Asymmetry of the shape of the bilateral condylar heads is fairly common even without degenerative bone change of the condyle with temporomandibular joint disorders (TMD). So, the purpose of this study was to evaluate the relation between the morphology of the condylar head without degenerative bone change and the disk position. One hundred and fifty-four TMJs were analyzed. All subjects were female patients, and were classified into three groups by disk position using arthrotomograms. The three groups were; normal disk position (NP), anterior disk position with reduction (W), and anterior disk position without reduction (WO). The morphology of the condylar head was measured using CT. The larger the displacement of disk position, the smaller the maximum cross-sectional area of the condylar head and the shorter the long axis and short axis of the condylar head. On the other hand, the horizontal condylar angle of the WO group was wider than the NP group. However, , the long axis-short axis ratio was not different. In the W group, the longer the duration from the onset of some symptoms, the smaller the maximum cross-sectional area of the condylar head, and the wider the horizontal condylar angle. The WO group did not show the same results. Accordingly, disregarding degenerative bone change, it was concluded from there results that the morphology of the condylar head with TMD changed, but irregularly.

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108 patients with reciprocal click who were subjected to no treatment or only medication were followed by questionnaire for 2 or 5 years. The results were as follow;
(1) The rates of progress of closed lock were 17.4% (2-year followed group) and 19.4% (5-year followed group).
(2) The click disappearance rates were 34.8% (2-year followed group) and 25.8% (5-year followed group).
(3) Painfull click at the initial examination developed closed lock more frequently than painless click.
(4) 17.6% (2-year followed group) and 6.9% (5-year followed group) of the patients who had painless click complained of joint pain.

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The purpose of this study was to clarify the relationship between clinical history and morphological changes of the temporomandibular joint structures in patients with internal derangement. Seventy-five patients (86 joints) arthrographically diagnosed as anterior disk displacement without reduction were divided into four groups according to their clinical history before closed-locking, such as joint-sound and joint-pain. Clicking sound in mouth-opening and/or closing was always noticed during some periods in 38 joints of 35 patients (reciprocal clicking group). Seventeen patients sometimes had clicking sound in 21 joints on various mandibular movements (other clicking group). Fourteen patients noticed crepitation in 17 joints (crepitation group). No sound was experienced in 10 joints of 9 patients (no-sound group). Age, duration of closed-lock, symptoms, clinical history, arthrographic findings and several other findings were investigated and compared among these groups.
(1) The average age was 32.7 years in the reciprocal clicking group, 44.2 years in the other clicking group, 41.4 years in the crepitation group and 36.6 years in the no-sound group. There was a significant defference between the reciprocal clicking group and the other clicking group.
(2) In the reciprocal clicking group, the patients had similar clinical histories: TMJ locking followed painless clicking. On the other hand, the patients in the other groups had various clinical histories.
(3) In the reciprocal clicking group, no adhesion in the upper joint cavity was seen in 22 joints (57.8%) and the condylar shape was flat in 20 joints (52.6%). In the other group, the morphological changes were more advanced than in the reciprocal clicking group: severe disk-adhesion was seen in 42.8-70% of the joints. Moreover, the articular surface of the condyle was erosive in 50-64.7% of the joints.

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Much attention has been paid to the relationship between osseous changes of the condyle and the intra articular findings of the lower space of the temporomandibular joint. We developed an ultra thin solid fiber scope for viewing the lower space of the temporomandibular joint. The diameter of this scope is 1.06mm and the endoscope cannula is 1.48mm in diameter.
However, this scope contains 15, 000 image fibers. The arthroscopic examination was performed in cases with disk displacement without reduction and which were refractory to non surgical treatment. Then, the arthroscopic findings were compared with MRI and arthrography. The first needle was inserted into the lower space under fluoroscopy and the contrast medium was injected to confirm the lower space. The arthroscope was penetrated into the lower space and the first needle was used for the out flow. Pathological findings such as adhesion, osseous changes, perforation and synovitis were able to be clearly found in the lower space through the arthroscopy.

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Twenty-five cases with condylar fractures of the mandible in teenagers, treated at our department from January 1988 to December 1993, were evaluated.
Their characteristic features were as follows;
(1) There were 15 males and 10 females. The ages of the patients at the time of temporomandibular joint (TMJ) fracture ranged from 14 to 19 and the average was 17.4 years old.
(2) Eighteen cases (72.0%) were unilateral fracture and 7 (28.0%) bilateral. Nineteen cases (76.0%) were complicated by other mandibular fractures.
(3) Of 32 condyles, 14 (43.8%) condyles were treated with surgical procedures. As for osteosynthesis, condyles were fixed with Kirschner's pin in 6 condyles (42.8%), intraosseous wirings in 4 condyles (28.6%), and miniplates in 4 condyles (28.6%).
(4) Intermaxillary fixation were performed in 24 cases (96.0%) and the average period was 18.7 days (ranged from 10 to 37 days).
(5) At 6 months after the treatment, the results of follow-up examination were satisfactory and there was no difference in clinical findings between surgical and non-surgical procedures.
(6) We compared the condylar position before and after the treatment by Mento-Vertex (axial) cephalogram examination. As a result, most condylar positions in the surgical group were improved to a state closer than the ones in non-surgical group to the original anatomical position.

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A prognostic investigation was undertaken on twenty-two TMD patients with only reciprocal clicking noise. The purpose was to understand the association between the prognoses, which were no clicking noise, reducing noise and no change, and the contributing factors, such as duration of noise, type of treatment procedure, duration of treatment, occlusal factor, parafunctional habits and psychological factors.
The results were as follows;
In a comparison of the above mentioned prognostic groups with each other, the group with no changed clicking had a longer duration of clicking history than the group with no click (p<0.05).
No significant difference, however, was found in the other factors.
No significant difference was found between the group with only click (22 cases) and the group with clicking noise with pain (36 cases) or the group with closed lock (19 cases), as to the occlusal factors and parafunctional habits.
At the time of recall of twenty-two patients, no cases were observed which become to have painful or to have fallen into closed lock.

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We successfully performed a new surgical procedure, arthroscopic surgery after intermaxillary traction in a case with chronic rheumatoid who had subsequent arthrosis deformans of the temporomandibular joint (TMJ) and malocclusion. The patient, a 60-year-old female, had had chronic rheumatism for approximately 20 years and complained of masticatory disturbance. She had an open bite of 8mm between the edge of the anterior teeth, and could occlude only on the 2nd molars in denturous jaws. X-ray findings showed marked absorption deformation of the mandibular head and deformity of the bilateral articular discs, fibrous adhesion and narrowed cavities double contrast of the bilateral TMJ. Intermaxillary traction was performed on the anterior teeth using pivoting splint on the molars to extend the intraarticular space, and the open bite disappeared. Then the articular disc and surrounding tissues were arthroscopically sutured and fixed to be thickened so that the condyle and mandibular fossa fit well. During the two postoperative years, x-ray revealed remodeling bilateral mandibular heads and the patient has been doing well with improved occlusion.

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There are many controversies on the mechanism of anterior disk displacement, but there is general agreement that laxity of capsular structures is involved. Increased laxity in the systemic joint may lead to internal derangement of the TMJ and worsen the prognosis for conservative treatment of the TMJ.
Therefore, systemic joint laxity should be taken into consideration in diagnosis and treatment of internal derangement of the TMJ.
We investigated the association between the severity of anterior disk displacement and systemic joint laxity among female patients.
MR Imaging identified anterior disk displacement, and the modified criteria by Beighton, et al identified systemic joint laxity.
The results of examination were as follows;
(1) The joint laxity of patients with anterior disk displacement without reduction (A. D. N. R.) was significantly higher than that of normal subjects and patients with anterior disk displacement with reduction (A. D. R.).
The incidence of hypermobility in patients with A. D. N. R. was significantly higher than that of the other two groups.
(2) The disk position of patients with A. D. N. R. whose joint laxity was higher was significantly much more anterior than that of A. D. R..
(3) The articular disk morphology of patients with A. D. N. R. was changed severely, and there were few disks with normal shape.
On the other hand, many of the patients with A. D. R. had normal shapes articular disks, and a few patients had disks with changed shape.

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Clinical studies of temporomandibular sounds without disk repositioning mandibular position were performed in 25 patients with internal derangement (male: 8, female: 17) by using single contrast arthrotomography (sagittal and coronal section).
Results;
(1) There were cases of normal disk position, medial displacement of the disk, posterior disk displacement in mouth opening, anterior disk displacement only in the closed mouth (with reduction) and anterior disk displacement in the closed mouth and in mouth opening (without reduction).
(2) In the joints having normal disk position, the sound occurred between the articular eminence and the superior surface of the disk, the so called eminence click. They had fibrous band-like adhesion in all cases.
(3) In the joints having posterior disk displacement in mouth opening, deformity of the disc and fibrous adhesion in the superior and inferior joint compartment were observed.
(4) Although the joints of anterior disk displacement with reduction typically have disk repositioning occlusion, the cases without it showed deformity of the disk and fibrous adhesion in the superior and inferior joint compartment.
(5) Although the joints of anterior disk displacement without reduction have typically no sounds, the cases with crepitus showed deformity and perforation of the disk or fibrous adhesion in the superior and inferior joint compartment. They also showed osteophyte change of condyle with no observed trismus.

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Intra-articular administration of sodium hyaluronate is regarded as an effective therapy for temporomandibular disorders presenting limited mouth opening or arthrodynia, but the tran sportation of administered sodium hyaluronate to the surrounding tissues is unknown. In this study, fluorescein-labelled sodium hyaluronate was administered into the upper joint cavity of the monkey temporomandibular joint (TMJ), and fluorescence in the synovial fluid of the upper and lower joint cavity was examined immediately, then at 6 hours, 24 hours and 72 hours after administration. Then the TMJ was resected, and was fixed with neutral formalin containing 0.5% CPC, and a cryospecimen was prepared after decalcification with EDTA. Observation was carried out light microscopically under HE staining, and fluorescence distribution was examined with a confocal laser scanning microscope. Sodium hyaluronate administered into the upper joint cavity of the monkey TMJ disappeared from the joint cavity 72 hours after administration.
Transportation of administered sodium hyaluronate from the upper to the lower joint cavity through the articular disc or postdiscal connective tissue was hardly observed. The result suggests that sodium hyaluronate should be administered in the upper and lower joint cavity of the TMJ for the effective therapy of temporomandibular disorders.

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This study was designed to evaluate tenderness in patients who were examined for tempormandibular joint (TMJ) disorders, as a part of team approach to the treatment of TMJ disorders at Tsurumi University. One hundred twenty patients were examined between June 1991 and February 1995. Sixty-seven (55.8%) of these patients (10 males, 57 females, mean age 41±18 years) had tenderness. The tenderness was assessed at 14 sites. It was on the ipsilateral side more often than on the contralateral side, and many patients had it in two sites. According to the classification of TMJ disorders in the Japanese Society for TMJ, tenderness was most frequently noted in the following sites: class I-posterior aspect of the ramus including the digastric muscle, shallow part of the masseter muscle, anterior temporal muscle, and sternocleidomastoid muscle; class II-condyle area; class III (anterior disk displacement with reduction) -posterior a spect of the ramus including the digastric muscle, shallow part of the masseter muscle, and anterior temporal muscle; class III (anterior disk displacement without reduction) -condyle area and shallow part of masseter muscle; class IV-posterior aspect of the ramus including the digastric muscle, shallow part of the masseter muscle, and anterior temporal muscle.
The results of this study indicated that although there was no clear-cut relationship between the Japanese classification of TMJ disorders and the sites of tenderness, there were specific sites of tenderness associated with the TMJ disorders.

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