This study investigated the diagnostic value of the anteroposterior (AP) arthrographic views of temporomandibular joints (TMJ) under X-ray fluoroscopic observations for patients with temporomandibular disorders.
We obtained AP arthrographic views of TMJ under fluoroscopic observations in 64 patients (85 joints) with temporomandibular disorders to evaluate the dynamic mediolateral information of the TMJ disk and the surrounding soft tissues in the opening and the closing jaw movements. The dynamic views of TMJ were recorded on videotape. The central ray of the X-ray beam was projected anteroposteriorly parallel to the median sagittal plane and 15-degree-angle to the Frankfurt horizontal plane up toward the head for the AP view of TMJ. As a result, AP arthrographic views of TMJ under X-ray fluoroscopic observations were valuable for diagnosing temporomandibular disorders, especially for diagnosing the mediolateral location of the fibrous adhesions in the superior and inferior articular cavities and the perforations of the disk in 38 out of 64 patients (59.4%). AP arthrographic views of TMJ under fluoroscopic observations were valuable to identify the three-dimensional locations of the pathoses in the articular cavities of TMJ with reference to the lateral views of arthrography. In contrast, those AP views provided no additional information concerning the dynamic movement of mediolateral-displaced disk. In conclusion, AP arthrographic views of TMJ under fluoroscopic observations were valuable to diagnose the pathoses in the articular cavities of TMJ.

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We report a case of osteochondroma of the mandibular condyle. In September 1992, a 43-year-old woman was referred to our hospital with chief complaints of spontaneous pain and noise in the right temporomandibular joint. Clinical examination revealed a slight swelling with tenderness at the right preauricular region and posterior open bite at the right side. Maximum mouth opening was 21mm and mandible deviated to the right side upon opening the mouth. X-ray, CT and MRI findings showed an enlargement of the right mandibular condyle of about 20×30mm. Scintigram showed an increased uptake of ^99mTc into the right mandibular condyle. On October 8 1992, under a clinical diagnosis of tumor of right mandibular condyle, condylectomy was performed under general anesthesia. The histopathological diagnosis was osteochondroma. When she was discharged, maximum mouth opening was 34mm and posterior open bite had been improved. The post-operative course has been favorable in the last 10 years.

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This study evaluated the relationship between age and incidence of disc deformity and bone changes in patients with anterior disc displacement without reduction of the temporomandibular joint. Two hundred and ninety eight joints of 215 patients, who had a normal dentofacial profile, were examined using magnetic resonance imaging with respect to disc deformity and bone changes. The incidence of these abnormalities was compared among different age groups. Pair matching was applied in order to match the sex ratio.
The incidence of disc deformity in the 30-39 years-old group (83.3%) and 40-49 years-old group (87.0%) were significantly higher than in the 10-19 years-old group (59.5%) and 20-29 years-old group (61.2%). The incidence of bone changes in 70-years-old group (70.8%) was significantly higher than in the 20-29 years-old group (42.9%).
The results indicate that the age is an independent factor for the incidence of disc deformity and bone changes in patients with closed lock.

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We investigated clinical characteristics and treatment outcome in 92 patients with condylar fracture of the mandible in our clinic from April 1992 to March 2002. The following results were obtained:
1. Condylar fracture occurred in 47.4% of the mandibular fractures and the ratio of males to females was 1.3: 1. The largest group of patients was the teenage group (28.3%).
2. The most frequent causes of condylar fracture were falling down (50.0%) and most patients (93.5%) visited our clinic within two weeks after injury.
3. Sixty-eight cases were unilateral (73.9%) and 51 cases (55.4%) were combined with other facial bone fractures.
4. Fracture with displacement and dislocation occurred most frequently in the condylar super neck region.
5. Sixteen cases (17.4%) were treated with surgical procedures, and 76 cases (82.6%) were treated with conservative procedures.
6. As for prognosis in 67 cases, 48 cases (71.6%) were completely healed, but 5 cases (7.5%) had functional problems.
7. Better clinical outcome was obtained in patients with unilateral fracture, under twenty years old, without severe displacement or/and dislocation.

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The clinical course of a 28-year-old female rheumatism patient showing a symptom of temporomandibular disorder as an initial symptom is reported. She visited our hospital in 1991 with chief complaints of pain and clicking on right TMJ during mastication and limitation on jaw opening. Her right TMJ was found to be articular disc displacement with reduction. A splint, muscle relaxant, or physical therapy had little effect on her mandibular function or TMJ pain. Osseous degenerative change was found in 1994, then progressive bony change resulted in anterior open bite in 1996. Occlusal stabilization was acquired by crown treatment in molar regions in 1998. At a regular check-up at an orthopedic clinic in 1999, her symptoms met the diagnostic criteria for rheumatism including a rheumatoid factor, an erosive change in an interphalangeal joint of the right thumb. From the findings above, she was diagnosed as rheumatoid arthritis showing initial symptom in TMJ.

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For a case in which manual reduction is difficult due to fibrous adhesion in the old anterior temporomandibular joint (TMJ) dislocation, open reduction has been carried out as one of the therapies. We present a case of an old anterior TMJ dislocation treated by manual reduction and by arthroscopic lysis and lavage. An 83-year-old woman was referred to the Maxillofacial Surgery Department, Shimane Medical University, School of Medicine with difficulty of mouth closing. X-ray films showed that the condyles were located in front of and superior to the articular eminence. At the first treatment, manual reduction had proved to be unsuccessful. Arthroscopic lysis and lavage were done under general anesthesia, and after treatment of them manual reduction of the condyles was successfully done. This result indicates that the method is excellent and can restore masticatory functions.

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Tetanus is a serious infectious disease caused by the tetanospasmin that Clostridium tetani produces. Because one of the early symptoms of tetanus is trismus, a patient complaining of this symptom may visit a dental clinic or a department of oral and maxillofacial surgery. We have examined five cases of tetanus with trismus as a chief complaint. They were composed of 1 man and 4 women, with mean age of 69.6 years. All patients had been preexamined in other medical institutions. However, none of the cases had been diagnosed as tetanus and 3 of the 5 patients had been diagnosed as temporomandibular joint disorders. The clinical symptom is the most important in order to diagnose tetanus, otherwise its bacterial identification or tetanospasmin has to be proven. Recently, many medical staff are unlikely to have encountered tetanus, making the diagnosis difficult. As the trismus of tetanus is very severe and more intense than that of temporomandibular joint disorder, the differentiation is not difficult if precise observation is carried out. It is therefore necessary to consider the possibility of tetanus when diagnosing and managing patients who have unusual difficulty in mouth opening.

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In order to develop an objective evaluation for the stability of the masticatory movement path in patients with temporomandibular disorders (TMD), 20 healthy subjects and 20 TMD patients were asked to masticate three types of food with varying textures. A piece of chewing gum, one peanut, and a slice of crispy bread were used as test foods. The movement of the incisal point while masticating the test food for 10 seconds on the habitual side was recorded. Ten cycles beginning with the fifth cycle of mastication were analyzed. The stability of the masticatory movement path was determined by calculating the SD/OD (standard deviation/opening distance) of the opening lateral component, closing lateral component, and vertical component. All results were compared between the healthy subject group and the TMD patient group. The masticatory movement path of the healthy subject group was more stable than that of the TMD patient group for all test foods. There were significant differences between the two groups in the opening lateral component (gum: t=4.78, p<0.01, peanut: t=3.73, p<0.01, bread: t=2.60, p<0.05), closing lateral component (gum: t=4.37, p<0.01, peanut: t=2.61, p<0.05, bread: t=2.97, p<0.01), vertical component (gum: t=6.25, p<0.01, peanut: t=3.15, p<0.01, bread: t=2.57, p<0.05) respectively. These results confirmed that the masticatory movement path of TMD patients is less stable than that of healthy subjects.

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Purpose: It remains a point of controversy whether or not evidence of joint effusion (JE) in magnetic resonance imaging (MRI) of temporomandibular joints (TMJ) may be linked to joint pain (JP). Previous studies had problems with the evaluation of pain because they compared JP between patients. Furthermore, JE had been evaluated subjectively by categories. In order to solve these problems, we quantified JE by MRI and designed a longitudinal study to compare JE and JP before and after arthrocentesis for TMJ. The aim of this study was to evaluate the relationship between JP and JE.
Patients and Methods: The subjects were 24 patients who underwent arthrocentesis for unilateral internal derangement or osteoarthritis of TMJ between January 1999 and June 2002. MRI was performed before and after arthrocentesis in all patients. The subjects consisted of 2 men and 22 women. Their mean age was 28.5 years (range 16-61). On T 2-weighted images, JE was identified as an area of high signal intensity in the upper joint space, and was evaluated on sagittal T 2-weighted images. We measured the area of JE using image analysis software (NIH Image) and calculated its volume by the expression:
Vol_eff=∑ (Ar_{eff. i}×ST) (Vol_eff: volume of JE, Ar_{eff. i}: area of JE in slice i, ST: slice thickness)
JP was evaluated using a visual analog scale (VAS). We classed patients into a pain improvement group and inefficacy group and an examined changes of JE and VAS in each patient before and after arthrocentesis.
Results: In the pain improvement group, 19 joints were improved, and in the inefficacy group, 5 joints were improved. JE and VAS of the pain improvement group significantly decreased after arthrocentesis. There was no significant difference in JE or VAS of the inefficacy group before and after arthrocentesis.
Conclusion: These results imply that a relationship exists between JE and JP.

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Immediate effects of low-level laser irradiation (LLLI), such as anti-inflammation and pain relief of temporomandibular joint (TMJ) disorders, have been reported. However, the molecular based mechanisms have not been elucidated yet. Synovial cells are believed to play pathological roles in the development and continuation of inflammation. Chemokines, such as interleukin (IL) -8 and monocyte chemoattractant protein (MCP) -1, have been found in synovial fluid from patients with TMJ synovitis as well as IL-1β.
This study examined the effect of LLLI on the production of chemokines stimulated in human synovial cells treated with IL-1β. The cells were isolated from TMJ synovial tissues and cultured using the outgrowth method. The confluent-stage cells were treated with IL-1β at the same time as LLLI was performed on the cells. The amounts of chemokines in conditioned medium were measured by an ELISA kit.
LLLI significantly reduced the production of IL-8 and MCP-1 in the early stage. These findings suggest that LLLI may have an anti-inflammatory effect on TMJ disorders through the reduction of chemokines production.

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This study proposed a simplified pathophysiological diagnosis for case of restricted mouth opening in TMDs, and examined the main pathophysiological sign of restricted mouth opening. It was reported that the main pathophysiological sign of restricted mouth opening was disc disorders, such as anterior disc displacement without reduction. Pumping and manipulation tend to be used as the primary treatment for restricted mouth opening to restore the grinding of the condyles.
Recently it has been shown that restricted mouth opening is caused not only by disc disorders but also by various pathophysiological mechanisms. Four items were proposed for simply classifying the pathophysiological signs of restricted mouth opening in TMDs. The four items were: 1) Muscular trismus type, 2) Disc disorder type, 3) Arthralgia disorder type; and 4) Muscular-Disc combined disorder type.
The main pathophysiological sign was examined as a way of applying the classification to 61 cases of restricted mouth opening. The examination showed that the muscular disorders type was the primary cause of restricted mouth opening.
It was suggested that pathophysiological diagnosis is essential for the treatment of cases of restricted mouth opening in TMDs.

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There have been reports on cases of concomitant mandibular and head movements during mastication and tooth tapping. In a previous report, we evaluated that normal healthy subjects had functional coupling between the head and mandibular movements during tooth tapping. However, little is known about the co-ordination of mandibular and head movements for patients with temporomandibular disorders. The objective of this study was to determine whether TMD patients had head movements accompanying jaw tapping. The results were as follows:
1. Some patients had head movements accompanying jaw tapping the same as healthy subjects, others had non-concomitant head movements with jaw tapping.
2. The incidence rate of concomitant head movement was 96.7% in the control group and 74.3% in the patients group.
3. The incidence rate in the patients group with limitation of mouth opening was 54.8%, which was less than those of the other symptom groups.

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