Two hundred patients with arthrosis of the TMJ were classified into type I-IV based on the criteria proposed by Japanese Society for TMJ (1987) and analysed statistically. The results were as follows.
(1) 12 cases (6%) were classified into type I, 20 (10%) into type II, 52 (26%) into type III, 116 (58%) into type IV. Tost cases were included in type IV. Lateral tomography was available for the evaluation of the deformity of the condyle. It was the most important factor for the criteria of the classification.
(2) There were 51 males and 149 females. The females were dominant. The age distribution had two peaks in the 2nd and 3rd decades and the 5th decade.
(3) The region of disorders: 88 cases in the left side, 81 cases in the right side, 31 cases in both sides. No differences were seen between the sides.
(4) The relation between the disorders and teeth observation: Crowdings and other discrepancies in frontal teeth seemed to have a special relation with type III, and type IV.
(5) The treatment term of each type: Generally, type III cases had a tendensy to have a long treatment term. When different cases were treatedin the same way, type IV cases seemed to have the longest term for success. In the cases of anterior disc displacement with reduction, the treatment term of the cases with less deformity of the condyle were shorter than that of the cases with severe deformity. In the cases of the anterior disc displacement without reduction, the treatment term of cases that were effective with manipulation technique were shorter. The treatment term of the cases treated successgully with two or three methods was long.

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We presented the results of application of intra-articular pumping into the upper joint compartment of the TMJ for four cases of high level condylar fracture of the mandible. The treatment modality was highly effective in improving of the jaw function i.e.; range of opening motion. In addifion, pain relief effect was apparent on the affected joint.

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This report describes a case of lateral pharyngeal edema following arthroscopic surgery. A 43-year-old man was seen in the department of oral and maxillofacial surgery with a complaint of mouth opening pain in the temporomandibular joint (TMJ) and limitation of opening (26mm). The results of a magnetic resonance imaging study revealed right anteriorly displaced disc without reduction, and serial tomograms revealed osteoarthritis of the right TMJ. The patient's symptoms were unchanged following 4 months of nonsurgical treatment with pumping manipulation technique for temporomandibular disorders. Arthroscopic procedures were then performed consisting of examination and lysis of adhesions. Tracheal extubation was retard de by the edema from the right soft palate uvula to the lateral pharynx following arthroscopic surgery. After 3 hours, the endotracheal tube was able to be extubated by reason of a return of upper airway symmetry.

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This study was designed to evaluate, both clinically and electromygraphically, the effect of Afloqualone, a centrally acting muscle relaxant, in patients with temporomandiblular joint arthrosis The subjects consisted of 10 patients with temporomandibular joint arthrosis with myofacial pain dysfunction.
Three tablets of Arofuto® (120mg of Afloqualone/tablet) were interally administrated per day for two weeks.
Each of the patients were examined clinically and electromyographically by the protocol for patients with temporomandibular joint arthrosis.
The results were as follows. Afloqualone was effective for 8 patients, but not for 2 patients.
The Electromyographic findings were in accordance with the clinical findings.

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From July through December in 1994, 60 patients with complaints of temporomandibular joint disorders were evaluated with 10MHz high-resolution ultrasonography.
On ultrasonography, a hypoechoic area covering the lateral portion of the head of the mandible were observed in all 120 joints of 60 patients.
Thickness of the hypoechoic area was less than 0.2cm in 33 joints, 0.2cm in 35 joints, and 0.3cm or more in 52 joints, respectively.
MRI was performed and compared with ultrasonography in 64 joints of 32 patients.
Articular disc displacement was seen on MRI in all 30 joints in which the hypoechoic area was 0.3cm or more in thickness on US, in 14 of 25 joints with that of 0.2cm, in 4 of 9 joints with that of less than 0.2cm in thickness on US, respectively.
Hyperintensity areas on T2-WI were seen on 20 of 27 joints with the hypoechoic area of 0.3cm or more, in 6 of 22 joints with that of 0.2cm, in 2 of 9 joints with that of less than 0.2cm in thickness on US, respectively.
The hypoechoic area was 0.2cm or less on US in 6 joints of 3 asymptomatic volunteers in which articular disc was in normal position on MRI.
Judging from the findings of US and MRI, it is likely that the hypoechoic area on US corresponds to the articular capsule and lateral ligament, and contains further displaced articular disc and joint space if it is 0.3cm or more in thickness.
In conclusion, 10MHz high-resolution ultrasonography is less sensitive than MRI in detecting articular disc displacement.
However, it could be advocated that articular disc displacement should be suspected if a hypoechoic area seen abutting the TMJ on US is 0.3cm or more in thickness.

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The therapeutic method of superior joint space irrigation with two needles, so called arthrocentesis, for seventeen patients complaining of severe and persistent pain localized in the TMJ region at jaw movement was clinically evaluated. Furthermore, the conditions in the posterior portion of the superior joint space were observed simultaneously using a very fine athroscope through a 18-gauge needle for arthrocentesis.
The visual analogue scale (VAS) of pain and maximum opening range (MOR) of each patient were recorded every week in order to evaluate the change of these factors between pre- and postoperation.
As for VAS, 11 patients (64.7%) sufficiently improved 2 weeks after irrigation: The success rate on pain was increased to 70.6% at one month and to 82.4% at 3 months later.
Concerning the improvement of MOR, four patients were unlocked during this procedure, and the others were still locking. The unlocked group showed more than 40mm on average of MOR immediately after irrigation which was continued. On the other hand, the average of MOR in the locking group was 30.2mm at 2 weeks later, but the average gradually increased to 34.5mm at 3 months post-operatively.
Arthroscopic view showed fibrilar degeneration (81.3%), including furrowing, ulceration, fibrillation, and crater formation of the surface of cartilage and/or articular disc, synovitis (75.0%), floating debrises (75.0%), adhesion (50.0%), and bleeding (43.8%). The relationship between these findings and prognosis of each person was suggested to be correlative.
Therefore, this method was found to be effective in a patients with painful internal derangement of TMJ.

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A 64-year-old woman with edentulous jaws was referred to our clinic, complaining of masticatory dysfunction and dysphagia over about 6 months. She was diagnosed as haring long-standing anterior luxation of the bilateral temporomandibular joint. Roentgenograms showed anterior dislocation of bilateral condyles and manual repositioning trials were not successful. Open surgery (discectomy and partial myotomy of the external pterygoind) was performed under general anesthesia to reduct the condylar head into the fossa. The operation included the modified Dautrey's method for restriction of the anterior movement of the condyle by making an obstruction composed of the reattached zygomatic arch.
Jaw movement exercises were indicated. The range of the mouth opening attained 37mm and new dentures were made which fitted very well. After 15 months postoperatively, no luxation occured. There was a body weight increase of about 10kg during this period. She regained the masticatory function and hes physical condition, became satisfactory.

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We undertook a clinical study to investigate the efficacy of mouth opening exercise for 20 patients with persistent closed lock in temporomandibular joint (mean age: 38.9 years, range: 16 to 59 years). The results were summarized as follows:
1) The mean of maximum mouth opening increased from 26.5mm to 40.2mm after treatment, and continued to improve during the follow-up period (mean 40.8mm) 2) Although all the patients had pain in TMJ or masticatory muscles before exercise, it disappeared or was alleviated after treatment in all patients, except for one who continued to have severe pain. 3) Crepitus that was noted in 7 joints before exercise disappeared after treatment in two joints, and other seven joints newly developed crepitus after treatment which did not disappear during the follow-up period. 4) Eight of 13 joints with normal configuration of the condylar head developed bony changes during the follow-up period. Most of the remaining joints with radiographic bony changes on first examination showed evolution of bony changes during the follow-up period. 5) This treatment was effective in 85% of our patients judging from the criteria for TIM meniscus surgery by American Association of Oral and Maxillofacial Surgeons (1984).
These results suggest that this treatment is effective and should be the first treatment of choice for patients with persistent closed lock.

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A microscopical study was made on the effect of the condylar hypermobility in the rat temporomandibular joint synovium. The pathological changes were mostly observed on the anterior synovium of the upper joint compartment as follows
(1) Early reaction to hypermobilitic injury in the synovial membrane is a proliferation of the surface cells and an increased capillary hyperemia.
(2) Fibrin deposits on the inflammatory synovial surface cells were noticed and parts showing the fibrin between closely apposed synoviums were indicative of fibrinous adhesion.
(3) A gradual change from fibrinous adhesion to fibrous adhesion was noticed.

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For the purpose of clarifying the influence of occlusal support areas on the masseter and temporal muscle activity, their EMG activity during isometric muscle contractions at the constant bite force was recorded with many subcutaneous needle electrodes and investigated.
The following results were obtained;
(1) The activity which the masseter and temporal muscle neccesitated for generating the same bite force varied remarkablly in individuals.
(2) In each occlusal support area, the muscle activity varied with the position of electrodes.
On the masseter muscle, antero-posteriorly, EMG activity of the middle or anterior part showed a tendency to be greater than that of the posterior one. Vertically, the activity of the lower parts tended to be greater than that of the upper ones.
On the temporal muscle, EMG activity of the anterior part was greater than that of the middle or posterior one.
(3) In each position of electrodes, the occlusal support areas being changed, the EMG activity had also changed.
The change pattern of the activity was nealy specific to each subject. Thit pattern varied remarkablly with the masster muscle, but slightly with the temporal muscle in dividuals and usually, occlusal support areas being changed from second molar to first premolar, EMG activity of the temporal muscle increased gradually.
(4) The activity of the masseter and temporal muscle increased when the bite force increased from 5kgf to 15kgf, and in subjects whose masseter and temporal muscle were recorded an inverse relationship was observed between their increase ratios.

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In this report, we propose our new clinical classification for temporomandibular joint disorders; MDO classification is as follows:
M-myofascial pain
M0 no myofascial pain
M1 presence of myofascial pain
D-internal derangement of TMJ
D0 no evidence of disk displacement
D1 disk displacement with reduction
D2 disk displacement without reduction
*D classification is additionally complicated by using the postfix “a, s, p, r, or n” which indicate the direction of disk displacement when that is confirmed using radiological or MR imaging.
O-osteoarthrotic change
O0 no osteoarthrotic change
O1 radiological evidence of osteoarthrotic change
Ex. Closed lock patients with muscle disturbance, but without osteoarthrotic change→M1D2O0
Using this classification, a clinico-statistical analysis of our patients was performed, showing that the patient's characteristics and the degree of dysabilities varied with the classification. We think that the MDO classification is not only useful in representing the state of each patient's disorder, but is also useful in expressing the severity of the disorder.

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The incidence of TMJ disorders in female college student was examined by questionnaire and oral examination. The subjects were 301 young female adults aged 18-23 years with a mean of 18.8 years.
The result obtained were as follows:
(1) Out of 301 subjects, 94 subjects (31.2%) had a primary complaint of TMJ dysfunction. 40 subjects (13.3%) had no complaint but they had an anamnesis of at least one symptom of TMJ dysfunction.
(2) No significant side differences were found on the TMJ symptoms.
(3) The most common symptom was TMJ sound (90.2%) followed by pain (30.6%) and abnormal jaw movement (21.6%).
(4) The most frequently observed TMJ sound was opening clicking in 66 subjects. Reciprocal clicking and crepitus were found in 10 and 3 subjects respectively.
(5) The incidence of TMJ was not dependent on Angle's classification.
(6) A significantly high incidence of TMJ dysfunction was found in subjects with crowding.
(7) A significantly high incidence of TMJ dysfunction was found the subjects who had a tendency to a unilateral chewing pattern and also in the subjects who had a habit of supporting their's cheek with their hands.

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Osteoarthrosis (OA) is defined as deterioration of articular cartilage layer of the joint components with exposure of bony structure. There are very few case reports of adolescent patients with OA, younger than 15 years old, in the literatrue. In this article, orthodontic treatment for an adolescent patient with temporomandibular joint osteoarthrosis was reported, and the changes of TMJ symptoms, TMJ pathological status, craniofacial skeleton and occlusion during and after treatment, are described.
This patient was a 13-year 5-month old girl, transferred from an orthodontic office, where she had been undergoing orthodontic treatment. She had a 6-year history of joint noise in both TMJs. Crepitation in both TMJs without pain was observed and the amount of maximum opening was 36mm. For the craniofacial skeleton, posteriorly positioned and small mandible and divergent mandibular plane were revealed. Differential diagnosis of the intraarticular pathosis by tomogram and MRI revealed bilateral osteoarthrosis defined as stage IV internal derangement of the TMJ according to Wilkes criteria, which indicated deformity and anterior displacement of the disk without reduction and severe resorption of the condyles.
After conservative therapy to increase the range of motion to 40mm, orthodontic treatment was continued to correct crowding. During treatment, however, crepitation of both TMJs continued and slight anterior open bite was still observed after treatment due to backward and downward rotation of the mandible, which is presumed to have some association with progressive resorption of the condyles. Posttreatment results were almost acceptable in terms of various jaw functions without pain and reduced range of motion.
It is thus suggested that patients with OA such as this case should be managed carefully during orthodontic treatment, because progressive condylar resorption may affect condylar position and occlusal stability during and after orthodontic treatment.

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To clarify the characteristics of dynamic responses of the mandibular fossa at the temporomandibular joint to mandibular movements, we performed mandibular movements in fresh human cadavers and measured strain by the tri-axial strain gauge method in the cerebral surface of the squamous part of the temporal bone constituting the upper wall of the mandibular fossa. The dynamic behavior of the temporomandibular joint was observed from the surface of the internal base of the skull. With changes in the route of mandibular movement and the mandibular position, bones in the upper wall of the mandibular fossa at the temporomandibular joint showed complicated changes in shape, In particular, the mandibular fossa sank in the direction of the external base of the skull with mouth opening but protruded in the direction of the internal base of the skull with mouth closing. These findings suggest that not only the articular disc but also bones constituting the temporomandibular joint buffer force applied to this area.

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The purpose of this study is to explain how the mandibular condyles displace during wearing of a stabilization biteplate.
Six normal stomatognathic subjects were examined. We made two stabilization biteplates for each subject, and adjusted the interincisal dimension to 2.0mm, and 4.0mm using a Mandibular Kinesiograph. Displacement of the condyles during wearing each of the plates was measured by computer axiograph.
The results were as follows:
(1) The more the stabilization biteplate increased the interincisal dimension from no plate (0mm) to 2mm and 4mm, the greater the amount of condyle displacement in the antero-inferior direction during wearing of the plates.
(2) The sites of condyle displacement during wearing of the plates coincided with the points of habitual jaw opening-closing movement.
(3) Relief due to wearing stabilization biteplates for the temporomandibular joint was confirmed.

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We investigate the changes of temporomandibular joint noise after initial non-surgical treatment, followed by intraarticular injection of hyaluronic acid or prosthetic treatment or orthodontic treatment.
97 patients were subjects for this study. 69 of 97 patients had TMJ noise episode with an average duration of 4.9 years. TMJ noise was divided into four grades by clinical findings and subjective symptoms. If a lower grade of noise was indicated after any treatment, it was descrdbed as “improvement”.
By initial treatment, including jaw excursion and muscle rehabilitation, 28% of patients improved their TMJ noises. 16 of 36 patients, whose interincisal length showed less than 30mm at first examination, had new noise after treatment.
The rates of “improvement” were 70% by prosthetic treatment, 33% by orthodontic treatment, 18% by intraarticular injection of hyaluronate, respectively.
TMJ noises occur in the early phase of joint abnormality sign as well in the recovery phase of the joint function. They needs treatment when they sturb the normal function and make subjects uncomfortable.

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