The purpose of this study was to find the course and the reason why patients with closed lock without osteoarthritis did not continue treatment.
In our clinical research about primary treatments for patients with closed lock without osteoarthritis, 19 out of 89 patients did not come back during a three month period of the treatment. A questionnaire about the TMJ symptoms at the time of three months after the initial treatment was mailed to all 89 patients. The 19 dropout patients were compared with the remaining 70 patients who were regularly followed up after the initial treatment.
The improvement rate in the dropout patients (73.3%) was significantly higher than that in the followed-up patients (42.9%). The major reason was the improvement of TMJ symptoms.
Dropout TMD patients showed a higher improvement rate of TMJ symptoms, and this is a major reason why they did not visit our clinic for further treatment.

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The purpose of this study was to investigate the relationships between the temporomandibular joint (TMJ) mobility and the habitual chewing side or the symptomatic side of temporomandibular disorders (TMD).
Fifty patients from whom informed consent was obtained participated in this study (12-35y: mean 24y). They were asked about their habitual chewing sides and TMD symptomatic sides. TMJ mobility was evaluated based on the amount of the nonworking side condylar translation recorded by computer axiograph (CADIAX) during bilateral movement. They were also asked which side of the mandible was easier side to move. Moreover, the TMJ mobility under 5mm was defined as hypomobility, over 12mm as hypermobility, and the remainders were regarded as normal mobility. Based on the above criteria, the mobilities of 100 TMJs of 50 subjects were evaluated. The test for the proportion and the chi-square test for independence was carried out for statistical analysis.
No significant relationship could be found between the habitual chewing side and the TMJ mobility evaluated based on condylar translation. Among 50 subjects, 29 could move their mandible easier to their habitual chewing side and 15 to the opposite side to their habitual chewing side, and this difference was statistically significant. Among 100 TMJs, on the other hand, 2 were judged to have hypemobile joints, 23 hypermobile, and the remaining 75 were regarded to have normal mobility. On the other hand, 16 of 23 (70%) hypermobile TMJs were symptomatic, which was a significantly higher rate than that observed in TMJs of normal mobility (43%).
It was inferred that there is a significant tendency that the habitual chewing side could coincide with the easily movable side, and the possibility was suggested that the hypermobile TMJ could become TMD symptomatic.

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Pain in TMD patients can be caused by morphoragic, psychologic, and neurogenic factors. Therefore, when TMD is evaluatea, a unitary viewpoint is inappropriate and plural one is necessary. In this study, pain in 80 patients with internal derangement of TMJ was evaluated by not only conventional method of VAS as a unitary one but also JMPQ (Japanese McGill Pain Questionnaire) as a plural one, and the results of the two methods were compared. The results were as follows.
1) Forty-one percent of patients chose one or more words in one category as the expression of their pain and 53% of them several words at least in two categories, though JMPQ comprises four categories.
2) Patients who chose words in the sensory category indicated a tendency to express their pain in higher value of VAS than those who didnot.
3) Patients who felt TMJ-pain on pressing showed higher value of VAS on chewing than those who didnot.
4) No words in four categories of JMPQ corresponded to high value of VAS regarding difficulty to sleep.
5) Patients who suffered TMJ-pain exhibited higher value of VAS regarding pain when doing nothing special, and those who suffered muscular pain on chewing lower value of VAS regarding a problem in daily life.
6) There are probably some sorts of pain that cannot be expressed by the VAS.

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Although the palpating procedure is convenient to evaluate pain status at the muscle site and TMJ, the results are not necessarily objective. By means of utilizing a small thin force sensing film attached to the finger tip, quantitative measurement was enabled during palpation. This study was composed of 2 experiments. The first experiment, involving 20 dentists, was conducted to understand the relationship between pressure pain threshold (PPT) and pressure increment rate (PIR) during palpation. PPT was associated to PIR when utilizing a plunger pressure device (r=0.82). However, there was little correlation between the PPT and PIR on palpation (r=0.33). This specific PPT-PIR relation might be caused by the difference in force direction between the palpation and the plunger device. In the second experiment, 22 dental students were tested. They were given instructions to apply 1.0kgf to the mid-point of masseter region of the test subject. With the aid of actual pressure feedback training, the mean values of finger pressing force before training, right after the training, and 1 week following the training were an average of 0.64, 1.25, and 1.58kgf, respectively. Since the difference between the target and actual value was reduced in the post training measurement, the developed 2-channel pressure measuring system was found to help regulate constant force during palpation and could be expected to be a useful educational tool for palpation.

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In this study, Gd DTPA-BMA (gadolinium diethylene triamine pentaacetic acid-bis methyl amide) was used as a contrast medium for magnetic resonance imaging in patients with temporomandibular joint disorder. This contrast medium is considered to cause less adverse reaction than Gd-DTPA. In all cases, no adverse reaction to Gd DTPA-BMA was noted during and after contrast imaging.
Magnetic resonance imaging was performed before and after intravenous administration of Gd DTPA-BMA to obtain sagittal section of 46 joints in 23 patients with temporomandibular disorder. The mean age of these 23 patients, consisting of 18 females and 5 males, was 39.4 years.
Visual evaluation revealed markedly higher contrast effects with the use of Gd DTPA-BMA during both opening and closing of the mouth. When comparing the difference in the intensities, MRI enhancement was significantly higher during opening. It was also found that SIR was significantly higher during opening than during closing in all joints, but there were no significant differences between different groups with different symptoms. There were also no significant differences in the location of the disc.

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Pathogenesis of the internal derangement or degenerative arthrosis of the temporomandibular joint (TMJ) is considered to be due to the TMJ loading condition. This report deals with the biomechanical method using pressure sensitive film (Prescale TM) to estimate TMJ loading which varies with jaw dimension, occlusion, muscular insertion, and chewing force of differnt individuals.
During biting, muscle force is in equilibrium with occlusal force and TMJ loading, where three eqilibrium equations can be given by considering the force balance in the direction vertical to the occlusal plane -(1), and the balance of moment around the axis passing the bilateral condylar heads -(2) and around the axis of the median line parallel to the occlusal plane. Since muscle force is assumed to be proportional to its time-integrated electromyogram (i-EMG) in the isometric contraction and the maximum muscle force is to be proportional to its cross section, the terms containing muscle force in the above equations can be replaced by the i-EMG readings multiplied by a constant ratio. By giving real EMG readings, moment of the occlusal points computed from Prescale recordings and anatomical data from the cephalogram, solving the equation (2) can determine the ratios which are constant for the muscle type. Muscle force by multiplying i-EMG heights by the obtained ratio, force and moment of the occlusal contact points recorded on a Prescale sheet and anatomical data further afford to give the value of TMJ loading of different biting at the centric occlusion by solving the simultaneous equations consisting of (1) and (3).
Estimation of TMJ loading in this report has also shown that the TMJ bears more loading on the side where greater muscle force is exerted.

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Cycloxygenase (COX) is a key enzyme in the generation of prostaglandins. There are two isoforms of COX that share the same enzymatic activity but differ markedly in their regulation. COX 1 is constitutively expressed in many tissues whereas COX 2 is considered an inducible isoform transcribed primarily during inflammatory reactions. In this syudy, the expression of COX 1 and COX 2 in 16 human temporomandibular joint (TMJ) samples with internal derangement of TMJ and in 10 control specimens was investigated by an immunohistological technique using paraffin-embedded tissue and specific anti-human COX 1 and COX 2 polyclonal antibody. In the control specimens, COX 1 and 2 were observed on the fibroblast-like cells and endothelial cells. As in the internal derangement of TMJ cases, COX 1 and 2 were observed frequently on the fibroblast-like cells and endothelial cells. However, COX 1 and 2 expression in internal derangement of TMJ samples was more intensive than in control cases. Furthermore, in the hypertrophic synovial membrane, specific COX 2 expression was detected on the synovial cells in the internal derangement of TMJ cases. The presence of COX 2 might be an important mechanism regulating inflammation in the synovial membrane with internal derangement of TMJ.

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The purpose of this study was to evaluate the efficacy and safety of arthroscopic synovectomy in rheumatoid arthritis of the temporomandibular joint (TMJ) utilizing Holmium: YAG laser irradiation, which is a minimally invasive surgical procedure.
The patient was a 24-year-old female who had rheumatism and complained of pain upon mouth opening. X-ray findings showed the surface erosion of the mandibular head. MRI findings showed joint effusion and anterior displacement of the disc without reduction. The patient had been treated nonsurgically prior to arthroscopic surgery without success.
Holmium: YAG laser irradiation was used for synovectomy. Total energy was 8.78kJ. The patient had less pain and greater jaw mobility after operation. Surgical complication wasn't encountered.
Holmium: YAG laser irradiation in rheumatoid arthritis of the TMJ was considered to be a safe, effective procedure of arthroscopic synovectomy.

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Eight cases with chronic mandibular dislocation, which showed at our clinic from April, 1985 to March, 1995, were studied clinically. The average age of patients were 60.9 year-old (ranged 48 to 72 year-old), the rate of man: woman was 1: 3. Two cases of psychic disease, 2 cases of cerebral infarction, 2 cases of digestive organ disease and 1 case of breast cancer were included. Etiology of dislocation were intubation of anesthetic procedure among 4 cases of all. Averaged periods of dislocation was 6.4 months ranged 2 months to 2 years. All patients were treated by minimum invasive procedure including manual reduction alone under general anesthesia (2 cases), manual reduction with bone hook (4 cases), intermaxillar traction combined mobilization of mandibular condyle by manipulation and elastic and arch bar (2 cases). All cases were indicated mandibular rehabilitation after 2 weeks of limitation of mouth opening, and succeed in reduction without open surgery of TMJ. Postoperative course (follow up periods ranged 6 mouths to 2 years, averaged 1.1 years) was good except 1 case, which occurred redislocation after 10 months of success reduction using bone hook. Postoperative X-ray findings showed severe articular changes in 2 cases of intermaxillary traction, but there was no problem clinically.

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The purpose of this study was to explain how limited cone beam X-ray CT (Ortho-CT) is useful for the diagnosis of temporomandibular joint (TMJ) disorders. It uses a 4-inch image intensifier and small conical beam with an exposure field of 3.0cm in height and 3.8cm in diameter. Images in three sectional planes can be reconstructed from the data of one exposure in approximately ten minutes. Each voxel is an orthocubic figure whose sides are 0.136mm, and the imaging area consists of 240, 280, and 280 voxels respectively. Since the exposure field is small, the dose is very low compared with ordinary CT examination. The Ortho-CT and X-ray tomography were used in this study. The subjects were TMJ disorder patients. X-rays of 26 joints of 13 TMJ disorder patients were token to compare Ortho-CT with hypocycloidal tomography for the assessment of osseous structures of TMJ. Taking both mandibular condyle and articular eminence with one Ortho-CT is better than hypocycloidal tomography for observation of osseous structures. In conclusion, the results of this study suggested that Ortho-CT images are an excellent means for diagnosis of bone change of TMJ disorders.

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A case of habitual temporomandibular dislocation treated with T-shaped miniplate eminoplasty and its evaluation of the mandibule were reported. A 51-year-old male suffering from mental reterdation vis tited our hospital with the chief complaint of difficulty in mouth-closing. After clinical diagnosis of habitual temporomandibular dislocation, procedures of eminoplasty using a T-shaped miniplate was done under general anesthesia. Postoperative course for 10 months was uneventful, and no relapse was observed. The evaluation of mandibular movement was performed by Sirognathography and its analyzing system. Result of this analysis indicated that upon mastication, open-close movement of the mouth was improved, being smoother, and stable centric occlusion was obtained. These results indicate that the prognosis of this method is satisfactory and function of mandibuler movement can be maintained within the normal range.

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This study was performed to investigate the correlation between the mandibular condyle form in TMD type IV (osteoarthrosis) patients which could vary with the passage of time and the clinical course. Morphological bone changes of the mandibilar condyle were examined by MRI before, during, or after treatment. Follow-up examination was performed 6 months or after the first examination. TMJ pain and maximal mouth opening (MMO) were also examined. The results were as follows:
1) Among the 18 TMJs, which showed erosion on the first examination, 15 TMJs (83.4%) varied to other forms at the follow-up examination (flattening included normal form; 12 TMJs, concavity; 1 TMJs, osteophyte; 1 TMJs, deformity; 1 TMJs).
2) Of the 18 TMJs which showed erosion on the first examination, 17 TMJs (94.4%) had TMJ pain. Of the 15 TMJs, in which erosion altered to other forms at the follow-up examination, 13 TMJs (86.7%) had no TMJ pain at the follow-up examination.
3) Of the 18 TMJs, which showed osteophyte onthe first examination, 8 TMJs (44.4%) had TMJ pain at the first examination. Of the 15 TMJs, which remained osteophytic at the follow-up examination, 3 TMJs (20%) had TMJ pain at the follow-up examination.
4) In the patients who had erosion in the unilateral condyle at the first examination, and erosion altered to other forms, maximum mouth opening increased highly at the follow-up examination (first examination: 33.3±6.9mm, follow-up examination: 44.2±5.4mm).

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The arthrography is beneficial to diagnose temporomandibular joint disorder, especially prior to determination of interarticular condition. Usually, double contrast arthrography CT images using multiplanar reconstruction (MPR) picture is performed, and good findings are obtained. However, arthrography requires contrast media, which could result in side effect. Frequently, the side effect of contrast media is observed after intravenous administration and arthrography is rare. Until now, the arthrography has been safer than intravenous administration, concerning side effect of contrast media. However, there have been a case of side effect, which was suspected to be caused by contrast media. This case was erythema in the injection area and the front of the neck. The case required recovery administration of steroid. Thus whether the side effect due to arthrography can occur was investigated. As a result, this symptom was similar to intravenous administration. In consideration of its mechanism of development, it was assumed that an allergy was caused by antigen with contrast media. Thus the side effect occurred due to temporomandibular joint arthrography, and it was decided that the same symptoms were caused by contrast media. It was considered that when performing temporomandibular joint arthrography using contrast media, the same to attention must be paid when perfoming other contrast radiography.

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The effect of conservative treatment for types II, III, and IV temporomandibular joint dysfunction (TMJD) were evaluated in 613 patients during the last 5 years. Of these, thirty-seven patients who became free from TMJD within 2 months after the start of treatment (CR group) and eighteen patients whose TMJD was not improved even after 3 months (NI group) participated in the present study. The findings of magnetic resonance imaging (MRI) and symptoms before treatment and the response to treatment in both groups were comparativeily evaluated, and the prognosis-predicting factors were identified as follows: 1) The patients in the NI group were older than those in the CR group (51.2±12.5 years old vs. 34.4±17.9 years old). 2) The history of TMJD in the NI group (6.9±6.0 months) was longer than that in the CR group (2.3±3.0 months). 3) Crepitus was observed more often in the NI group than in the CR group. 4) The incidence of irreversible anterior displacement of the articular disc in the NI group (83.3%) was higher than that in the CR group (16.2%). 5) The articular discs in the NI group were more anteriorly displaced than those in the CR group. 6) TMJD was classified as type IV in 14 of 18 NI group patients, while in the CR group type IV was not observed. In conclusin, the response to conservative treatments is correlated with patient's age, duration of the dysfunction, presence of crepitus, and severity of the articular disc displacement. Therefore, to avoid time-loss by noneffective conservative treatment, the evaluation of these facters is recommended before the start of TMJD therapy.

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Although the relationship between osteoarthritis of temporomandibular joint and craniofacial morphology has recently been reported, clinical correspondence may be late because of the variety of clinical features in osteoarthritis. The present study was performed to investigate the clinical guidelines for osteoarthritis in patients with jaw deformity, from the relationship between the TMJ pathology and tapping movement which is clinically used as occlusal criterion. Experimental data was obtained from forty-eight patients with jaw deformity (mean age: 20.5 years) using helical computed tomography, magnetic resonance image and a system for recording tapping movements with 6 degrees of freedom.
Deformity and erosion were frequently seen in subjects with bilateral condylar bony change group (bilateral group) and deformity was the common feature in subjects with unilateral condylar bony change group (unilateral group). Anterior disk displacement without reduction (ADNR) was the most common feature in the unilateral and bilateral groups.
By comparing the types of condylar bony change, the incisal and condylar points in the bilateral group were significantly more unstable during tapping than the group without condylar bony change. By comparing the types of disk displacement, the incisal point during tapping was more unstable in subjects with bilateral ADNR or ADNR and anterior disk displacement with reduction (ADWR), and the condylar point during tapping was more unstable in joints with ADNR and ADWR displacing condylar bony changes than joints with normal disk position. No difference of incisal and condylar points was found when anteroposterior craniofacial morphology was used as the criterion of comparison.
It was suggested that instability of incisal and condylar points during tapping might be related to the pathology of the temporomandibular joint in orthognathic patients.

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