The dynamic impression material changes in its physical properties with the lapse of time after mixing. To make clear such changes, the author measured relaxation of the trially made dynamic impression materials with a relaxometer and examined their viscoelastic behaviors. The results will be given in the following : 1. There are two types of commercial dynamic impression material. In one of them, relaxation time is extented, while in the other, reduced with a rise in modulus of elasticity. 2. The effect of ethanol in the mixing liquid on the mixture of the trially made dynamic impression material is that it acts as an accelerator at the initial period of hardening and as a plasticizer at the subsequent period.

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A field was conducted on tooth caries prevalence and rates of treated cases on the population groups of middle and high school students residing in Kitakyushu city and a suburban community, Wakamiya-machi, Kurate county. Figures obtained were analyzed for age, sex and regional groups, and the results were summarized as follows. 1. DMFT Index (FDI) The indexes increased with advancing age in all subjects regardless of sex and rigional differences. Comparison between both sexes groups showed that the female groups had greatwer indexes that the male groups in both districts, and comparison between both district shoed that the indexes were greater in the male subjects of the urban community and in the female subjects of the suburban community than in the respective control groups. 2. DMFT Rates Rates of DMFT increased in all subjects regardless of sex and regional differences with advancing age, although but slightly. The rates for the female subjects exceeded those for the male in both districts, but those for the male subjects were greater in the city than in the suburban community, and those for the female subjects were vice versa. 3. FT rate (rate of treated among decayed teeth) FT rates increased in both sexes groups of both districts with advancing age. The female subjects showed greater rates than the male subjects in both districts, and the city groups showed greater rates than the suburban groups regardless of sex difference. 4. DMFT rates for individual teeth Rates of DMFT showed a wide variation among individual teeth of the mouth, and an equally marked variation existed among the same named teeth on upper and lower quadrants.

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The results of some studies on AKM (Aminodeoxykanamycin) were summarized as follows : 1. Antibacterial activity of AKM on different samples of pathological materials, collected in our clinic was determined by paper disc method. In comparison with other antibiotics, AKM exhibited the highest antibacterial activity as well as Kanamycin against Staphylococcus aureus, Streptococcus and Corynebacterium. 2. 44 strains of pathogenic Staphlylococcus aureus tested were inhibited in M. I. C. of 0.78∿50mcg/ml. 3. The blood levels of intramuscularly administrated AKM (200mg/body) were calculated as 5.2∿7.2mcg/ml after 30 minutes, 0.7mcg/ml even 13 hours later. 4. The results of the clinical use of AKM showed excellent in 7 of 20 cases, good in 9 and poor in 4. No side effect was observed.

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1. The speech aid appliances were administered to 13 patients out of a total of 26, all of whom showed symptoms of speech defect after being operated for the cleft palate, and the remaining 13 patients were left without treatment to serve as control. Comparison was made on how many months did it take for each patient of treated group and non-treated group to succeed in passing the monosyllable intelligibility test. The results showed that the patients of treated group took in the average 6.5 months and the patients of non-treated group 11.8 months to attain the goal. 2. The speech aid appliances were administered to 4 patients with speech defects, of whom one had the submucous cleft palate and uvula bifida, two had the soft palate insufficiency and the remaining one had the mouth unsuccessfully operated for cleft palate. Measurement was conducted on these patients for their nasal emission using respectively the spirometer, the vinyl ball of 30 cm diameter and the straw tube. The application of the speech aids on these patients proved to be greatly beneficial in improving their nasal emission, intelligibility of speech and in reducing the nasal voice.

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The purpose of the present paper was to compare the electrical activity of the left with the right masseter muscle on subjects who had not any complaint related to occlusion. The authors examined 127 subjects from eighteen to forty-six years of age. The subjects were selected on condition of having neither denture nor pain in the teeth during the clench in centric occlusion. Bilateral electromyograms were recorded simultaneously from the left and right masseter muscles during the clench in centric occlusion by surface electrodes. The results were as follows : 1. Many cases revealed obvious difference in amplitude of discharges elicited from both masseter muscles during the clench in centric occlusion. 2. In almost all the cases, the difference in amplitude of discharges elicited from both masseter muscles during the clench in centric occlusion remained constant in the lapse of time. 3. In many cases, the side which generated dominant discharge during the clench in centric occlusion coincided with the habitual masticatory side. 4. a) On the subjects indicated no difference in amplitude of the discharges elicited from both masseter muscles during the clench in centric occlusion, the discharge elicited from the masseter muscle on the clenched side was greater than that on the other side during the clench on one side. b) On the subjects indicated difference in amplitude of discharges elicited from both masseter muscles during the clench in centric occlusion, dominant discharges were elicited from both masseter muscles by clenching the side which elicited small discharge during the clench in centric occlusion. The discharge from masseter muscle of the clenched side was greater than that of the other side during clenching of the side which elicited dominant discharge by the clench in centric occlusion.

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