In attempt to assess the potential application of magnetic resonance for diagnostic imaging modality of the temporomandibular joint (TMJ), magnetic resonance imaging (MRI) of the joint was compared with the conventional radiographic images, plain tomography or computed tomography, and the actual structural features of TMJ in human cadaver were examined in relation to MR images. In addition, the effects of the cadaver treatment with formaldehyde on MRI were investigated expereimentally using the muscle and bone of the rats.
Findings obtained were as follows;
1. Magnetic resonance provided definite images of both osseous and soft-tissue components, i.e. muscle, fat and blood-vessel, without radiation exposure. The meniscus of TMJ could be also optimally visualized on MRI.
2. At present, however, it could not obtained precisely the detailed information of the meniscus on MRI, due to less sensitivity for detecting the pathological changes within the meniscus.
3. Magnetic resonance needed to put a restraint on a patient for long time to generate images and so its availability was limited in respect to patient tolerance.
4. MR images of the rat were markedly influenced by the treatment with formaldehyde and then it was desirable to obtain the precise phantom for the compensation.
5. Together with the development of technology, the improvement of image definition and the reduction of exposure time of MRI might be expected. Subsequently the excellent imaging modality as an aid to diagnostic procedure of TMJ might be developed for the future. On the other hand, it was suggested that the standardized system of MRI shoule be established.

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68 joints associated with disk displacement with reduction were examinated whether they were candidate for anterior repositioning splint (AR-splint) therapy. 53 joints were evaluated as to be candidate and treated with AR-splint. Another 15 joints were evaluated to be not candidate and had charactaristic configulation of disk (biplanar), style and timming of sound (crepitus, early at closing). Differences of the configulation of disk and the style and timming of clicking were found between the group of candidate and not to be candidate. We analysed the effectivenes of AR-splint in 53 joints according to whether click recurred or not when the splint was removed after 8 weeks and mandible was returned to original position. 43 joint (81.1%) were again experienced clicking and in only 9 joints (17.0%) the disks were kept recaptured and clicking was not experienced at any time. The clicking period of non-recurrence group was shorter than that of recurrence group (p<0.05).
No statistically significant differences were found between two groups about a configulation of disk and a style and timming of clicking.
As previous rports showed, temporomandibular joints with clicking can be succesfully treated by anterior repositioning splint. This study showed recurrence of clicking in majority of patients when the splint was removed after 8 week.
It suggested that more permanent devices are needed to stabilize the mandible in an anterior position and maintain the recaptured disk in a normal relationship to the condyle.

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The purpose of this study is to clarify the correlation with disk deformity to therapeutic effect in internal derangement with closed lock of the temporomandibular joint (TMJ). The subjects were 96 joints in 89 patients, which morphologically devided into three types of disk configuration by means of double spacing arthrotomography, the first type-prolonged disk (39 joints), second type-folded disk (11 joints), and third type-massed disk (46 joints). The treatment modalities and each success rate were mandibular manipulation technique (49.0%), pumping manipulation (29.5%), anterior repositioning splint therapy (0%), arthroscopic lysis and lavage technique (80%), and open arthrotomy of the TMJ (90.9%).
The total therapeutic success rate was 90.0%, consisted of first type with 97.4%, second type with 72.3%, and third type with 87.0%. In manipulation and pumping manipulation technique, success rates of the third type were statistically smaller (34.8%, 16%) than the rares of the first type (64.1%, 50%) and first type+second type (62%, 33.3%). These results indicate that the joint with massed disk is thought to be the most advanced disease, and is indicated for surgical therapy in selected cases.

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The purpose of this study is to clarify the differential diagnosis of TMJ dysfunction by analyzing signal characteristics of TMJ sounds. These sounds were recorded using two small accelerometers fixed on the skin of zygomatic arches of the patients who had TMJ dysfunction. The power spectra, the band width and the energy (squared integral) of the each signal were calculated using signal processing method by the FFT (Fast Fourier Transform) analyzer. Based on the comparison between the audible and non-audible TMJ sounds on the graphs, it was found that they had unique distribution with clear separated clusters. The following conclusions were obtained; 1) the most accurate signals were recorded from the zygomatic arches. 2) It is possible to classify audible and non-audible TMJ sounds using the signal processing method. 3) the changes of jaw moving velocity were concerned with characteristics of TMJ souns. 4) the silent periods were recognized in the action potentials of masticate muscles in relation to TMJ sounds. This methed can be used to understand the disordered condition of TMJ since the symptom of the patients agreed with the findings drawn from the analyzed signal characteristics.

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Morphological changes of condylar heads of 26 TMJ arthrotic patients were followed up by a selected lateral TMJ tomography. An average age of the patients, 5 males and 21 females, was 42 years and 8 months at the time of first radiologic examination. A time of interval between the first and the following examination varied widely with the patient from 2 months and a half to 4 years and 9 months with a mean value of 1 year and 5 months.
Based on the selected lateral TMJ tomograms, a mode of the bony structural changes of the condylar heads were divided into 4 radiologic groups;
(1) Twenty condylar heads (38.5%) with normal shape on initial radiograms showed no remarkable structural changes among examinations.
(2) The structural changes occured on 2 condylar heads (3.8%) which indicated no significant abnormal radiographic appearance at the first examination.
(3) Substantial structural abnormalities were found on the 30 condylar heads at the first examination. Thirteen of them (25.0%) showed little changes during the follow-up period.
(4) On the remained 17 condylar heads (32.7%) with substantial structural abnormalities, more extensive morphological changes of condylar heads were revealed by the follow-up lateral tomography.
Eventually, of the 52 condylar heads, 19 evidently showed different radiographic image among the first radiologic examination and follw-up.
The periodic radiologic follow-up is indispensable for the TMJ arthrotic patients in the current stage of a research for TMJ. Because, if radiograms reveal the bony structural changes at the first visit of a patient, whether they will be in a reparative stage or in a destructive stage is difficult to be evaluated.

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We have recentry devised a new arthroscopic suturing technique and have put this procedure to clinical use. The procedure uses a newly developed suturing needle suitable for use under arthroscopy. The needle is inserted into the articular space from the anterior epidermis of the temporomandibular joint and suturing is performed under arthroscopy. Then the needle is brought out into the anterior wall of the external auditory canal by way of the posterior wall of the articular space where the needle is threaded. The needle is again brought back into the articular space to anchor the intraarticular structures onto the posterior wall of the articular space by so-called circumferential ligation.
This technique is suitable for use in the treatment of patients with habitual dislocation, hypermobility, or anterior disc displacement of the temporomandibular joint. The procedure is apparently useful, as we have obtained good clinical results with this tecnique in combination with Nd-YAG laser.

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The modified shaped (table shaped) Pivoting splint was used to treat for internal derangement of the temporomandibular joint.
We applied to this splint for the following purpose.
1) The unlocking to cases of the closed locking.
2) The prevention for the reccurence on the patients that unlocked by the mandibular manipulation technique.
3) The prevention for the reccurence on the patients that unlocked by the mandbular manipulation technique with the pumping into upper joint space of the TMJ.
4) The improvement of the displaced disk on the cases of late opening clicking of the TMJ.
This splint was adapted on 98 cases of the Internal derangement of the TMJ.
The treatment results wers as following.
1) In 23 cases of unilateral closed locking, the unlocking was obtainted in 6 cases (26%).
2) 35 cases of unlocked by means of the manipulation technique were applied for the pivoting splint in purpose of prevention of the reccurence. In 16 cases (46%), the reccurences was not appeaed.
3) In 23 cases of remaining unlocked by the means of pumping manipulation, 19 cases (82%) showed no reccurence.
4) In 9 (53%) among 17 cases of late opening clicking, the late opening clickings changed to the early or intermediate opening clickings.

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The clinical evaluation of 559 patients with temporomandibular joint disorders, who visited our clinic from January 1979 to December 1988, was made. Mean percentage of these patients during past ten years was 5.8%, and they tend to visit our clinic increasingly year by year. The patients consisted of 152 males and 407 females, and the ratio of male to female was about 1:2.7. Distribution of age groups had two peaks in twenties and fifties. 34.0% of the patients complained of both temporomandibular joint and difficulty in mouth opening at the first vesit. 86.4% of the patients experienced temporomandibular joint pain, 56.7% difficulty in mouth opening, and 45.1% temporomandibular joint noise, respectively. Frequencies of the individual types according to the proposal classification of Japanese society for temporomandibular joint disorders (1986), were 24.7% for Type I, 18.4% for Type II, 47.6% for Type III, 7.8% for Type IV and 1.5% for Type V, respectively. Treatments consisted of dental splints (53.3%), medication (34.7%), training of mandibular movement, tooth extraction, orthodontic therapy and others. One of these treatments was applied in 42.9% of the cases, two treatments in 37.6% and three or more treatments in 14.5%, respectively. Complete recover was observed in 34.0% of the patients, unchanged symptoms were in 3.9% and discontinuance of the treatment in 62.1%, Questionnaires were sent to 486 patients, who have been treated from 1979 to 1987, and 39.9% of patients replied. Among ther, 41.8% of the patients was considered to be cured.

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In this study, the correlation between TMJ arthrosis and psychological factors was discussed. 91 patients with TMJ arthrosis visited our clinic from July, 1987 to March, 1989 were observed. The studies were performed on 63 patients who agreed to the tests (Y-G, MAS, CMI).
A correlation between the type of TMJ arthrosis and the results of the tests was investigated. Most of type I TMJ arthrosis group indicated Director type and Calm type, and type II or type III TMJ arthrosis group belonged to Director type, and type IV TMJ arthrosis group was connected with Calm type and Average type in Y-G. Then, type IV TMJ arthrosis group classified in I and II in MAS. Type I TMJ arthrosis group and type II or type III TMJ arthrosis group showed in categories I and II, type IV TMJ arthrosis showed in categories III and IV in CMI.
A correlation between the type of TMJ arthrosis and the results of the tests was revealed. It was suggested that the patients with type IV TMJ arthrosis had many psychological factors.

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The etiology of temporomandibular joint (TMJ) dysfunction remains unclear in spite of recent progress in several diagnostic methods. In order to obtain more information of this disease, we performed this study.
Patients of TMJ dysfunction who visited our clinic from 1981 to 1988 amounted to 1408, occupying from 9 to 10% of all outpatients in the last 3 years. The 1408 cases from 1981 to 1988 were analyzed regarding their age and sex, and 108 cases of first half of the year in 1988 were analyzed more extensively by use of the classification which the 7th TMJ workshop (Gakukansetu-kenkyukai 1987) proposed.
We have found several findings as follows.
1) The sex ratio of TMJ dysfunction patients was 1:2.6. The incidence of TMJ dysfunction patients showed highest frequency from 15 to 19 year of age.
2) Type III of TMJ dysfunction was most frequent (61%). Typle III was further divided into III a (anterior displacement of the disk with reduction) (31%) and III c (anterior displacement of the disk without reduction) (30%). Type I was 21%, type II was 16% and type IV was 2%.
3) In males there were few patients of TMJ dysfunction type III c.
4) 77% of TMJ dysfunction patients had muscle symptoms.
5) 84% of TMJ dysfunction patients had occlusal problems, Occlusal interferances in lateral and protrusive movements were observed in every type of TMJ dysfunction, but disturbance of centric occlusion were more frequently observed in type III of TMJ dysfunction.
6) Treatment methods were evaluated for each type of TMJ dysfunction.

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According to new classification, we studied of 139 patients with temporomandibular joint arthrosis, who visited our clinic from January to December in 1987. The Type III and related types were found in 105 cases. 93 cases of these were subjected for this study. We did the clinical assessment of the conservative treatment one month later. In result, cases with early clicking type of anterior displacement with reduction showed the best improvement in sign and symptom. (the effectiveness rate 75.8%) and intermittent locking type 63.6%, late clicking type 56.3%, closded lock type 54.5%

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Ankylosis of tempolomandibular joint is a disorder which strictly limits jaw movement resulting from the fibrous or bony union of the joint surfaces.
It is generally agreed that surgery is the only effective treatment for this disabling condition and several procedures have been reported by some authors.
However it is considered that the surgical method is not still established because we frequently encountered recurrent cases and many recurrent cases are reported on some articles. Interpositional arthroplasty is considered best suited to restore the jaw function, maintain the jaw position and prevent reunion. Nevertheless, the choice of materials is very difficult in application of procedure, because so many materials have been introduced so far.
In our department, intepositional arthroplasty with a vitallium temporal fossa which is fixed firmly to temporal bone with screws have been carried out in five cases of temporomandibular joint ankylosis. This technique is believed to produce satisfactory results, since a vitallium plate maintains its stability in vivo nd is fixed to an immobile portion which makes it possible for the plate to stay in position for long time.
This article is a clinical report of our treatment experiences. Satisfactory function was restored in all five cases, and the post-operative follwup confirmed the satisfactory function was maintained for four to eleven years. In these patients, the maximum jaw opening was at the region of the central incisor after surgery showed an average of 30.2mm which were limited within 9.4mm at mean level before operation. During the period of evaluation, there was neither deviation of vitallium fossa nor bone resorption of mandibular condyle and local inflammatory reaction.

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A single blind study was performed to evaluate the effectivess of He-Ne COLD LASER on TMJ Arthrosis. Thirty-three patients (8 men and 25 women) were given the laser treatments every second day for ten days. To estimate placebo effects, eight patients were treated using the device which did not radiate the laser. Results had shown that 25% of the patients with underwent placebo treatment responded. For the patients which were given laser treatments, 72% of the patients responded. When subjected to chi-square testing, the difference between them was significant (P<.025). It was also effective in treating patients with trismic condition. It is suspected that improvement of trismic condition was achieved when pain was also removed. Disappearance of TMJ sounds occurred in some patients but the rationale behind this is unknown. It was found that the effectiveness of laser radiation was usually achieved within 10 exposures. No side effect and complication were observed in all of cases.
These results showed that the use of COLD LASER is beneficial for TMJ Arthrosis patients.

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Abnormal development of the condyle can often be atributed to injury or infection during the growth period. Unilateral hypoplasia of the condyle often results in asymmetry of the face and causes limitation of joint movement.
A 23-years-old woman was reffered for evaluation of asymmetry of the mandible. She noticed this at 15 years old. She was in good health and there was no history of trauma or infection in the TMJ area except a contusion on her head at 14 years old.
Her face was noted to be asymmetrical with the chin deviating on the right. The asymmetry was more evident when the mouth was opened. Radiologic examination showed mandibular deformity with hypoplastic condyle of the right TMJ.
Other examination failed to prove the relationship with craniomandibular syndrome. The surgical correction was performed under general anesthesia consisting of as follow:
1) Osteotomy of the mandibular angle on right side
2) Genioplasty
3) Application of hydroxyapatite block for the mandible on the left side
Facial asymmetry was improved, she is now under observation.

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