Nihon Ago Kansetsu Gakkai Zasshi最新文献

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.

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 cavity, and from the conjunctive area of the posterior slope of the auricular 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-laterally. The fiber bundles containing many elastic 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 stayed 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 obtain in this research. They were different from Ree's description.

Temporomandibular joint (TMJ) arthrography is a valuable diagnostic method to evaluate the pathology of soft tissue components of the TMJ. However, arthrography is more or less invasive technique. The aim of this study was to investigate the sort and content of injury following TMJ arthrography. The symptoms before and after the arthrography were compared. In 90 joints that underwent TMJ arthrography, complications such as pain and/or trismus were encountered in 39 joints within one month. Twenty six patients complained of the change of pain conditions including the discomfort. The most common one was the pain on mouth opening. In every joint the pain disappeared within one month without any treatment. There was a high frequency of exacerbated pain in patients with some pain before the arthrography. The change of the degree of maximum opening was recognized in 11 patients. The duration of that condition was somewhat longer than that of pain conditions. In 5 joints with late clicking, 3 developed closed lock. Other complications were swelling, disability of mastication, eczema, hearing impairment and facial paresthesia. All the symptoms disappeared within 1 week without any treatment. From these results it was suggested that TMJ arthrography has low possibility of severe damage to the TMJ although there is some possibility of injury to the bone and soft tissue by arthrographic procedures.

The condylar process is one of the sites predisposed to fracture clinical and experimental studies on the fracture mechanism have so far been undertaken by a number of our predecessor. However, the difference in the fracture mechanisms of intracapsular and extracapsular fracture has not completely been determined yet. In a Japanese Journal of Oral and Maxillofacial Surgery: Vol.32, 1362-1381, 1986: Shimada have previously reported the strong possibility that the direction and extend of fracture lines in the fracture of condylar process were influenced by the morphological characteristics of the condylar head. In order to verify this postulation, stress distribution patterns by the cross-sectional morphology of various types of condylar heads were investigated by two-dimensional finite element method, using 15 Indian edentulous mandibles. In this analysis, loading was applied to three directions in the model of the mandibular body, and two directions in the model of the mandibular head. The results indicated the following something. 1) With the loading in the direction of condylar head from mandibular angle, compressed stress arose on the condylar head with the surface. And with the loading in the direction of condylar head from chin and mandibular body, tugged stress arose on the condylar neck. 2) With the loading in the direction of vertical, these were conjectured that comminuted fracture arose on convex type, sagittal fracture arose on concave type and a style midway fracture arose on straight type. 3) With the loading in the direction of lateral, these were conjectured that fracture of condylar neck arose on the three types, especially the tendency was remarkable on straight type.

This study aims to analyse how jaw-closing muscle activities are modulated during lateral jaw movement. Jaw movements were recorded by Sirognathograph (Siemens Co.) and electromyograms were simultaneously recorded from bilateral masseter, anterior temporal and posterior temporal muscles in 20 young adults without any stomatognathic dysfunction. Each subject sat upright in the chair with the head unsupported. The lateral jaw movements from the intercuspal position were guided three times for each lateral excurtion (right and left). The data were recorded on magnetic tape and later analysed by use of a computer. Following variables were analysed; the number of contacted teeth, the position of contacted teeth, the muscle activities during lateral jaw movement. The results can be summarised as follows; 1) The working-side posterior temporal muscle showed obvious activity in more than 90% subjects during lateral jaw movement. However, this muscle activity was not influence by the number or position of the contacted teeth. 2) The right side masseter muscle tended to show the obvious activity during both right and left lateral jaw movement. The results of this study suggest the difference in the activities between masseter and temporal muscle during lateral jaw movement.

Inferior joint space arthrographies for the 37 patients with internal derangements of temporomandibular joint or joints were examined clinically. All arthrograms showed various problems of postural and morphological findings of the disc. Clinical diagnosis for the existence of internal derangements of the temporomandibular joint was completely confirmed by lower joint space arthrography. It must be considered, however, that clinical diagnosis for the morphological changes of the disc associated with internal derangements of temporomandibular joint is difficult. Inferior joint space arthrography was very useful to evaluate optically the discal formation in the cases.

In order to examine the relationship between the incidence of temporomandibular joint (TMJ) disorders and the occlusal problems, epidemiological surveys regarding the signs of TMJ disorders (joint noise, pain and disturbance of mandibular movement) were carried out to 149 untreated patients (54 males and 95 females) with malocclusion. The results indicated as follows: 1) Incidence of TMJ disorders was 33.6% of total samples, 27.8% of males and 36.8% of females. 2) In symptomatic subjects, the most frequent sign of TMJ disorders was joint noise (76.0%), the second was joint pain (68.0%) and the third was disturbance of mandibular movement (38.0%). 3) The incidence of TMJ disorders increased after 8 years of age, while it decreased slightly from 15 to 18 years of age and showed high frequency after 19 years of age. It was suggested that these changes were related with the occlusal configurations such as the exfoliation followed by the eruption of permanent successors or the eruption of the third molars. 4) Symmetrical anterior cross-bite malocclusion showed low incidence of TMJ disorders. In posterior cross-bite malocclusion and mandibular lateral displacement case, however, the signs of TMJ disorders were found frequently. These results suggested that the lateral shift of mandibular head in fossa may relate with the appearance of TMJ disorders.

Internal derangement of temporomandibular joint has been studied mainly arthrographically about disk position, but it was reported that morphologic alterations and histo-chemical changes of disk were frequently observed in joints with internal derangement. The aim of this investigation was to study the relationship between deformity of disk and the kind of internal derangement of TMJ (anterior disk displacement with or without reduction). We analysed arthrographically the configuration of anterior displaced disk according to the criteria of Westesson. Deformity of disk was seen in 35 joints in 60 joints (58.3%) associated with anterior disk displacement with reduction, and 51 joints in 66 joints (77.3%) without reduction. Statistically significant difference existed between the distribution of disk configuration in with-reduction and without-reduction. We analysed the relationship between distribution of disk configuration and age, clicking period and locking period. In cases long suffering from clicking and locking, no-deformed disk were seen, and any certain type of deformed disk did not increase. From above results it was suggested that there was a strong relationship between distribution of disk configulation and types of anterior disk displacement (with or without reduction).

The purpose of this study is to evaluate the relationship between orofaciocranial morphologic and functional factors. The lateral cephalograms of 10 normal subjects were taken and traced. The authors divided cephalometric parameters into linear and angular measurements. Electromyographic (EMG) activities were recorded from bilateral anterior temporal and masseter muscles during tapping movement. Then the total muscle activity of both muscles, and the masseter muscle activity ratio in the total muscle activity were measured. The correlation coefficients between cephalometric measurements and EMG parameters were analyzed. The results of this study are as follows: 1) The total muscle activity revealed positive correlation with all the linear measurements. Especially, the total muscle activity significantly correlated with the size of mandible, such as Co-Go and Go-Me. 2) The total muscle activity showed a tendency to increase when the angles among SN plane, FH plane, maxillary base plane and mandibular border plane became small, and when S-N-A and S-N-B became large. 3) There was no correlation between masseter muscle activity ratio and cranial morphologic measurments. But masseter muscle activity ratio correlated with tooth position and anteroposterior inclination of the anterior teeth. These results suggest that the consideration of the relationship between orofaciocranial morphologic factors and EMG parameters is necessary for examining the masticatory muscle activity.

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 occurred 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 rapidly progressed to osteoarthrosis.