chewing movement in these patients was evaluated by electromyography (EMG) at the initial visit and at mean 19-month follow-up and the results were compared. Chewing movement in 23 normal controls were also examined. Duration of contraction, cycle time and integrated value at the initial visit which were different from those in the controls without TMJ dysfunction tended to be at the control level mean 19 months after treatment of pumping and injection of sodium hyaluronate into the joint in patients with non-reducing disc displacement of the TMJ. Electromyography appeared to be a method of documenting the chewing movement which was impaired at initial visit improved after treatment in patients with non-reducing disc displacement of the TMJ.     

Natural course of disc displacement with reduction of the temporomandibular joint: changes in clinical signs and symptoms.

PURPOSE: The goal of this study was to examine the natural course of disc displacement with reduction in the temporomandibular joint (TMJ). PATIENTS AND METHODS: This retrospective study involved 24 patients who had been diagnosed with disc displacement with reduction of the TMJ, but who had not undergone any treatment. The extent of maximal mouth opening, protrusion, lateral excursions, noise of the TMJ, pain of the TMJ, and tenderness of masticatory muscles were recorded monthly for a mean of 25.8 months. RESULTS: Maximal mouth opening, protrusion, and lateral excursions remained unchanged during follow-up. TMJ pain decreased by 15.7% (P >.05). Clicking decreased by 20.8% (P <.05), and tenderness of masticatory muscles decreased by 33.3% (P <.05). Reciprocal clicking remained unchanged in 19 patients (79.2%) and disappeared in 5 patients (23.8%). Four patients (16.7%) in whom clicking disappeared had a normal mouth opening, but locking developed in 1 patient (4.2%). CONCLUSIONS: In patients with disc displacement with reduction who do not undergo treatment, range of movement remains unchanged over time. Tenderness of masticatory muscles tended lessen, but reciprocal clicking and TMJ pain tended to remain. Clicking did not progress to locking in most patients.     

Clinical, radiographic, and electromyographic study of patients with internal derangement of the temporomandibular joint

Fifteen patients with internal derangement of the temporomandibular joint (TMJ) were examined clinically, radiographically, and electromyographically. Electromyographic recordings were also obtained from 11 subjects without signs or symptoms associated with their TMJs or masticatory musculature. All the patients with internal derangement demonstrated interferences on the ipsilateral side. This was interpreted as the result of disc displacement producing a reduced joint space and, consequently, a decreased vertical dimension on the symptomatic side. Slow opening and closing mandibular movements without clenching could be performed by healthy persons without noticeable EMG activity in the temporalis and masseter muscles. In association with disc displacement, electromyographic activity of the temporalis and masseter muscles occurred when the condyle slid over the posterior band of the disc and could be interpreted as an arthrokinetic reflex caused by distraction. Continuous muscle activity could be provoked by TMJ disc displacement and ceased when the disc position was normalized on mouth opening, only to occur again every time the disc became displaced on mouth closure. Anterior disc displacement without reduction (closed lock) could cause spastic activity in the temporalis muscle on the affected side. Spastic activity of the masseter and temporalis muscles occurring on the same side as a joint with anterior disc displacement hinders or inhibits the condylar movement necessary to achieve reduction.     

Movement of temporomandibular joint tissues during mastication and passive manipulation in miniature pigs

Movement is an important aspect of the biomechanics of the temporomandibular joint (TMJ). To track the relative movements of TMJ components, radio-opaque markers were implanted in the left squamosal bone, mandible and retrodiscal tissue of miniature pigs. Medial-lateral (ML) and dorsal-ventral (DV) fluoroscopic records were made 8-10 weeks later during chewing and passive manipulation. Marker movements were digitized from the videotapes. During passive manipulation, the deformation of the lateral capsule was also measured with a differential variable-reluctance transducer. The results provide new details about porcine chewing pattern, which is distinguished by a regularly alternating chewing side. During masticatory opening, the mandible had a centre of rotation (CR) well inferior to the condyle and close to the angle. In contrast, the passive opening movement showed a higher CR location close to the condylar neck, indicating a different motion from masticatory opening. The retrodiscal tissue followed the movements of the mandibular condyle during both mastication and passive manipulation. The lateral capsule elongated during ipsilateral shifts and retrusion, implying a possible role in limiting such movements. These movement characteristics provide a useful reference for studies on the TMJ using pigs.     

Mandibular movement and frontal craniofacial morphology in orthognathic surgery patients with mandibular deviation and protrusion

The present study was conducted to investigate the relationship between mandibular movement (lateral excursion and masticatory movements) and craniofacial morphology in 16 patients with mandibular deviation, using a six degrees-of-freedom measuring device. (i) Mandibular deviation was found to be significantly related to frontal maxillary and occlusal plane angles. (ii) Three-dimensional non-working condylar and incisal path lengths were longer during the lateral excursion to the non-deviated side than to the deviated side, and the incisal path moved antero-inferior. (iii) The lateral motion range of the incisal path was wider during masticatory movement on the non-deviated side than on the deviated side, and the molar and non-working condylar path lengths corresponding to the lateral range of the incisal path were also longer on the non-deviated side. The group with posterior crossbite showed a significantly smaller horizontal range of incisal path, and also significantly smaller frontal projected incisal and molar path angles during masticatory movement on the deviated side than on the non-deviated side. These results suggest that lateral excursion and masticatory movements could be related to craniofacial morphology and posterior crossbite.     

Movement of the lateral and medial poles of the working condyle during mastication in patients with unilateral posterior crossbite.

Patients with unilateral posterior crossbite often show reverse sequential jaw movement patterns on the frontal view during mastication on the crossbite side. Recent studies show that such patients are prone to suffer from temporomandibular joint (TMJ) disc displacement, particularly the lateral portion. The purpose of this study was to examine the movement of the lateral and medial poles of the working condyle during mastication in such patients. Subjects were 12 consecutive patients with unilateral posterior crossbites and without TMJ disc displacements and 12 normal subjects. An optoelectronic jaw-tracking system with 6 degrees of freedom was used to record the motion of the lateral and medial poles of the working condyle during mastication of standardized hard, gummy jelly. The data from the first 10 cycles were analyzed. The lateral and medial poles of the condyle on the crossbite side moved more in the medial direction and less in the lateral direction during mastication in the crossbite patients than the condyle in the normal subjects. The lateral pole of the working condyle moved more in the posterior and inferior directions and less in the anterior direction than the medial pole in all subjects. These results suggest that these condylar movements in patients with unilateral posterior crossbites might be related to the susceptibility to TMJ disc displacement, particularly the lateral portion.     

Disc position and morphology in patients with nonreducing disc displacement treated by injection of sodium hyaluronate.

Disc position and morphology were examined in 21 patients (22 joints) with nonreducing disc displacement of the temporomandibular joint (TMJ) at more than 12 months after undergoing injection of sodium hyaluronate into the superior joint space. The patients' clinical signs and symptoms improved during the follow-up period. In all patients, the disc was displaced anteriorly on mouth closure and did not reduce into the normal position during mouth opening at follow-up, whereas a normal disc position was found in all the controls. In the patients, the disc deviated from the normal biconcave configuration found in all of the controls on the follow-up magnetic resonance imaging (MRI). Disc displacement apparently is persistent and continued disc deformity common in patients, although the clinical signs and symptoms improved.     

Occlusal contact area, occlusal pressure, bite force, and masticatory efficiency in patients with anterior disc displacement of the temporomandibular joint

The occlusal contact area, occlusal pressure, bite force, and masticatory efficiency were measured in 48 patients with anterior disc displacement (ADD) of the temporomandibular joint (TMJ). The results were compared with those of 30 normal controls without TMJ dysfunction. The values of occlusal contact area, bite force, and masticatory efficiency measured in patients with ADD were significantly smaller than those measured in the controls, although there was no difference in occlusal pressure between the two groups. The results of the measurements of 22 patients with ADD with reduction were also compared with those of 26 patients with ADD without reduction. There was no difference in any measurement between these patients subgroups. The analysis of occlusal contact area, bite force, and masticatory efficiency appeared to be useful methods in documenting the fact that masticatory function was impaired in patients with ADD of the TMJ.     

颞下颌关节侧向咬合位与对刃位薄层塑化断面对照研究

目的:对比分析下颌对刃位、侧向咬合位颞下颌关节的运动解剖形态,为颞下颌关节病变提供解剖依据。方法:将8例新鲜尸头摆置成对刃位5例、下颌侧向咬合位3例,以颞下颌关节为中心,切割成8cm×8cm×10cm的标本块,利用生物塑化技术,制成斜矢状位、斜冠状位、轴位塑化断层标本共16套。下颌侧向咬合位工作侧、非工作侧关节形态改变与对刃位相对照。结果:下颌侧向咬合位工作侧,髁突在关节窝内向后、向上、向外移位,关节盘位置无变化,关节盘双板及后带受压;非工作侧,髁突向下、向前、向内侧移位,关节盘后带位置向下移位,无前移位,关节盘中带外侧位居上下关节面之间,明显受压变薄。结论:关节盘并非随髁突作同步同向运动。关节盘在髁突作滑动运动时发生移位;当转动运动、滑动运动复合出现时,关节盘发生移位;而在关节窝内发生的转动运动,关节盘不发生移位。     

Characteristics of rhythmic jaw movements of the rabbit

The jaw-movement pattern of the rabbit during chewing foods of different consistency was analysed. The basic movement trajectory on the frontal plane showed a crescent loop, irrespective of the food type. Difference in food consistency exerted only minor effects on the maximum gape, extent of lateral excursion and the chewing rate. These parameters of jaw movement and also the duration of a single masticatory cycle (TCL) appeared to change with physical properties other than the hardness of food. On the other hand, the number of chewing cycles in a masticatory sequence increased with increasing the hardness of food. The TCL ranged between 250 and 300 ms (frequency: 3.3-4 Hz). When a single masticatory cycle was divided into three phases (opening, closing and power phases), the TCL depended more on the duration of the opening phase than that of other two phases.     

Comparison of treatment efficacy between hyaluronic acid and arthrocentesis plus hyaluronic acid in internal derangements of temporomandibular joint

The aim of the study was to compare the effectiveness of hyaluronic acid (HA) injection and arthrocentesis plus HA injection for treating disc displacement with reduction (DDwR) and disc displacement without reduction (DDwoR). In this randomized clinical trial, patients were divided into 2 main groups: group I (DDwR) and group II (DDwoR). Sub-groups were made depending on allocated treatment: group Ia (arthrocentesis plus HA), group Ib (single HA), group Ic (control), group IIa (arthrocentesis plus HA), group IIb (single HA), and group IIc (control). The primary outcome variable was maximum pain on chewing, while maximum pain at rest, maximum non-assisted and assisted mouth opening, chewing efficiency, temporomandibular joint (TMJ) sounds, quality of life, treatment tolerability, and treatment effectiveness were secondary outcomes. The influences of individual study variables (gender, involved side, and duration of symptoms) on clinical outcomes were also examined. The study consisted of 116 TMJs of 90 patients (n = 45 in both main groups, TMJs = 58) aged 15–82 years. At the 6-month follow-up, improvement in all parameters, except for TMJ sounds, was recorded in all treatment groups, with no improvements in control groups. Notably, arthrocentesis plus HA showed superior improvement in chewing efficiency (p = 0.041) and quality of life (p = 0.047) of group I and quality of life (p = 0.004) in group II, compared to single HA. Furthermore, the duration of symptoms correlated with clinical outcomes. Both procedures successfully improved the symptoms of DDwR and DDwoR patients, but arthrocentesis plus HA injection seemed superior.     

Computerized ultrasonic axiographic evaluation of condylar movement in patients with internal derangement of the temporomandibular joint

Objectives:To evaluate condylar movement during lateral excursion in individuals with internal derangement of the temporomandibular joint (TMJ) using ultrasonic axiography.Materials and Methods:A total of 34 patients with internal derangement of the TMJ and 34 participants in the control group were examined. Mandibular functional movement was recorded by ultrasonic axiography. Three-dimensional condylar movement was measured in the working and balancing condyles.Results:Significant differences in condylar movement were found between the two groups. In the group with internal derangement of the TMJ, the three-dimensional linear distances of the condylar path in a working condyle were greater than in the control group during lateral excursion. The speed of the balancing condyle in the returning path of lateral excursion was significantly greater in the group with internal derangement than in the control group.Conclusions:The results of the present study indicate that internal derangement of TMJ may affect the working and balancing condylar movements during lateral excursion.     

The effect of food bolus location on jaw movement smoothness and masticatory efficiency

Masticatory efficiency in individuals with extensive tooth loss has been widely discussed. However, little is known about jaw movement smoothness during chewing and the effect of differences in food bolus location on movement smoothness and masticatory efficiency. The aim of this study was to determine whether experimental differences in food bolus location (anterior versus posterior) had an effect on masticatory efficiency and jaw movement smoothness. Jaw movement smoothness was evaluated by measuring jerk-cost (calculated from acceleration) with an accelerometer that was attached to the skin of the mentum of 10 asymptomatic subjects, and acceleration was recorded during chewing on two-colour chewing gum, which was used to assessed masticatory efficiency. Chewing was performed under two conditions: posterior chewing (chewing on molars and premolars only) and anterior chewing (chewing on canine and first premolar teeth only). Jerk-cost and masticatory efficiency (calculated as the ratio of unmixed azure colour to the total area of gum, the unmixed fraction) were compared between anterior and posterior chewing with the Wilcoxon signed rank test (two-tailed). Subjects chewed significantly less efficiently during anterior chewing than during posterior chewing (P = 0·0051). There was no significant difference in jerk-cost between anterior and posterior conditions in the opening phase (P = 0·25), or closing phase (P = 0·42). This is the first characterisation of the effect of food bolus location on jaw movement smoothness at the same time as recording masticatory efficiency. The data suggest that anterior chewing decreases masticatory efficiency, but does not influence jerk-cost.     

Advantages of intraoral verticosagittal ramus osteotomy in skeletofacial deformity patients with temporomandibular joint disorders.

PURPOSE: This preliminary study was performed to clarify the usefulness of intraoral verticosagittal ramus osteotomy (IVSRO) in patients with temporomandibular joint (TMJ) disorders. PATIENTS AND METHODS: We examined 34 sides in 19 consecutive patients with dentofacial deformities with TMJ dysfunction undergoing IVSRO. Preoperatively, 15 patients had TMJ sounds bilaterally and 4 had sounds unilaterally. Five sides in 3 patients had pain in the TMJ, and 4 sides in 3 patients had masticatory muscle pain. The TMJ symptoms, including TMJ sounds, pain in the TMJ, and masticatory muscle pain in each patient, were assessed clinically before and approximately 12 months after IVSRO. Magnetic resonance imaging was also performed to determine joint status, including determination of the positions of the condyle and disc. RESULTS: The symptoms of the TMJ after 12 months of orthodontic treatment showed marked improvements, with the disappearance of the TMJ sounds in 94% of the sides examined. Pain in the TMJ improved in 4 of 5 sides, and pain of the masticatory muscle improved in 3 of 4 sides. With regard to the relative positions of the condyle and disc on magnetic resonance imaging, 6 of 8 joints and 5 of 7 joints showed improvement in anterior disc displacement with and without reduction, respectively. The direction and mean amount of movement in the distal segment were 8 mm in setback, 4 mm in advance, and 5 mm counterclockwise. CONCLUSION: IVSRO is potentially as useful for the treatment of TMJ disorders in orthognathic surgery patients as is intraoral vertical ramus osteotomy, and IVSRO can be used selectively in cases in which intraoral vertical ramus osteotomy is contraindicated.     

Examination of the diagnostic value and estimation of the chaos phenomenon in masticatory movement using fractal dimension in patients with temporomandibular dysfunction syndrome

The aim of this study was to estimate the chaos phenomenon (chaos) in masticatory movements using the fractal dimension (FD), and to examine the diagnostic value of the fractal dimension in comparing stomatognathic functional disturbances with normal stomatognathic function. The subjects were all high school students and included nine subjects presenting with acceptable normal occlusion, 18 subjects with TMJ dysfunction syndrome and seven subjects with tooth crowding. Masticatory movements were obtained during free, right side, and left side gum‐chewing and were used to calculate the capacity dimension in the FD. Chaos in the masticatory movement was estimated by the FD saturated with some constant value to an increase of embedding dimension (approached a plateau). In the crowding group, the FD was also significantly high on the sagittal plane in comparison with the normal. In the patients with pain, the FD on the sagittal plane was significantly high. In the patients with pain and closed lock, the FD on the frontal plane was significantly high. However, in the patients with pain and with reduction of anterior disc displacement, the FD was significantly low on the horizontal plane. These findings suggest that chaos is present in masticatory movements and the difference in the FD are of diagnostic value in evaluation of the relationship between FD and stomatognathic functional disturbance.     

Clinical study on the relationship between chewing movements and temporomandibular joint abnormalities

Chewing movements are accomplished by the harmonious function of the stomatognathic system. Therefore, TMJs play important roles in chewing movements. Recently, significant findings on TMJ abnormalities have been obtained from many studies. However, the relationship between chewing movements and TMJ abnormalities remains unclear. The purpose of this study was to examine how TMJ abnormalities were reflected in chewing movements. Incisor point movements during chewing (chewing pattern) were investigated in 150 abnormal and 25 normal subjects using Sirognathograph Analysing System. Abnormal subjects were composed of 45 patients with anterior disk displacement with reduction (reciprocal click), 20 patients with anterior disk displacement without reduction (closed lock), 50 patients with osteoarthrosis and 35 patients with MPD syndrome. Analysis of condylar movements during chewing were also performed in 9 normal and 20 abnormal subjects. The results were as follow; 1. Subjects with TMJ abnormalities tended to show abnormal chewing patterns when chewing at their non-abnormal sides. 2. TMJ abnormality of each different type tended to show its respective characteristic chewing pattern. 1) Subjects with osteoarthrosis and reciprocal click without condylar posterior dislocation tended to show deviation of the turning point to the non-chewing side, with a convex opening path in the frontal plane and a lack of anteroposterior width in the sagittal plane. This finding was associated with the limitation in movement of the abnormal-side condyle. 2) Subjects with reciprocal click with condylar posterior dislocation tended to show a concave opening path and reversed or cross-over patterns in the frontal and horizontal planes, respectively. This finding was associated with the movement of the abnormal-side condyle in the medio-anterior direction during the initial phase of opening. 3) Subjects with closed lock without condylar posterior dislocation tended to show deviation of the turning point to the non-chewing side, with a concave opening path in the frontal plane and a lack of anteroposterior width in the sagittal plane. This finding was associated with the severe limitation in movement of the abnormal-side condyle. 4) Subjects with closed lock with condylar posterior dislocation characteristically tended to show reversed or cross-over patterns in the horizontal plane. This finding was associated with the movement of the abnormal-side condyle in the medio-anterior direction during the initial phase of opening. However, this movement was smaller than that of the reciprocal click. 3. Subjects with MPD syndrome showed chewing patterns similar to those of normal subjects. From the results, close relationships were found between chewing movements and TMJ abnormalities.     

Temporo-mandibular joint kinetics and chewing cycles in children. A 3-year follow-up

Summary. Objectives. To report the temporo‐mandibular joint (TMJ) kinetics and masticatory function in healthy children. Design. Temporo‐mandibular joint palpation and electrognathographic registrations of chewing cycles were repeated for 3 years in order to evaluate changes. Setting. Healthy children without systemic pathologies, decayed cavities and previous dental treatment. Sample and methods. Electrognathographic (EGN) registration of masticatory cycles and TMJ palpation were carried out on 52 patients (mean age: 5 years 8 months, range: 5 years 1 month, 6 years 8 months), by two university researchers, once a year for 3 consecutive years. TMJ palpation, differentiated TMJ synchronism (simultaneous bilateral opening movement) and TMJ asynchronism (not simultaneous bilateral opening movement), TMJ subluxation and click were observed. Electrognathographic registrations differentiated normal and abnormal jaw chewing cycles, and narrow and large cycles. Results. Temporo‐mandibular joint asynchronism was evident in 34 of 52 patients in the primary dentition, in 42 of 52 patients after the eruption of the first permanent molar, and in 31 of 52 patients after the eruption of the permanent incisors. TMJ subluxation increased during the full period of observation. Three temporomandibular clicks appeared after the eruption of the permanent incisors. Altered mastication was not always associated with TMJ disorders. Conclusions. In children, normal chewing cycles can coexist with occlusal discrepancies, cranio‐facial growth and TMJ alterations.     

Electromyographic and kinesiographic study in patients with nonreducing disk displacement of the temporomandibular joint

ObjectivesThe purpose of this study was to clarify electromyographic and mandibular kinesiographic properties of the chewing movement in patients with unilaterally painful nonreducing disk displacement of the temporomandibular joint.Study designsChewing movement in 50 female patients was evaluated by electromyograph and mandibular kinesiograph, and the results were compared with those in 31 normal controls.ResultsIn the analysis by electromyograph, some differences between patients and controls were found. In the analysis by mandibular kinesiograph, chewing movement showed deviation to the chewing side in the TMJ-affected-side chewing but did not show deviation in the TMJ-unaffected-side chewing in the horizontal plane. The maximal anteroposterior width between opening and closing paths in the sagittal plane was smaller in the experimental subjects.ConclusionsThese differences between patients and controls may be helpful to diagnosis for painful nonreducing disk displacement of the temporomandibular joint.