In recent years, TMJ dysfunction is reported to be increasing, but at present its etiolgy is not clear now. We have been studying the chewing movements, which are the most important functional mandibular movements. The possibility is indicated that the interference at the non-working side of lateral movement have a harmful effect on the functional occlusion system. In this study, the effect of the interference at the non-working side on chewing movements was investigated.
30 people were selected as the interference group with the interference at the non-working side of lateral movement, and 10 people without that interference as the control group. The interfernce group was divided into two groups, interference normal group without TMJ dysfunction and interference abnormal group with TMJ dysfunction. Jaw movements were recorded and analysed by Sirognathograph Analysing System II.
The results were as follows;
Some characteristic patterns in the frontal plane were observed in the chewing mevents of the interference group.
1. On intereference side chewing, a concave opening pattern was significantly observed. Especially of the interferance abnormal group, the working side deviate reverse crossover opening pattern was significantly observed.
2. On non-interference side chewing, a closing path with a step or a concave part was significantly observed.

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Patients with TMJ dysfunction often suffer from TMJ noise. However, determining the side at which the noise occurs is not always easy in auscultation or when picking up the noise electrically, because the sound is carried across the bony structure and picked up on both sides.
To solve this problem, we utilized a three-directional accelerometer, measuring the sound on both sides in the hope that a difference in measurements would identify the side of the noise.
We discovered that time difference between the acceleration peaks for the side originating the sound was shorter than that of the other side.
Our report also contains a few observations on the result of this study on patients with plural TMJ noises occurring during one movement of the mandible.

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The mini-splint was applied to 21 patients with internal derangement of the temporomandibular joint (TMJ) who had failed in treatment by the manipulation technique. This appliance was constructed of two splints, which were built on the bilateral upper first bicuspids (teeth number 14 & 24, FDI) by methyl-meta-acrylate. As a result, the mean of the maximum interincisal distance was improved from 25.0mm before to 41.0mm after splint therapy. Among 21 patients, 18 patients were improved in interincisal opening, 12 patients were free from TMJ pain, and 3 patients were relieved from joint noise.
Our studies indicate that this technique is useful as one of the treatment methods of TMJ internal derangement.

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The fibrous connection of the discal attachmen to the condyle and to the other structures around the disk was investigated histologically in order to reconfirm what Rees calls the bilaminar zone.
Eleven TMJs were taken from fresh cadavers. Sections, obtained from six materials with condyle protruded, were observed. The Results were as follows:
Most of the collagen fibers composing the articular disk attached to the area from the medial and lateral pole to the corner region of the posterior aspect of the condyle. But these fibers were not recognized on the posterior aspect of the condyle.
A few of the fiber bundles composing the supra-lateral part of the disk were linked with the fibers of the periosteum of the lateral end of the articular tubercle.
The fibers of the superficial layer of the posterior band linked with the fibers beneath the synovial membrane of the retrodiscal area, but these fibers were not observed to connect the disk with the posterior wall of the fossa.
At the medial end of the disk, the elastin rich fibers originating from the petrotympanic fissure attached to the disk. There were no other fibrous structures directly connecting the disk with the posterior wall of the fossa.

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The fibrous structure of the retrodiscal connective tissue was investigated histologically in order to reconfirm what Rees calls the bilaminar zone,
Eleven TMJs were taken from the fresh cadavers. The sections, obtained from six materials with condyle protruded, were observed mainly.
The Results were as follows:
The retrodiscal area was composed of the collagen fibers originating into this area from the petrotympanic fissure, from the conjunctive area of the posterior wall of the fossa with the lateral wall of the articular cavioy, and from the conjunctive area of the posterior slope of the aricular tubercle with the lateral wall of the articular cavity. In the superficial layer of the retrodiscal area, these fibers crossed each other, and a few fibers jointed with these fibers from the superficial layer of the disk and from the posterior wall of the articular fossa. The arrangement of these fibers had various directions, however most of fibers tended to run medio-lateraly.
The fiber bundles containing many elatic fibers ran into the retrodiscal area from the petrotympanic fissure. Although these fibers connected the most medial side of the disk with the medial side of the posterior wall of the articular fossa, they had many branches composing the retrodiscal area as staed above. The fibers were very wavy, in spite of the protruded position of the disk. So these fibers were not considered to have a role in pulling back the disk in the retruded phase of the mouth closing.
New findings as to the retrodiscal connective tissue were obtaine in this research. They were different from Rees's description.

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Clinical retrospective investigation was conducted on mandibular condylar fractures of 100 hospitalized cases at the Department of Oral Surgery, Kyoto University Hospital durgng the period from 1973 to 1983. The following results were obtained,
1. There were 74 males and 26 females. The age of the patients at the time of injury ranged from 4 to 78 years old. The average age was 28.1 years old.
2. Twenty-six patients were treated within a week of injury, 22 cases within 2-weeks and 33 cases were treated afler more tham 3 weeks.
3. Of the 100 cases, 70 were unilateral fractures and 30 were bilateral. The incidence of the concomitant fractures of the mandible were higher in bilateral than in unilateral condylar fractures.
4. On fracture level and formn 130-site in 100 patients were divided according to the classification of Maclennan and Kubo. Dislocated and high condylar fractures were most frquently observed.
5. Surgical reduction was mainly achieved in low neck fracture, and the contrary conservative treatment was observed in the higher level fracture. On the other hand condylectomy was infrequently indicated in the dislocated head fracture.

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Sixty-six joints in 49 patients with mandibular condylar fracture were investigated by means of long-term follow-up observation. The group of patients consisted of 39 males and 10 females with ages from 15 to 75 years. The classification of the fractures was follows: MacLennan type 1; four, type 2; four, type 3; 39, and type 4; 39 joints respectively. Treatment was as follows: 25 joints were by conservative therapy, 31 joints were by surgical fixation, and 10 joints condylectomy. The followup period of observation ranged from 18 months to 10 years and one month an average of five years and seven months. Clinical assessment was based upon Nakatomi's dysfunction. index on mandibular condylar fracture, of which the criteria are as follows; Excellent (No clinical dysfunction sign on the TMJ), Fair (Slight pain, noise, and limited range of motion of the mandible, but clinically no affected mastication), Poor (Moderate dysfunctioned jaw), and Failure (Severe dysfunctioned jaw).
23 joints in 18 patients were ranked as having excellent results. 31 joints in 22 patients were assessed as fair. Ten joints in seven patients were defined as poor, and the remaining two joints in two patients were failures. The overall success rate was 81.7%. There are no statistical differences between patient's groups based on age, sex, uni-/bilateral modality, with/without other concomitant fracture, surgical/conservative procedure, location and form of fractures, and duration of period from injury. These results indicated that the conservative procedure would be the first choice as a reasonable and less invasive procedure for functional repair of mandibular condylar fracture. On the other hand, as most patients had some dysfunction sign on the TMJ after mandibular condylar fracture, a more appropriate treatment, surgical or otherwise, should be found.

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A case of complete rupture of the right TMJ disc was described.
A 43 year old woman visited our hospital with the chief complaint of a mild pain in the right TMJ. Initially, a conservative treatment using the occlusal splint (condylar repositioning appliance) was carried out. This was because she had reciprocal clicking of the right TMJ which had occured not long before and it seemed that the symptoms were due to the trouble with the disc.
In spite of this treatment, for 6 months no improvement was obtained and the reciprocal clicking changed into crepitation. Moreover the double contrast arthrotomographic image indicated a perforation or a wide rupture of the disc, and deformities of the articular bone. Then a right TMJ osteoarthrosis with wide (complete) disc rupture was diagnosed, and a discectomy was performed. The symptoms were greatly reduced by this treatment.
It was conceivable that the steroid which she had used for a long time to treat bronchial asthma caused a remarkable inhibition of the tissue repairing, and an internal derangement of the TMJ rapidlly progressed to osteoarthrosis.

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Two cases of temporomandibular arthrosis were reported.
Case 1 was a 6 years 4 months old female with pain in her left mandibular region in moving her jaw. Opening of the mouth by herself was slightly limited. Clicking noise was seen and felt from both of her temporomandibular joints. She was in the dental developmental stage II A by Hellman, and had deep overbite (5mm). Roentogenographic examination revealed a bony defect on her left condylar head. Treatment was performed with an activator. Pain was not felt and the mandibular opening recovered after 2 weeks of treatment. Roentogenographs showed no bony defect on her left condylar head after 5 months of treatment.
Case 2 was a 3 years 2 months old male with clicking noise from both of his temporomandibular joints. There was no pain and no limitation of his mouth opening. He was in the dental developmental stage II A by Helllman, and had large overjet (8mm). He has thumb sucking habit since the age of one year. He is now under regular observation.

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This clinical report presents orthodontic applications of double contrast arthrotomography and arthroscopy of the temporomandibular joint. We examined a case of mandibular shift with stomatognathic dysfunction using these techniques, and found medial displacement of the articular disk.
Generally, displacement of the articular disk is examined only from sagittal section. However, this case in dicates that frontal section of double contrast arthrotomography is necessary for the three dimensional understanding of the TMJ.
Mandibular position with disk reduction was obtained by double contrast arthrogram, and medial displacement of the disk and malocclusion were treated by dynamic positioner. It is suggested that orthodontic treatment is an effective method both for treatment of internal derangement of the TMJ and also for the final reconstruction of occlusion.

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Classification of disk configuration for 96 joints (89 patients) of internal derangement with closed lock of the temporomandibular joint was performed by means of double-spacing contrast arthrotomography. The results of the classification were presented in the first report of this series. The disk shape was divided into 3 types; the first type-prolonged shape maintaining the main parts of the disk, the second type-folded disk, and the third type-massed disk. In this article, the authors tried to clarify the correlation of disk configuration with the duration of illness and with the interincisal opening distance at the first presentation.
In the results, the average duration of clicking and locking was statistically longer in the joints of the third type. The interincisal opening distance was statistically smaller in the joints of the first type. These results indicate that the severity of the disk deformation is closely related to the duration of illness and to the joint function.

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