鯉下咽頭歯の1代目の歯胚は他魚の顎歯歯胚に似て粘膜上皮群が間葉組織内に肥厚増殖すること(歯堤)によつて形成されるが、2代目以後の歯胚は前記歯堤と萌出歯の根部表面を被う残存Hertwig上皮鞘の発育伸張した所謂補助歯堤との協同によつて形成される。

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A number of methods have been so far developed for the evaluation of human masticatory efficiency. Of these the most acceptable method seems to be the one based on the principle of screen analysis of solid particles of any material as crushed by a definite number of masticatory strokes. Such analysis, however, of particle size distribution of crushed material on screens of successive meshes naturally requires to be expressed in terms of more than one variable and makes it most difficult to evaluate the masticatory efficiency by means of any single numerical value. The use of a single mesh screen for sifting out the crushed particles, as proposed by Manly and others, for an evaluation of the masticatory efficiency also seems to have only very limited application. The use of several successive meshes of screen in an experiment, on the other hand, as proposed by Ishihara and by Ueda, has also disadvantage that it fails to elicit a common numerical value to express the efficiency of an individual mastication, and hence is inconvenient for the comparative study. In the present study, an attempt was made to obtain some significant information for estimation of the masticatory efficiency by calculating the net energy input required for the crushing of a material both in a specially designed mechanical apparatus and by the mouths of human subjects. The test material used for the crushing experiments was the same with the synthetic tablet as devised by Sato in this laboratory. The tablet was of a cylindrical form, 5mm in diametr and 3mm long, consisting of the mixture of equal volume of barium sulfate and Carnauba wax. For the purpose of model experiments, ten grams of the test tablet were placed in a steel mortar, and an iron ball weighing 2.7 kilograms was allowed to drop directly on the tablets one to four times to reduce them into respectively smaller sized particles. The mortar was held upon the base of hardened steel, and between the bottom of the mortar and the steel base were placed 3 pieces of aluminum cushion wire 1 cm long, being arranged radially with an equal angle of 120 degree between each other. These metal wires served to prevent the ball from bouncing at the drop by absorbing the impact, and furthermore served to provide a means to calculate an energy loss by measuring the amount of deformation produced on the wires by the impact. The net energy input required for the crushing of the tablets could be obtained in the following manner. The crushed material was packed in the cell of an air permeability apparatus, and compressed air was allowed to pass through the cell. Increments of the specific surface area of the material could be calculated from the pressure drop according to the equation as developed by Kozeny-Carman. The experiments conducted by the above procedures confirmed the usefulness of the test tablets in that there existed a first order proportionality between increment of the specific surface area and net energy input as evidenced in many previous experiments on other brittle substances. Similar experiments conducted on the test tablets after they were allowed to be mast-icated by human subjects also confirmed the applicability of this procedure to obtain a quantitative measurement of the masticatory efficiency in terms of net energy input. Since the above experiments using the air permeability apparatus were too time-con-suming to be applied clinically, an attempt was made to correlate the energy input data thus obtained to data obtainable by the conventional sieving method. For this purpose, a total of 22 subjects ranging in age from 10 to 55 with varying dental conditions from normal to denture wearer were selected as experimental subject. The test tablets were allowed to chew for these subjects, and the resulting particles of the tablets were analyzed by the two methods. Results showed that a significant correlation existed between 8-mesh oversize

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20 rats were given a certain quantity of india ink with 10% of its volume of gelatine-solution added to it by infusion through the aorta into the blood vessels of the mandibular bones, and the bones and surrounding tissue were made transparent by Spaltheholz's method for observation of the blood vessels. 1. It was found that there are three kinds of artery supplying the rat mandibular bone and teeth : the inferior alveolar artery and its molar branches passing through the accessory foramina of the alveolar processus, and mental artery. 2. The inferior alveolar artery supplies the incisor tooth and the third molar tooth and the molar branches supply the first and the second molar tooth. The mental artery supplies anterior root of the first molar tooth. These three kinds of artery have each a comitant vein. 3. Capillary anastomosis between the capillaries in the bone-marrow and those in the periodont of the molar teeth are often observed. 4. The periodont of the incisor tooth has much more vascularity than those of the molar teeth. 5. The venous drainage and vascularity of the incisor periodont are peculiar and complicated. The supeior one third of it is higher in vascularity than the middle one third, and the inferior one third, especially in its central part, has the highest vascularity. 6. There are five or six periodontal veins running parallel to the axis of the incisor tooth, one running along the superior margin, another along the inferior, two others along the lateral surface and the remaining two along the medial surface.

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For the selection of carcinostatic agents for clinical use, devising a useful susceptibility test has long been required. S.D.I. method as well as I.N.K. method as a susceptibility test there have been reports of Kondo et al., and Gomifuchi et al. Also in our Clinic S.D.I. and I.N.K. methods were followed as susceptibility tests, and the results summarized in Table (1-2) were obtained, using various carcinoma of the Oral and other regions which were removed from 35 patients who were operated upon at the Department of Second Oral Surgery, Kyushu Dental College and Kokura National Hospital. The data indicated that acording to S.D.I. method the most effective carcinostatic agent was Mitomycin C, and next Nitromin, Merphyrin, Toyomycin, Copp, Endoxan were arranged, according to I.N.K. method Mitomycin C, Toyomycin, Nitromin, Copp, Endoxan, and Merphyrin were arranged in order of the effectiveness. There was some difference in the order of the drugs in the two methods, but no remarkable difference in the rates of effectiveness. Therefore, attempting to increase the effect of the antineoplastic agents we investigated the coincidence of S.D.I. and I.N.K. methods in 16 clinical cases with various carcinoma, (including one sarcoma case) in which both methods were able to be carried out, among 35 cases above mentioned (Table 3). In this table (+) in S.D.I. method, (+) in I.N.K. method means "effective in both methods" and (-) means "non-effective in both". The data presented, in the order of the high coincidence of the carcinostatic agents. Copp, Endoxan, Toyomycin, Merphyrin, Mitomycin C, Nitromin. It is particularly important that the results of both methods coincide. The order of the effectiveness and the high coincidence of these drugs were Mitomycin C, Nitromin, Endoxan, Toyomycin, Merphyrin and Copp. A considerable difference between Mitomycin C with the highest effectiveness and Nitromin, the second, was observed. Our data was, however, obtained in vitro and it is doubtful if the results can also be applied in vivo. There is also another problem in the method itself in which the succinic dehydrogenase, the same system of the enzyme, was used both of S.D.I. and I.N.K. methods. Besides, the agents were applied to the cases before the test or not, and resistance against the agent caused by the administration for a long period of time, if any, were all neglected and the specimen obtained at operation was used for both of the examination, therefore, the difference of the results in vivo can not be denied. It should, however, be further examined how parallel the coincidence of S.D.I. and I.N.K. methods is to the clinical effect. For the first step of the solution of this problem, we investigated here on the coincidence of S.D.I. and I.N.K. methods.

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As a fundamentel experiment of the anticancer drugs, COPP, we have investigated on the influence of COPP on the growth of cultured cells and drug resistance. Mercury-hematoporphyrin was also studied as a control agent. For the estimation of the cell number, the unstained cell count method by means of 0.5% Eosin-P.B.S. was used. At the same time, the reduction ability of the succinic dehydrogenase in KB cells against T.T.C. (Triphenyl Tetrazolium Chloride) as an indicator was measured. The results obtained were as follows : when the anticancer drugs were applied to KB cells, the drugs used were effective in the high concentration, but in the low concentration, on the contrary, the drugs might stimulate the cells and cell growth appeared to be promoted, also KB cells seemed to be acquired the drug resistance following treatments with COPP 5-6 times.

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The human lower molars show different reductional characters in the evolutional process. It may be ment the fact that the primary characters represented at the past age in the phylogentic relationship, was brought as the morphology of some development changes in the human lower molars. These original characters which have been continued the changes in the human evolutional stage, may be appeared as the condition that have been represented in the past age or have not been queit appeared in the lower molar of the recent man. Namely, the original characters do not always appear as same reductional process, and further the appearence of the original characters be found as difference variation between the dentition of several racial group or between the dentition of the individual body. This report is result that was investigated about the frequency of the appearence in some original characters in the lower molar of the recent Japanese, and about correlation coefficients between each another character or between each aproximate tooth in a individual body. The original characters were investingated in the deciduous lower second molar as well as in the permanent lower molar, because the deciduous dentition have the original character more than in the permanent dentition and are smilar to the morphology of the permanent dentition. The characters examined are as follows. 1. Dryopithecus Pattern 2. Protostylid 3. Deflecting Wrinkle 4. 6th Cusp 5. 7th Cusp The result obtained on these investigation were summarized as follows. Five characters examined have been considered as the original characters, but these were found as a fairly reductional tendency on the lower molar of the recent Japanese. However, in comparison with other racial groups in regard to these characters, Dryopithecus Pattern showed the reductional tendency of same level with the White race, and showed the reductional tendency more than in the Negro race. But other characters were seen as more frequency than other racial groups. Namely, it will be considered as special original characters that were mainly appeared in Japanese population. Deflecting Wrinkle were seen pretty frequency of appearence about m_2 and M_1, but it were not almost seen the appearence about M_2, and it will be considered as the supposition that very difference type of the reduction of Deflecting Wrinkle between M_1 and M_2 have special meaning in the phylogentic relationship. In the correlation coefficients between each character, it were found to be differences of significant (under the 5% level) between Protostylid and 6th Cusp, and between Deflecting Wrinkle and 7th Cusp about m_2, and between 7th Cusp and Groove Pattern of the occlusal surface about M_2, however it were found to be almost insignificant about M_1. In the correlation coefficients between each aproximate tooth, Protostylid, Deflecting Wrinkle and 6th Cusp were found to be the difference of significant betewen m_2 and M_1. Protostylid and 6th Cusp were found to be the difference of significant between M_1 and M_2. Two characters obtained these significant correlation will be considered as had each one another some relationship on the phylogentie or on any other evolutional process.

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1) 遊離端義歯に加わる有害な側方推進圧をなくし義歯の機能時の安定を確保するため、筋圧維持法の術式を採用し、周囲の筋の機能運動に調和した義歯の外形を形成した。2) この様にすることにより、咀嚼時は勿論、談話その他の機能時においても鈎歯に加わる捻転力を最小にすることが出来、鈎歯の寿命を延長することが出来る。

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