For establishing the standerds to judge masticatory efficiency in denture wearers, the author made experiments on healthy 20-year-old 20 males with normal teeth by the method was an improvement on Kobayashi's method that pays attention to amylohydrolytic activity of salivary amylase, playing the chief part in digestive function of human oral cavity, and investigated the influences of mastication on the digestion of the starchy food.
Masticating test was made by the use of three types of the test food made from 2 g Japanese rice. At first, non-masticating test was made by putting the test food in the oral cavity only but not masticated. Then the 5-times-repeat masticating test was made. The author expressed the amount of total glucose produced and the reduced amount of the test food by means of the difference between the result of masticating and that of non-masticating tests.
Masticating test was done for 10 times, 20 times, 30 times and 60 times mastication as masticatory tempo (M. M.) =60 about each of three types of test food and was done at the hungry time before lunch.
After the complection of non-masticating and masticating tests, their substances were collected at the same time as the salivary amylolytic action was stopped. The following methods in which a fixed quantity of sugar was adjusted and the measurement of total glucose produced was done in accordance with Kobayashi's method.
Maltase solution which dissolves maltose into glucose perfectly was used in the density of 1, 000mg/dl and at pH in 4.0 for the same dose of sample. Incuvation was done for 30 minutes in 37°C.
According to the above purpose and methods, the amount of total glucose produced and the reduced amount of the test food were measured and investigated the variation in the amount of total glucose produced and the reduced amount of the test food being measured five times once a week in each subject, and the difference of the amount of total glucose produced by the 5-times-repeat masticating test.
The results obtained from the present investigations were as follows
1. As regards both the amount of total glucose produced of the reduced amount of the test food, there were observed variations in the results of measurements five times once a week and individual variations were recognized.
2. There was not observed any particular tendency in the times of test in the amount total glucose produced in case of the 5-times-repeat masticating test.
3. With the same type of test foods, the amount of total glucose produced increased in proportion to increase of masticating times.
4. The reduced amount of the test food increased in proportion to an increase of masticating times in each type of test foods.
5. The rise of the amount of total glucose produced and the reduced amount of the test food between 20 times and 30 times mastication was higher than the rest.

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There are many studies on the full cast crown, but the all-out dynamic studies foraxial, ocolusal and margunal form, that is very important factors, have not been find. The author tries to analyze the dynamic effect of differences of full cast crown abutment on the abutment, then the two-dimesnional photoelastic studies are carried out. The maxillar bicuspid for specimens is bucco-lingual synmetrical form, and the specimens being enlarged the three times of this teeth. are made by the B-hardner #901. The photoelastic apparatus, product of the Riken-keiki Co., is used for this study. The load direction is arranged at the long axis of specimen, the monochromatic fringe photographes are taken and analyzed.
The abutment forms of full cast crown consist of three factors, that is the axial angle (5, 10, 20 and 30 degrees), the cusp angle (0, 10, 20, 30 and 40 degrees) and the marginal form (knife edge type, chamfer edge type, bevel edge type, bevel-shoulder edge type and shoulder edge type), and are carried out to analyze by the two-dimensional photoelastic test. Futhermore, the specimens with the axial angle of 5 degrees the cusp angle of 30 degrees are preparated of three marginal forms (knife edge type, chamfer edge type and shoulder edge type) and they are analyzed. The dynamic effects of differences of abutment forms on the abutment are investigated and the following conclusions are obtained.
1. Regarding the axial angles, the each specimen with 5, 10, 20 and 30 degrees is researched. The maximum stress concentration in each specimen is observed at the pulp horn. Its value is tend to increase according as the axial angle increases. Therefore, it is concluded that theless the axial angle is, the more the abutment is dynamically. Consquently, the best axial angle is 5 degrees.
2. As regards the cusp angle, the each specimen with 0, 10, 20, 30 and 40 degrees is studies. The strees concentration is observed at the pulp horn and margin. It is find that the more the cusp angle increases, the less its values are. Then, the cusp angle is best according as it increase, especially, it is effect as to decrease the stress concentration at the pulp horn and margin.
3. As for the marginal forms, the specimens with knife edge type, chamfer edge type, bevel edge type, bevel-shoulder edge type and shoulder edge type are investigated. Regarding the stress concentration at the pulp horn, the knife edge type is minimum, and the chamfer edge type, bevel edge type, bevelshoulder edge type and shoulder edge type are increased in order of magnitude. Consquently, the knife edge type is best, the chamfer edge type, bevel edge type, bevel-shoulder edge type and shoulder edge type are in order of magnitude.
4. As regards the specimen with the axial angle of 5 degrees and the cusp angle of 30 degrees being preparated for the marginal forms of knife edge type, chamfer edge type and shoulder edge type, the knife edge type is best. The chamfer edge type and shoulder edge type is in order of stability. In case of the shoulder edge type with the cusp angle of 30 degrees, the stress of margin and pulp horn is remarkably decreased. As to use of this type, this is careful consideration.

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