Oncocytes, epithelial cells characterized an abundant, granular and deeply acidophilic cytoplasm, are found in a variety of organs. Generally, oncocytes occur singly or in small clusters and appear to increase in frequency with advancing age. These cells can be found not only in normal salivary gland tissue but also in many tumors, and several salivary gland tumors (Warthin's tumor and oncocytoma) consist primarily of oncocytes. While the morphology of oncocytes in neoplasm of the salivary glands and in normal salivary glands had been characterized, there are very few studies about the systematic examination of oncocytes in normal salivary glands. And the genesis and the biologic significance of oncocytes remain still obscure. In this study, the appearance and the histological pattern of oncocytes in human palatine salivary glands have been examined systematically, and the possible mode of development and the significance of these cells are discussed. The results were as follows : 1) One hundred and sixty four cases of clinically normal palatine salivary gland obtained from autopsized patients of various age, were histologically investigated for oncocytes. These were unselected persons who died of various diseases. Oncocytes were found in 143 persons (87.2%) who ranged from 2 months to 83 years of age. Oncocytes were observed in a few cases before the age of twenty, occurring thereafter most commonly and in greater number in elder cases. The frequency was slightly higher in males than in females. 2) The frequent presence of oncocytes was noted in the canalicular system, especially in large intralobular ducts and interlobular ducts followed by smaller intralobular ducts and acini. These cells were found less often even in the excretory ducts. 3) Oncocytes were usually seen in several areas of the sections studied from each case. As for the location of oncocytes appeared in many cases, they were distributed widely and were noted to increase in distribution with age of the individuals. 4) In both ducts and acini, oncocytes were generally gathered in small groups, but also occurred singly. Some of ducts lined by oncocytes were dilated and contained eosinophilic granular materials, and others showed infolding and stratifying of these cells. These multiplicated patterns of oncocytes in the duct wall were more frequently found in the cases over 50-year-old. 5) In 67 of 143 oncocyte-positive cases (46.9%), the oncocytes appeared to form areas of the probable proliferation including the various patterns, that is, stratification, cyst formation, papillary projection, adenoma-like lesion and groups such as microtubular or acinar appearance. Sometimes several areas of these proliferative lesions of oncocytes were seen in different fields in one section. And such foci were found more frequently in older cases. 6) It was not possible to observe the definite relation between the presence of oncocyte and the other histological change of palatine salivary gland such as glandular atrophy, inflammatory change, regenerative process and so on. 7) From the above-mentioned histological investigations of the oncocytes of palatine salivary glands, it is assumed that the occurrence of oncocyte has some relationship with the aging. Furthermore this possibility is enhanced by the observations that oncocytes not only appeared in increasing number with advancing age, but also more widely distributed and more frequently showed the proliferative lesions in older cases. Because of the fact that the appearance of oncocyte was no relevant to any pathohistological changes of palatine salivary gland such as atrophy, it is assumed that the development of oncocyte would be influenced by the systemic factors rather than the local factors. So, in order to clarify the genesis and the distinct significance of oncocyte, it is necessary to investigate further the occurrence of oncocyte in other salivary glands of

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The temporomandibular joint plays an important role in dental medicine. Therefore, studies of morphology and function of the temporomandibular joint or study of pathogenesis of temporomandibular joint dysfunction have been carried out in special field of dental medicine. In the field of radiology, some investigations have been made on morphology of the mandibular fossa from the radiological view points. In this study, the shape of the mandibular fossa revealed by lateral oblique radiograph was expressed as a single function using Fourier Progression. The study was done of 82 females (from the second decade to sixth decade) who had negative radiographic findings of temporomandibular joints. The radiographs were divided into five groups at every decade, and each group was compared on differences in the side and age. The results obtained are as follows : 1. Morphologic differences between the right and left mandibular fossae were seen in the third, fifth and sixth decade. The cause of differences are due to that the anterior part of the left mandibular fossa was deeper than the right side. 2. Morphologic differences of the right mandibular fossa, in regard to aging, were seen in the comparisons of the second and third decade, the third and fourth decade, and the fourth and fifth decade. Similar figures of morphology were seen in the other comparisons of the individual decade, except above three combinations. 3. Morphology of the mandibular fossa changes remarkably between the second and fourth decade ; i. e., the anterior part of the mandibular fossa of the third decade was shallower than the second decade, and the posterior part was deeper than the second decade. At the fourth decade the mandibular fossa was shallower than the third dedade, especially in the posterior part.

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All the casting prepared for the present experiment could not be produced without any shrinkage and deformation. Although asbestos lining surely decreased the cast shrinkage, the casting could almost never become larger than the wax pattern. Under the circumstances the conventional crown model of the casting, of which the core height is three quarters of the outer side wall height, could have larger concave than the wax pattern by lining the ring with two folds of wet asbestos or more. Such a deformation favorable for the good fitness may possibly be caused by larger size of the core. Results of the pressure measurement on the pattern in the investment revealed that the anisotropic and heterogeneous setting expansion of the investment in the casting ring would be induced by the presence of the wax pattern itself. The investment is partitioned by the pattern into two parts, the core portion and the portion between the pattern and the ring wall. Each portion of the investment would seem to behave somewhat independently in setting. The well fitting of the crown casting may be attributed never to the full compensation for the cast shrinkage, but to the favorable deformation caused by the beneficial expansion of the core and the impediment of it to the free contraction of the cast alloy in solidification.

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Many radiographic techniques are usually obtained for detection of mandibular fractures ; i.e., there are periapical projection, occlusal projection, oblique or postero-anterior projection of the mandible, panoramic radiography, etc. The purpose of this study is to compare the diagnostic accuracy of each radiographic technique, such as oblique projection, postero-anterior projection, and orthopantomography. The results obtained are as follows : 1. Postero-anterior projection of the mandible is an adequate technique for the detection of fracture of the symphysis. 2. Oblique projection of the mandible is an adequate technique for the detection of fracture of the mandibular angle. 3. Orthopantomography is an excellent technique for the detection of fracture of the mandibular body and condylar process. 4. Although the orthopantomography has some weak points, but it is a better radiographic technique than the other two projections as far as the detection of mandibular fractures.

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This paper gives identification of tooth category on the lower insisor. As the method the authors have led the discriminant function. The materials were used the lower insisor of 200 numbers (100 lower central insisors and 100 lower lateral insisors). All of them belong to the department of oral anatomy, Kyushu dental college. The measurement has been made on five items (X_1 : mesiodistal diameter of crown, X_2 : labiolingual diameter of crown, X_3 : mesiodistal diameter in cervical line, X_4 : labiolingual diameter in cervical line, X_5 : root length) in each tooth. The essential points of the results obtained were as follows. 1. The lower insisors showed clearly significant difference of tooth category (at the level of 1 percent). And the lateral incisor was larger than the central insisor in all items. 2. The root length indicated the most value on the difference between means, the difference of tooth category and the ratio between both teeth. Moreover, the coefficient of variation of the root length was the largest value in five items (table 2.). 3. The discriminant function was led, that is, Y=0.021847X_1-0.010859X_2+0.000422X_3+0.023674X_4+0.005055X_5. The discriminant value was 0.256189. The practical method is as follows : comparing Y with the discriminant value, if the former is larger than the latter, the tooth regarded as the lower lateral insisor, and in the reversal case it would be the lower central insisor. 4. The probabilities of misclassification in this way was 11 percent. 5. As a whole, the discriminant function, as a method of identification of tooth category, especially the lower incisor, is much more useful than the other method heretofore in use in its objectivity, simplicity and accuracy.

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