This report describes the relationship between tooth decay and between-meal eatings taken by an infant. One hundred and fiftyfive subjects were examined, 84 two year-olds and 71 three year-olds. These infants live in their respective homes and visited the Tokyo Lion Dental Center due to some dental problems. The results of examination are as follows:
1. Nutritional elements taken in the form of between-meal eatings were predominately carbohydrates from the point of view of calories obtained from pastries.
2. Those who took, in the from of between-meal eatings, food consisting mainly of refind carbohydrate tended to have a high incidence of caries. The correlation coefficient between the two was 0.29 in 2 year-olds and 0.45 in 3 year-olds, and each coefficient was statistically significant at the 1 per cent level.
3. No correlation was found between the intake of milk and fruits containing no refined carbohydrate and the rate of caries experienced in teeth.
4. The intake of between-meal eatings involve many problems from the dietary standpoint. Guidance in between-meal eatings of infants in needed, since mothers of kindergarten pupils selected for comparison are little interested in the problem of between-meal eating.

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The widespread tendency of periodontal diseases shows markedly high occurrence rate in accordance with the increase of dental caries. There are complex causes of periodontal diseases. It is, however, the most important matter for the prevention of the diseases to practice mouth cleaning daily by the use of toothbrush and dentifrices. Such being the case, an attempt has been made on a comparative study of 3 additive drugs, to dentifrices, which are effective for the prevention of tooth surface-deposits as well as treatment of periodontal diseases.
As the materials and the method the present studies, healthy adults females were selected and 21 of them were instructed to brush their teeth with dentifrices containing Allantoin, while 24 of them with Ipsilon, and 25 with Dihydrocholesterol, during the period of 28 days, every day continuously.
And medical examinations on periodontal tissues were performed on the day immediately after using dentifrices, and thereafter every 7 days 5 times. Objective symptoms were checked by the use of index used for epidemic research related to periodontal diseases at the time of each medical examination.
On the other hand, subjective symptoms were observed on the cards of questionaires by instructing to write the symptoms. As the results, following featured effects were observed, that is, Dihydrocholesterine was proved to be effective for the removal of tooth-deposits or bad breath and disappearance of tooth-mobility, Ipsilon was proved to be effective for the relief of inflammation of gingiva, also, neither one of the above drugs in dentifrices showed particularly significant differences on the feeling to decreas swelling on gingiva and for hemostasis of hemorrhage from gingiva. Thus, either of the above drugs proved to be effective, although there are some difference of effects on each drug, as additives to the dentrifrices for the prevention periodontal diseases, in view of the reduction-rate on subjective and objective symptoms.

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To use massage cream effective on periodontal diseases and to massage gingiva as daily preventive means for periodontal diseases is a simple but effective measure by giving the idea for the prevention and treatment of periodontal diseases.
In order to prove this fact, studies were made by the use of Hinokitiol massage cream.
As the materials, adult female 27 patients were employed, they were suffering from periodontal diseases.
And they were instructed to make massage on gingiva at the frontal part of the teeth with fingers by the use of Hinokitiol massage cream everyday, morning and evening, for 36 days continuously.
As for observation methods, objective symptoms were observed on the index related to epidemic research of periodontal diseases, while, subjective symptoms were observed by checking questionaires, also pathological tests were combinedly performed.
As the result of comparing objective symptoms after making massage, marked reduction of index was observed after massaging than before. In calculating the reducing rate, the following order was observed from its high rate to low; OH I followed by bacterial plaque score, PIA index and Periodontal index. And also, subjective symptoms were decreased after making massage than before, proving the following order on the reduction rate; bad breath, swelling, bleeding from gingiva and teeth mobility.
While subjective symptoms proved the following order of reducing rate; bad breath, swelling, bleeding from gingiva and tooth mobility. As for pathological findings, the finding under the gingiva attached epithel was more improved after making massage than before. In conclusion, the progress of subjective and objective symptoms proved that continuous use of the above cream was very effective in the progress of treatment for more than 28 days.

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For the purpose to elucidate the nutritional essentiality or non-essentiality of minute fluoride and also the magnitude of the placental and mammary barrier for fluoride, the experiments of feeding rats defluoridated feed and fluoride water of graded dose through three generations were conducted.
1. The determination of minute fluoride was done with the latest device, the fluoride ion electrode. It was found to be very quick and reliable.
2. The basal diet contained 0.45ppm F which was as low as one hundredth of commercial rat compressed feed. The graded doses of fluoride water were 0, 0.5, 1, 10 and 50ppm.
3. The growth was retarded at 50ppm in both generations and at 10ppm in males of the second generation.
4. No significant difference was found in blood examinations between the dose levels, including erythrocytes and leucocytes count, hematocrit, ALP and GOT.
5. The adult male rats of the first generation of low fluoride feeding contained 14.1ppm F in femurs and 15.1ppm F in incisors, decreasing to only three per cent and nine per cent resp. of that on commercial rat compressed feed.
6. The adult male rats of the second generation showed no significant decrease of hard tissue fluoride compared with that of the first generation. It may be attributed to the accumulation from not so completely defluoridated feed through the growth.
7. The mandible of weanlings of the second generation contained fluoride as low as 8.7 ppm F. equivalent to 40 per cent of the mother rats.
8. The mandible of weanlings of the third generation contained 7.5ppm F, equivalent to 50 erpcent of the dams.
9. At all dose levels through 0, 0.5, to 1ppm of fluoride, the bones of weanlings were keeping a constant level of fluoride around 10ppm, indicating an active physiological barrier in placenta and mammary glands.
10. At 10 and 50ppm of dose level, the reduction of fluoride in hard tissues of weanlings showed a constant ratio around 10 per cent of that of dams, suggesting a passive physicochemical filtration. The absolute level in tissues of pups was consequently increased.
11. At higher dose level, the pups of the second generation contained significantly higher fluoride in hard tisses compared with that of the first generation.

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Carious cavities induced in fissures of 1106 Wister strain rats, from 41 groups belonging to 13 experimental projects, were recorded in respect to the prevalence (P) of caries in a group of rats, and the average extent (E) in each rat, and statistically analysed, resulting in the equation; P=0.502 log₁₀E+0.426. This result was introduced from a differential equation based on the fact that the susceptibility differences in any two successive orders go in inverse proportion to the susceptibility order of the site. The above functional relation can be adapted for a similar treatment of human caries, i. e., P_j=0.677 log₁₀E_j+0.495 for school children aged from 7 to 12 years. Due to the nature and ubiquity of this equation, it was considered that each result obtained on the prevalence and extent of rat caries must be corrected by it, and then the project should be discussed with these corrected values. The results of the correction indicated that a modification of the cariogenic-purified-diet (6PMV) by varying the vitamin B₁ content, substitution of casein for gelatin in 6PMV, post-eruptive administration of fluoride, and modification of the calcium-phosphorous ratio to a value of 2.0 had a caries inhibiting effect offsetting cariogenicity of this diet. Here inhibition by fluoride was concluded to be based on the statistical significance of the difference between two prevalences to be compared. Inhibiting effects of vitamin B1 and gelatin were concluded depending on the mode of action when an increasing amount lineally decreased prevalence as well as the logarithmic value of extent. Correction of obtained results and consideration of the mode of action of each agent will be a starting base for biological standardization. Another benefit in the correction of obtained results is that even if the scoring unit is changed it never causes an inverse effect. In the statistical treatment, the significance of the difference of the results have validity only when prevalences (P) are compared in the range less than 1, and the average logarithmic extents (E) of two groups are compared in the range P=1.

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