There has been an increased interest in the radiography of the temporomandibular joint (TMJ) in the last several years. Even though newer imaging techniques, such as computed tomography and magnetic resonance imaging, are available, most of radiographs of TMJ are still made on film with a standard x-ray machine.
The routine x-ray examination for the lateral view of the TMJ is taken on the oblique lateral transcranial projection. The disadvantage of this method is often the superimposition of the bony mandibular joint component on the petrous bone.
The study was made on the so-called transpharyngeal projection. This projection give an excellent profile view of the condyle without superimposition of bony structures.
Medial part of the condyle seemed to be well demonstrated by transpharyngeal method, while lateral part of the condyle to be demonstrated by transcranial method on dry skulls.
Clinically a central x-ray was directed 10° ventro-dorsally and 10° caudo-cranially to the TMJ in 20mm mouth opening.
Radiation doses from the transpharyngeal radiographs compared favorably to those from the transcranial. The superficial structures at the point of entry absorbed the greatent amount of radiation in both techniques evaluated, while other tissues of interest, such as thyroid gland and lens of the eye, received much smaller doses.
The transpharyngeal TMJ radiography does not show the upper structures of the joint clearly and can not be used to examine relationships of the condyle between the articular eminence, and the articular fossa, thus drastically restricting its usefulness. It serves best auxiliary film to the transcranial series.

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In some tumors in the head and neck, radiation therapy is the treatment of choice to keep the oral function, while in others it may be used in conjunction with surgery or chemotherapy.
Radiation therapy, however, as any therapeutic process is not without side effect. The associated morbidity includes mucositis, epidermitis, xerostomia, radiation caries, pulpal damage and a reduced ability of the tissues to infection caused by various vascular and bone changes.
Patients receiving radiation therapy for oral lesions, specially including the salivary gland, usually develop xerostomia, a condition of decreased salivary potential with a resultant“dry mouth”.
The degree of xerostomia is directly related to the dose and volume of irradiated salivary tissue.
The purpose of this study is to examine whether the excretion of ^99mTc from the parotid can give any further information about the functional state of the gland and whether there are any correlation between sialography and RI-sialometry in degree of radiation damage in 43 irradiated cases.
I classified the xerostomia into Grade 0∼Grade III under the base of the patients complaints.
Grade 0: there are no influence at meal or conversation
Grade I: they feel suffering slightly at meal or conversation, but need not to drink water or milk to eat dry food.
Grade II: they feel pain at meal or conversation and need to drink much water to eat dry food.
Grade III: they need to drink water even at conversation and have dry mouth obviously.
85% of the patients who were irradiated whole parotid glands showed Grade II or Grade III, 14 of 15 cases (93%) who were exposed partially in the area of parotid gland showed Grade I. The degree of xerostomia in 17 of 21 cases (81%) who were totally 40 Gy exposed was Grade I and that in 20 of 21 patients (95%) who were more than 50Gy irrandiated was Grade II or Grade III.
From the present study it might be concluded that there is good agreement between the functional capacity of the investigated parotid glands recorded by sialography and RI-sialometry.
The classification by clinical complaints might be of value for evaluation of the functional capacity of irradiated parotid gland (xerostomia).
The histopathologic changes observed in irradiated parotid glands were in harmony with the clinical features of glands. In animal experiment, the same result was obtained.
The possible usefulness of RI-sialometry as a indication of radiation exposure is suggested.

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Clinical and radiological findings and subjective contrast of cystic border were examined on 13 cases of simple bone cyst pathologically established in this report.
The patients' average age was 22.3 years old and teen-aged patients were majority of the patients. Among 13 cases were 6 mules and 7 females, which did not show any difference by the sex. All these cases were seen at mandible and their radiographs showed scallop-shaped type under the teeth and round-shaped type at mandiblar ramus. Most of the cystic borders were clear and many of the Cyst inside showed even radiolucent images. There were cases with inter cystic partition or with radiopaque images. There was no bone expansion or border sclerosis seen in all cases. At the tissues adjacent to the cysts, there was a case which showed the enlargement of periodontal membrane space and in which lamina dura was thin, nil or thick. Other cases showed tooth root absorption or tooth fracture. When compared with the values of radicular cyst and radicular granuloma, the subjective contrast values of the cystic border showed similar ones to the latter.

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The absorbed doses in oral cineradiography were measured with thermoluminescent dosimeters at critical organs in the head and neck, and gonads. Rando phantom was used for this study. Pituitary gland, eye lenses, parotid-, submandibular-, sublingual-, thyroid-glands, and gonads were the sites for the measurement. The highest value was observed in the tube side of parotidgland in lateral view; 13.7νGy/frame. One of cineradiographic examinations was presented and the results were compared with that of the other clinical x-ray examinations.

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The purpose of this study was to clarify how the trabecular pattern of human jaw bone changes through a lifetime. This study may be useful not only for the diagnosis of oral diseases and diseases of bone metabolism as well as for the evaluation of their treatment but also interesting from the standpoint of forensic odontology.
In the present study, changes of the trabecular pattern followed up for 5 years were analysed with a computer imaging technique using intraoral roentgenograms of the lower incisor region.
As for the taking of roentgenograms, a standardized intraoral roentgenographic film holder was prepared for individual subjects to obtain a similar roentgenogram each time. The roentgenograms were taken once a year. A total 37 subjects were examined in this study whose age ranged from their teens to their sixties. The trabeculation was evaluated by recording the roentgenogram as a digital image on an image memory of 512×512×8 bits in size using a video camera followed by extraction of trabecular components from the band pass filtering of this image. The two dimensional crosscorrelation coefficient between initial roentgenogram and subsequent roentgenograms taken with elapsed time was determined and the trabecular changes were then expressed numerically. The results thus obtained were summarized as follows:
1. It was revealed that the correlation value of trabecular pattern on the intraoral roentgenograms over 5 years in each age group from teens to sixties slightly changed with aging.
2. Almost no change occurred in the mean correlation value of 5 years in each age group from teens to fourties but it changed to some extent in the fifties and sixties.
3. The trabecular pattern changed as a dissection of trabeculation or as a ranging of neighboring trabeculation but the whole bone trabecular never changed.
4. Since trabecular changes during a 5-years period seemed negligible judging from its correlation value, the trabecular pattern must be applicable for individual discrimination in forensic odontology.

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The eighteen cases of dentigerous type of pathohistologically established 18 cases of ameloblastoma and the 55 cases of dentigerous cyst were used as materials in this study. The author analyzed the distance from the cement-enamel junction of embedded teeth to the cystic wall attachment, in comparison with the distance between the junction and the root apex, and the area of radiolucent (cyst-like radiolucency). From the result of the analysis, the cystic wall attachment of ameloblastoma tended to be closer to the root apex than that of dentigerous cyst. As for the area, the ameloblastoma group had large and small areas but the area of the dentigerous cyst group tended to be small.
The area and distance of ameloblastoma group did not show any characteristics but those of dentigerous cyst group were inclined to show low values.

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Spurious components exist in Modulation Transfer Function (MTF) in intraoral roentgenography. We examined the influence of these spurious components on diagnosis in the present study. Materials and Methods
Spurious components may be caused by the bisecting angle technique and the focal spot size. The focal spot size was determined by pinhole roentgnography. In the case of the bisecting angle technique, a slit roentgonogram was taken by 10μm pb slit. From these roentgenogram, the MTF was determined. The influence of spurious components on diagnosis was examined as follows: Roentgenograms were taken by varying the object film distance. These roentgenograms were reduced to dental size and duplicated. These duplicate films were then examined by 11 dentists as to whether or not the diagnosis of periodontal space and laminadura could be made. As the object, the lower incisor region of dry skull was used.
Next, roentgenograms were taken by artificially changing the spurious gain. Referring to these roentgenograms, the relationship of spurious gain to inages of the periodontal space and laminadura was evaluated. Roentgenograms for evaluating were taken as below: A routine roentgenogram was first taken. Then, the object was laterally shifted about 100μm or 200μm with fixed film, and a roentgenogram was taken again. In this way, it is a type of double exposure technique. Results
It was revealed from this experiment that the spurious component exists between 5lp/mm to 10lp/mm in the MTF and that the influence on diagnosis was grestest when the gain was 0.5 or more. In these roentgenograms, the periodontal space appeared as double black lines and the laminadura as double white lines. In particular, the laminadura was found to be easily misjudged as hyperplasis in diagnosis.

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The purpose of this study was to clarify the influence of photon energy on the graininess of intraoral X-ray film. The photon energy was set at 10kV intervals from 40kV to 90kV. Total filtration used was 2mm or 12mm as the aluminium equivalent. Ag-particle size was determined microscopically by measuring the length on the X-axis of the particle image incorporated in the memory one-dimensionally. In order to compare with the graininess of screen film combination system, the particle size when X-ray film was exposed to visible ray from a fluorescent lamp was also determined. ULTRA speed film manufactured by Kodak Co. was used in this experiment.
Results: Among 10⁴ particle sizes thus determined, there were about 9 particles of 10μm in size from visible ray. On the other hand, approximately 10 particles were confirmed with 40kV, filter 2mm, 15 particles with 40kV, 12mm, 20 particles with 60kV, 12mm and 30 particles with 90kV, 12mm. When these particles were observed microscopically, it was revealed that the size of each Ag-particle was identical irrespective of the photon energy. However, a large mass of Ag-particle was found to be formed when the photon energy was high. Based on this evidence, the following conclusion could be drown:
Conclusion: In the case of screen film combination system, the film was sensitized with visible ray from the screen. In the case of intraoral X-ray film, on the other hand, the film was directly sensitized with X-rays. These findings may indicate that the latent image formation of Silver bromide grain is quite dissimilar between the two film types. It was also estimated that the mass formation of Ag-particles may be attributable to the scattered rays of secondary origin. The following schema represents a possible cause of radiographic mottle of nonscreen film.

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The alterations of the projected images on the rotational panoramic radiography were examined in six directions of a X-ray beam. A test object was placed at various positions in and around the image layer and the vertical and horizontal length of the projected images were measured.
The vertical length of the images decreased as the object was placed toward a film and no difference was found among six directions. The horizontal length increased exponentially as the position of the object was changed toward the X-ray tube. On the other hand, toward the film, it decreased slightly near the center of the image layer and increased slightly beyond it. This alteration was the most marked in the mid-sagittal direction and became less as the direction of the X-ray beam moved away from the mid-sagittal direction.
It was thought that the direction of the X-ray beam must be taken into consideration to recognize the alteration of the horizontal length of projected images.

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The nationwide survey in the frequency of dental radiography and the exposure factors was carried out with the cooperation of dental clinics, dental departments of general hospitals, and dental colleges of whole Japan in 1987.
The total number of dental radiography in Japan was estimated.
The results were as follows:
1. Dental x-ray units were used under the condition of 60kV and 10mA at almost all of dental clinics.
2. More than 85% of the dental x-ray units surveyed had open-end cylindrical cones.
3. The total number of intra-oral radiography taken in whole Japan was estimated to be about 9100×10⁴ and panoramic radiography was about 1140×10⁴ in 1987.

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The present study is based on clinical and roentgenological observation of 35 cases of odontoma that were encountered in past 4 years at Okayama University Dental School affiliated Hospital. The occurrence rate of the odontomas was 0.4% by roentgenographical evaluation of 8980 patients. They included 16 males and 19 females. The youngest patient was 7 years old and the oldest patient was 55 years old. The majority, 28 (80%), were compound odontomas and 7 (20%) were complex odontomas. Most of the compound odontomas had no inflammatory symptoms but the complex odontomas had caused inflammatory symptoms more frequently. The most common pathological sequel was impaction of neighbouring teeth with the prevalence of 74.3%. The most common location of the compound odontomas was in the upper anterior region and the complex odontomas occurred most frequently in the lower molar regions. The diameter of the size of the odontomas was usually between φ 11mm-15mm. The biggest was φ 70mm, and the smallest was φ 4mm.

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Swallowing disorder is one of the most serious dysfunctions followed by the maxillectomy. The purpose of this study is to elucidate the changes of swallowing process after operation using 35m/m cineradiography.
The patient was 36-year-old male who received a right total hemimaxillectomy because of malignant fibrous histiocytoma. Lateral and posteroanterior cineradiographs were taken during the swallowing of barium sulphate solution as the bolus. This cineradiographic examination was done periodically (before operation, in 3, 6 and 9 months after operation). The movements of oral structures, the tongue posture at the time point that the contrast medium reached the lower margin of mandible and transit time during oral and pharyngeal stages of swallowing were analyzed by using the cinefilm analyzer varying speed of the film.
In 3 months after operation, maintenance and passage of contrast medium deviated from the midline of tongue toward normal side. And the medium was swallowed little by little in oral stage. Consequently, overall transit time time became prolonged.
In 6 and 9 months, depression of tongue just after the start of swallowing became increased. As a result of increased tongue depression, passage of contrast medium was able to be done again on the midline of tongue and the contrast medium flowed down to vallecula as if water fall by the aid of gravity. Thus, timing of swallowing became closer to that of before operation.
From this study, it was suggested that alteration of tongue behavior, especially tongue depression, had an important role which might compensate the swallowing disorders following maxillectomy.

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