We report a case of an osteochondroma on the right mandibular condyle. A 62-year-old woman complained of something preventing her from opening her mouth, which condition she had noted for about six months, so she visited a dental surgeon. He found enlargement of her right mandibular condyle on X rays, and referred her to our hospital on. The maximum opening range was 36mm, complicating by pain and noise, in the primary examination. CT examination revealed a round, radio-opaque image of 5mm in diameter on the inside of the mandibular condyle. Surgery was performed under a clinical diagnosis of a mandibular condyle tumor, on. A bone-like tumor was excised from the inside of the mandibular condyle. On histopathological examination, thickened hyaline cartilage was observed under the fibrocartilage layer, and spongy bone was formed in the center of the tumor. It was diagnosed as an osteochondroma. Her complaints, and her opening difficulty with pain and noise, improved after the surery, and no symptoms of recurrence have been noted for 5 years.

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Medical records of 517 TMD (Temporomandibular Disorders) patients were investigated in this research (121 males and 396 females; mean age, 33.3±15.9years). These patients were examined as part of routine procedures at the TMD clinic, Department of Fixed Prosthodontics, Tokushima University Dental Hospital, from September 1989 to September 1996. Items in the basic TMD examination record of our clinic were the chief complaint, anamnesis, clinical history, present observations, radiological observations, diagnosis and treatment plan, etc. From the examination record, we focused on the chief complaint, anamnesis, clinical history, and present observations. The most frequent complaint was temporomandibular joint sound, then pain of temporomandibular joint and jaw muscles, limiting mouth opening. Medical records of 86 TMD patients, of ages from 21 to 25, were compared with 151 dental students of Tokushima University. Moderate and severe teeth attrition, and awareness of nocturnal bruxism, were found in TMD patient more frequently. Overjet of these patients was less than that of dental students.

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Recently, Degenerative Joint Disease (DJD) tends to increase in the elderly. But the relationship between loss of occlusion and DJD has not been examined. The purpose of this study was to clarify the effect on the form of the mandibular condyle by loss of occlusion in histopathological and histometrical observation. So, we used the Senescence-Accelerated Mouse P8//Ymi (SAMP 8//Ymi), which develops bilateral DJD at high frequency. Thirty male SAMP 8//Ymi were used in each age group of 2, 4, and 6 months old. Each age group was divided into milling groups (MG) and no milling groups (NG). In MG, the tooth crowns of the upper bilateral molar and incisor were milled to loss of occlusion. After two months, all animals were sacrificed, and the form of the mandibular condyle was investigated histopathologically and histometrically. Six-μm-thick serial frontal sections were made in the ordinary method and stained with hematoxylin and eosin, and PAS-Alucianblue. The measuring points were the horizontal and perpendicular lengths of the mandibular condyle, the layer thickness of articular and proliferation and cartilage cells on the cartilage layer. Moreover in the layer thickness of cartilage cells, the cell number was measured within the spaces of 60×70μm.
It was suggested that SAMP 8//Ymi given loss of occlusion encouraged a deformation in the mandibular condyle, further caused more serious DJD.

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The etiology of temporomandibular joint disorders remains unclear, despite recent progress in several diagnostic methods. To obtain more information on this disease, we performed a clinical evaluation of 1, 660 patients with temporomandibular joint disorders, who visited our department during the 10 years from January 1990 to December 1999. They were classified into 5 types based on a new classification proposal advocated by the Japanese Society of Temporomandibular Joint in 1996. The patients consisted of 478 males and 1, 182 females, and the ratio of males to females was 1: 2.47. The distribution of age groups had two peaks, in the 20s and 50s. The type distribution in our cases was as follows: Type III was most frequent (48.4%), followed by Type II (22.3%), Type I (19.7%), Type IV (9.2%), and Others (0.4%). The recent transition is that Types III, II and IV are increasing, but Type I and Others remain on the side level. And age transition is that twenties and fifties are increasing, but another ages remain on the side level.

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Two cases of metastatic tumor from the colon and lung to the temporomandibular joint (TMJ) are presented.
1. Panoramic and CT images demonstrated moth-eaten or irregular bony destruction and loss of the cortical layer of the condylar process, suggestive of malignancy.
2. MR imaging was valuable for visualizing the extent of lesions and differentiating benignity from malignancy of lesions in the TMJ. In this study, MR images revealed tumor mass involvement with an ill-defined margin on the TMJ. In addition, bone marrow signal changes were observed in the condylar process, indicating tumor involvement.
3. Radioisotope bone scanning has been determined to be more sensitive than conventional radiography in the detection of metastatic bone lesions.

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The present study was designed to evaluate the effect of FK 506 administration on endochondral ossification of the mandibular condyle. Ten SD rats were used. FK 506 was given intramuscularly, at a dose of 1.0 mg/kg/day for 28 days, for the FK group. The specimens were extirpated and examined 3-dimensionally using micro-CT, and histologically. As a result, the trabecular bone showed an osteopenic appearance in the FK group. The width of articular cartilage, especially the proliferate and hypertrophic zones, became narrower compared with the control group. From these results, it was suggested that FK 506 administration enhanced osteopenia of the condylar head through an effect on cartilage formation.

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Recently, temporomandibular disorder is discussed in commercial magazines and by mass media, and outpatients with temporomandibular disorder have increased in our hospital.
A previous review reported that patients with temporomandibular disorder were mainly of younger age group, but recently patients from any generation have appeared. At the junior high school boy and girl as second growth period, examination for temporomandibular is very important for an epidemiological survey of temporomandibular disorder. Then, we carried out measurement of maximal mouth opening and listening to sounds (click and crepitation) of the temporomandibular joint, and furthermore a questionnaire on a history of temporomandibular disorder and orthodontic therapy; bruxism, and life habits were evaluated in a dental examination at the same time.

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Objective: To assess the effectiveness of magnetic resonance imaging (MRI) for the diagnosis of rheumatoid arthritis (RA) in the temporomandibular joint (TMJ), MRI was performed on RA patients with TMJ involvement.
Methods: Six patients (all women) with TMJ involvement, of average age 49.8 years (range 24∼70), who had been serologically or clinically diagnosed with RA by orthopedists, were enrolled. Diagnostic imaging included plain radiography (panoramic radiography and lateral oblique transcranial projection), multisection tomography, and MRI, such as Proton density MRI, T1-weighted MRI and T2-weighted MRI. On each examination, bone changes of the TMJ and soft tissue in the TMJ were evaluated.
Results: MRI showed that 9 of the 12 joints had bone changes, including erosion and osteophyte; disks were invisible in 5 joints; disks were superior to the condyle in 6 joints, and one disk had anterior disk displacement without reduction. On T2-weighted MR images, 5 joints had high signal intensity. Only one joint was suspected of having pannus.
Conclusion: It was concluded that the effectiveness of visualizing bone changes of the TMJ by MRI was similar to that by conventional radiographic examination. MRI also visualized abnormal soft tissue in the TMJ. Thus, MRI might be a useful technique for evaluation in RA patients.

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To evaluate the efficacy and safety of RAK-591 in the treatment of patients with temporomandibular joint disorders, RAK-591 was orally administered, at a dose of 200mg, twice daily, for 4 weeks. In a total of 101 subjects, the efficacy was evaluated in 86 cases, and safety in 90 cases. The improvement rate of pain on exercise (including “improved” or better) was 45.0% (36/80 cases) after 2 weeks, 50.0% (29/58 cases) after 4 weeks, and 57.0% (49/86 cases) at the end of medication (49 improved cases consisted of 16 completely improved cases at 2 weeks, and 33 improved-or-better-rated cases at 4 weeks). The pain on exercise on VAS was 51.8mm on average before administration, and 16.1mm on average at the end, showing a significant reduction (p<0.001). The maximal range of passive and pain-free opening expanded from 32.9mm, on average, before administration, to 41.4mm, on average, after 2 weeks, and 42.6mm, on average, at the end, indicating significant improvement (p<0.001). On the other hand, adverse reactions were observed in 17 of 90 cases (18.9%), but none were serious. The main adverse reactions were gastrointestinal symptoms, and these recovered after stopping the medication without any treatment.
In conclusion, RAK-591 exhibited good clinical efficacy and high safety in the treatment of temporomandibular joint disorders, and it was considered to be a useful drug.

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This case report describes orthodontic treatment of skeletal open bite with temporomandibular joint disorders and left mandibular shift. At the initial examination the patient was a female of age 18 years and 8 months, with a chief complaint of TMJ sounds. It was deemed difficult to improve the TMJ sounds but necessary to improve occlusal function, by orthodontic treatment. Maxillary first premolars, maxillary second molars, mandibular first premolars, and mandibular third molars were extracted. After orthodontic treatment, TMJ sounds on the left side disappeared, but TMJ sounds on the right side remained. On MRI, the left TMJ articular disc was nomal, but the right TMJ articular disc showed anterior dislocation with reduction. The disorders of occlusal function were improved.

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Extrapyramidal disorders in cerebral diseases, such as Parkinson's disease, have been noted to cause temporomandibular joint dislocations. We describe here surgical treatment for two cases of recurrent temporomandibular joint dislocation associated with cerebrovascular disease.
Case 1: A 68-year-old man visited our hospital with the chief complaint of left temporomandibular joint dislocation. He had had a cerebral infraction and exhibited cerebrovascular dementia and Parkinson's disease. Blocking of the condylar translation was performed by LeClerc's procedure for the zygomatic arch. Shortening of the oral mucosa and temporal tendon was also performed.
Case 2: A 40-year-old women visited our hospital with the complaint of right temporomandibular joint dislocation. She had had a cerebral hemorrhage and paresis. LeClerc's operation was performed as the primary treatment. Since the temporomandibular joint dislocation recurred 3 months after the operation, she underwent bilateral shortening of the oral mucosa and temporal tendon.
For good prognosis of recurrent temporomandibular joint dislocation in patients with cerebrovascular disease, the treatment method must be selected based on the patient's and family's social background, the patient's general condition, and radiographic diagnosis.

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There have been many reports on Dental Prescale^® (Prescale, Fuji Photo Film Co. ). However, few reports have referred to “the percentage of measurable contact area, ” which is the ratio of the occlusal contact area generated by the measurable occlusal pressure to the total occlusal contact area in the Prescale system. The purpose of this study was to investigate the distribution of “the percentage of measurable contact area” at maximal clenching, and to clarify the relation between “the measurable contacts rate” and the total contact area. Subjects were 25 healthy dentulous people and 30 dentulous patients with temporomandibular disorders (TMD). Each group was classified into the following 3 subgroups according to occlusal contact area: less than 20mm², 20∼40mm², and more than 40mm². Prescale 50H type R was used for measurements. The following results were obtained. 1) The means of “the percentage of measurable contact area” in the healthy group and the TMD group were 99.0±1.3% and 98.9±1.7%, respectively. There was no significant difference between the two groups. The percentages of subjects whose “percentage of measurable contact area” was 100% were 23.3% in the healthy group and 25.6% in TMD group. 2) There were significant correlations between “the percentage of measurable contact area” and the total contact area both in the healthy group and the TMD group. In the healthy group, “the percentage of measurable contact area” of the subgroup of less than 20mm² was significantly lower compared with the other two subgroups. In conclusion, it became clear that, mostly, “the percentage of measurable contact area” at maximal clenching in dentulous people is 100% or approximately 100%, and that “the percentage of measurable contact area” becomes lower when the total contact area is small. It was suggested that we need to take the value of the total contact area into consideration when we use Prescale.

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This report shows treatment for a patient in the growing period with temporomandibular disorder (type-IIIa) with complications, skeletal open bite, and abnormal oral myofunction.
We obtained favorable results from a sequential approach that began with stabilizing the condition in the temporomandibular joint to myofunction, and finished up with improvement of occlusion. To improve the jaw relationship, anterior repositioning splint therapy, which has a possibility of causing undesirable conditions, however, was eventually able to bring about good effects on all the conditions, by making following approaches to the temporomandibular joint easier.

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A diagnostic procedure in crystal deposition disease of the temporomandibular joint (TMJ), and a method for detection of crystals in the joint fluid, were studied. Five cases of acute arthritis of the TMJ were examined. These cases were suggested to be suppurative arthritis of the TMJ, based on clinical signs, showing apparent swelling and severe pain, and based on radiological findings. However, no microorganisms were detected in the joint fluid. Therefore, we next examined crystals in the joint fluid, employing polarized light microscopy and an electron probe micro-analyzer (EPMA). Calcium pyrophosphate dihydrate crystals were detected in 2 cases, and thus the lesion was diagnosed as CPPD crystal-induced arthritis of the TMJ.

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