The primary diagnosis of closed lock of temporomandibular disorders defined by the subjective symptoms of both the limitation of mouth opening and the click just before the limitation was studied. The patients of closed lock were divided into two types, type A was closed lock which had the subjective symptoms of both the limitation of mouth opening and the click just before the limitation, type B was the other closed lock. Further, type B was classified into three types. Type B1 had the subjective symptoms of the limitation of mouth opening but not the click just before the limitation. Type B2 had the subjective symptoms of the click just before the limitation but not the limitation mouth opening. Type B3 had the subjective symptoms of neither the limitation of mouth opening nor the click just before the limitation.
The sensitivity of primary diagnosis of closed lock of temporomandibular disorders in 251 patiens and clinical findings at the initial visit, which included maximal mouth opening, sounds of TMJ and radiographic bone changes, and clinical results in each type were investigated.
The results were as follows;
(1) The sensitivity of primary diagnosis of closed lock of temporomandibular disorders was 80.1 %.
(2) The incidence of maximal mouth opening of more than 40mm in patients of type A was significantly lower than type B (p<0.01), and especially lower than types B2 and B3.
(3) The incidence of sounds of TMJ in patients of type A was significantly lower than type B (p<0.01), and especially lower than types B2 and B3.
(4) The incidence of radiographic bone changes of the mandibular condyle in patients of type A was significantly lower than type B (p<0.01).
(5) The incidence of unlocked patients in type A was significantly higher than type B (p<0.01).
In conclusion, the primary diagnosis by the subjective symptoms of both the limitation of mouth opening and the click just before the limitation seemed to be a useful clinical diagnosis of closed lock expected reduction of the disk.

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The correlation between the temporomandibular joint sounds and MR image findings on anterior disc displacement without reduction was studied.
Materials and methods: The diagnosis of anterior disc displacement without reduction in 277 joints was made using MR images. These joints did not show drastic osseous changes on the condylar head and glenoid fossa. MR image findings were used as follows: (1) configuration of the disc; (2) degree of anterior disc displacement; (3) position of the condylar head; and (4) movement of the condyle.
Results: One hudred one joints (36%) had TMJ sounds (click and crepitus). The configuration of the disc was biconcave in 55% of the joints with clicking. The moderate anterior disc displacement was found in 66% of the joints with clicking. The position of condyle was not related to the TMJ sounds. In joints with clicking, their maximum opening was larger than joints without sounds.
Conclusion: The prevalence of biconcave disc, moderate displacement, and no limited range of opening was higher in the anterior disc displacement without reduction with temporomandibular joint sounds.

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The purpose of this study was to develop a system for measuring TMJ movement and vibration, compare the amplitude of TMJ movement, and evaluate the spectral properties of TMJ vibration.
The measuring device consisted of a noncontact sensor with amorphous - wire core multivibrators and small magnet. Data were obtained from one subject who had no symptoms of TMJ dysfunction and two subjects with TMJ sounds found by palpation. When measuring TMJ movement, the TMJ sounds were measured with condenser microphones, and mandibular movement was measured with MKG and muscle activity with EMG simultaneously. The timing between the right and left TMJ movement was quantified by means of Lissajous' figure.
From the three measurements with the same normal subject, the reproducibility of the system was confirmed. The results of this study showed that for the normal subject, Liss ajous' figure was smooth and a significant peak of energy was not found. On the other hand, for the subjects with TMJ sounds, Lissajous' figures were distorted and the primary band of energy was centered below 50Hz.
These results suggested that the evaluation of TMJ movement and vibration measured with amorphous sensor could be a method for TMJ function analysis.

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A questionnaire survey and/or revisitation of 86 juvenile temporomandibular disorder patients that visited our department from Jan. 1988 to Dec. 1989 was conducted.
Those under 16 years old were used in this study. Fourty-nine answers were given including those of 14 patients that revisited our clinic.
The items in the questionnaire were as follows:
Pain of the joint and/or muscles, and its degree.
The charactor of the TMJ noise and its change after treatment.
The mouth opening range.
The amount of satisfaction.
Thirty-eight patients had pain at the first visit, and 23 patients had pain in the survey and most of them answered “light pain” (18 patients). At the time of revisit, however, all 14 patients complained of slight or no pain.
Fourty-one patients answered “have joint noise” in the survey, and three of these patients answered “have aggravated noise” compared with those at the first visit.
Sixteen patients had a limited mouth opening range of less than 40mm, and 33 patients were able to open the mouth over 40mm at the first visit. In the survey, however, 48 patients were able to open their mouth over three QFB. All revisit patients showed no limited opening of less than 40mm. Most of the surveyed patients were considered to have gained better functional abaptability except for two patients having condyles showing bone change on the X-ray film at revisit. Although the majority of complains were associated with joint noise, there were few complaints associated with disabilities of joint function.

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Accurate measurement of the condylar position is important for diagnosis and treatment of temporomandibular joint (TMJ) dysfunction. Radiography has been used for this purpose, and recently, Scanora^® multimodal radiography was introduced to Showa University. The projection capacity of Scanora^® in TMJ is still unclear. The purpose of this study was to examine the projection capacity of a section of the target on sagittal tomography to evaluate the condylar position with Scanora^®. Four TMJs obtained from dried skulls were used. Dried skulls were placed on the head stabilizing device and the light beams were positioned on the skulls. Sagittal tomography was performed using the program numbers determined by corrected angles, an interj pint distance and a slice thick ness/distance. These angles were determined by lateral orientation zonography and the submental vertex projection in each TMJ. Images were obtained from sagittal tomography of dried skulls which were placed on the head stabilizing device; this device was repositioned three times and light beam positioning was repeated. The images were evaluated by projection grade by an author (T. H.). The results were as follows: 1) The sagittal tomograms of each layer occasionally differ in the number of projections, however, a section of the target was projected in four layers. 2) When the positioning of the light beam was repeated, the sagittal tomograms of each layer were approximately the same. 3) There was not much difference in the corrected angles.
The results indicated that sagittal tomography on Scanora^® is useful for determining condylar position, and the head stabilizing device requires improvement in order to decrease the difference of each layer of the sagittal tomograms.

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One patient who visited our hospital with the chief complaint of trismus was treated for Klippel-Feil syndrome.
This syndrome is a congenital disease characterized by synostosis of the cervical vertebrae and shortening of the cervix. In this syndrome, even a mild trauma can easily damage the spinal cord, so TMD patients must be treated without placing a burden on the cervical vertebra.
As approximately 7% of patients with this syndrome have cleft lip, and alveolus and palate, it was considered necessary to note the presence of this syndrome in treating TMD patients with cleft lip, alveolus, and palate.

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The purpose of this study was to investigate the relationship between the etiologic factors such as gender, age, and general joint mobility and TMJ disorders. Subjects comprised of 110 randomly selected orthodontic patients (78 females and 32 males) aged 9-37 years with a mean of 22.1 years. Joint mobility was assessed and graded by means of the hypermobility score of Beighton et al. Fifty of 78 females and 17 of 32 males showed the symptoms of TMJ disorders (symptomatic patients). TMJ sound was observed in every symptomatic patient. Relative risks- the incidence among the subjects in a particular category of exposure divided by the corresponding rate in the comparison category- for TMJ disorders associated with specific factors were adjusted for potentially compounding factors by logistic-regression analysis. No significant gender difference was observed in the prevalence of TMJ disorders. However, TMJ and muscular pain and difficulty in mouth opening were more frequently observed in female symptomatic patients than male patients. There was a significant relative risk of TMJ disorders associated with increasing age (relative risk, 1.28; P<0.001). Higher score of general joint mobility was also significantly associated with an increased risk of TMJ disorders (relative risk, 1.40; P=0.02).

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In this study, mandibular movement was measured in six degrees of freedom with a new analyzing system for stomatognathic functions. Incisor and bilateral condylar point movements were investigated in 20 normal subjects.
The results were as follows
1. At the incisor point, 11 subjects showed typical movement pattern, and 9 subjects showed other movement patterns.
2. At bilateral condylar points, 14 subjects showed typical movement pattern, and 6 subjects showed other movement patterns.
3. Only 7 subjects showed typical movement pattern at both incisor and bilateral condylar points.
From the results, the relationship between incisor and bilateral condylar point movements are not always paired.

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The purpose of this study was to investigate the macroscopic appearance of structural changes in the human temporomandibular joint and their potential relationship to occlusal parameters. The right and left temporomandibular joints were removed from 206 male cadavers (mean age: 66.1 years, range of age: 34-94 years). Only cadavers with known diseases capable of influencing joint tissues were excluded. The dentitions of each cadaver were classified into one of four types; type A: complete or almost complete set of teeth with bilateral molar support, type B: slight loss of teeth, reduced dentition only with molar support or anterior contact, type C: considerable loss of teeth, reduced dentition without molar support, and anterior contact, and type D: edentulous, with or without complete dentures. Structural changes in the condyle and disc components were classified by placing them into one of three grades; grades 0, 1, and 2, according to a modification of principle of Byers et al (1970). Their dentitions and structural changes of TMJ were evaluated by co-workers. A Mann-Whitney U-test was used for comparison among the four types. The results were as follows: (1) The structural changes of condyles in types A, B and C showed statistically lower scores than in type D (p<0.05). (2) There was a significant difference in the structural changes of discs between types A and C (p<0.01), between types A and D (p<0.01), and between types B and D (p<0.05). These results suggested that the macroscopic structural changes of the condyle were related to specific classifications of dentition.

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Deformity of the mandibular condyle is common in elderly patients with temporomandibular disorders (TMD), and it occurs more frequently in women than in men. Osteoporosis is a systemic bone metabolic disease affecting all bone in the body including the mandible.
In this study, skeletal bone mineral density (BMD) was measured by DEXA and the atrophic level of spine was evaluated by lateral lumber radiographs in 22 postmenopausal patients with TMD. These examinations revealed that over half of the patients suffered from osteoporosis. Then the deformity of the mandibular condyles was examined, and the relationship between their deformity and the number of missing teeth, and oral habits was investigated. The results were as follows
(1) Twenty of 22 patients had deformed condyles: erosion in 9, osteophyte in 3, and flattening, increasing of the cortical bone thickness, sclerosis, and abnormality of condyle form (deformity in a narrow sense) in 2 cases respectively.
(2) Lumber spine BMD of the patients with condylar deformity was lower than that of the patients without condylar deformity.
(3) Mean number of missing teeth (not including third molars) in the patients with condylar deformity was lower than that in the patients without condylar deformity, but no significant difference was found.
(4) Seven of 21 patients had a habit of grinding their teeth, and 14 patients had a habit of clenching. The majority of the patients with severe condylar deformity had a habit of clenching.

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Although the clinical signs and symptoms in patients with closed lock improved, posttreatment images showed that the discs remained displaced. In such a temporomandibular joint, pseudodisc formation of the posterior disc attachment (PA) has been hypothesized on the basis of findings in previous histopatholigical studies. However, there are few clinical data on this pseudodisc.
The purpose of this study was to examine whether pseudodisc formation occurs in a joint with good prognosis despite the disc remaining displaced. Twenty-five joints (23 patients) that were successfully treated with a nonsurgical treatment were included in this study. The patients underwent treatment in a step fashion as follows: 1) mandibular manipulation, 2) pumping manipulation, arthrocentesis, or anterior splint therapy assisted manipulation, and 3) stabilization splint therapy. The sagittal closed-mouth T1-weighted SE images (1.5 Tesla) were used to determine the signal intensity of the PA. Comparison of signal intensity of the PA before and after treatment was made.
In 19 joints with high signal intensity of the PA before treatment, only one joint showed low signal intensity suggesting pseudodisc formation after treatment, whereas the remaining 18 joints showed persistent high signal intensity. In 6 joints with low signal intensity of the PA before treatment, 2 joints showed low signal intensity after treatment, whereas the remaining 4 joints showed high signal intensity. There was no significant association between the changes in the signal intensity of the PA and the improvement in joint pain and dysfunction.
Therefore, the results suggested that the improvement of signs and symptoms is not necessarily accompanied by pseudodisc formation of the PA.

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The effects of lavage manipulation technique on closed lock patients was evaluated.
The subjects were 3 males and 23 females of aged 13 to 63 years (average, 29.5 years). The subjects had an average closed lock period of 14.2 months and no improvement by onservative treatment for 2.6 months, on average. The procedure was as follows: 18-gauge and 22-gauge needles were inserted into the superior articular cavity to lavage with 200 to 400ml of saline by applying pressure with a finger. Then sodium hyaluronate (ARTZ^®) and betamethasone (Rinderon^®) were injected in the superior articular cavity of the TMJ. After the needles were removed, manipulation was carried out to finish the operation. At 1 week, 1 month, and 3 months after the operation, clinical symptoms were investigated. MRI examination of each subject was also carried out paying attention especially to disk form. The results were as follows: (1) Both maximal mouth opening (MMO) and visual analog scale improved during the 3-month postoperative period. At 3 months after the operation, the effectiveness on 26 patients was 69.2% (2) As for MMO, the deformed disk cases showed higher effectiveness.

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Fractures of the condyle are not uncommon among various types of mandibular fracture, but a longitudinal fracture of the condyle is rarely seen. Recently, a case of longitudinal fracture of the condyle was treated by mandibular forward traction and arthroscopic surgery.
The patient, a 68-year-old male was referred to our clinic by an orthopedic clinic. In the first examination, the lower jaw was receded and TMJ double contrast CT showed a longitudinal fracture with displacement of condylar medial fragments and traumatic changes in the joint cavity.
The treatment was arthroscopic surgery of articular disk fixation after mandibular traction for approximately a month. One year four months after treatment, the function of the jaw was excellent.

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The purpose of this study was to investigate the short-term effects of muscle relaxant (Eperizone hydrochloride) and myomonitor on the silent period (SP) in patients with myogenous temporomandibular disorder. The SP elicited by mandibular tapping movement and tapping the chin were recorded electromyographically from the bilateral masseter and temporal muscles in patients with temporomandibular disorder and unilateral masseter muscle pain or tenderness (11cases). The SP latency on the affected side was not different from that on the unaffected side. The SP duration of the masseter and temporal were shorter on the affected side. After administration of this agent and myomonitor, the duration on the affected side was prolonged and the side asymmetry was shortened.

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In order to inrestigate the correlation between temporamandibular joint signs and symptoms and oral conditions, including occlusion, of the elderly 61 persons over 80 years old with more than 20 teeth were examined.
The results were as follows:
(1) Twenty-two persons (36.9%) had temporamandibular joint sounds. However, none had subjective symptoms of temporomandibular joint sound.
(2) Fifteen persons (24.6%) showed morphological bone changes of the condyles.
(3) One male had the subjective symptom of limitation of mouth opening and another male had the subjective symptom of pain of the masseter.
(4) Temporamandibular joint sounds were dosely associated with female, loss of molar teeth, and loss of bilateral second molar tooth in that order by multivariate analysis.
(5) The morphological bone changes of the condyles were closely associated with female by multivariate analysis.

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A clinical study was carried out to clarify clinical findings and treatment of elderly patients with temporomandibular disorders (TMD). Twenty-eight patients with TMD, aged over 65 years, mean: 69.8 years, were examined, and the clinical findings, including chief complaint, duration until first examination, range of motion, joint sound, and number of remaining teeth, X-ray findings, and treatment were compared. Patients of the same age without complaint of TMD were compared as controls. Pain was the most common chief complaint (71%). Most of the patients showed improvement spontaneously follwed by recurrence of signs/symptoms repeatedly for long periods. Though the patient complained of pain in the buccal region, pain was proved to be in the intracapsule by movement of manipulation. Numerous teeth of the patients were in good condition, but most teeth were treated. Closed lock was clinically diagnosed in most of the patients. X-ray findings showed flattening of condyle mostly, but the relationship between the pathogenesis of TMD and X-ray findings was anclear. Active exercise of TMJ and occlusal treatment were combined to enhance the effectiveness of conservative treatment. There were no different findings of noise, number of remaining teeth, and X-ray between patients and controls.

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