In the previous report, it was pointed out that the Okamoto's original histochemical method for tin was not applicable to enamel owing to its strong acidity.
Therefore, the purpose of this experiment was to improve the original procedure in order to establish the reliable histochemical method for tin in dental enamel.
The first experiment was concerned with the spectroscopic observation on the tin-gallein complex. The tin-gallein ethanol solution showed a strong absorption at 500mμ, while no distinct absorption was found in the range of visible light with the gallein ethanol solution alone. Thus, the differentiation between both was very easy.
On the contrary, the original acidic galleinethanol solution itself had a strong absorption at 460 mμ, which resembled that of the gallein-tin complex at 480 mμ. The contrast between these two colors was too weak to distinguish each other. The advantage of the gallein-ethanol solution was thus clearly demonstrated.
In the application of the staining, freshly extracted teeth were first treated with stanuous fluoride. After stained by the gallein ethanol solution, thin ground sections were made of them and observed under the microscope. The characteristic findings on ground sections were that the artificially decalcified lesions such as disussed in the previous report were never found at any potion. The red spots representing gallein-tin complex were clearly distinguishable from the other portions of enamel structure.
The procedure for the improved histochemical method was: stain the tooth or tooth section in 0.1% gallein ethanol solution at 37°C (optional) for 5 days or more.
From the results mentioned-above, the improved gallein method will serve for the histochemical observation of tin in or on enamel to elucidate the mode of action of stannous fluoride in preventing dental caries.

View full abstract

The relationship between the dental caries and the physical constitution together with the incidence of absence to school, which might be connected with learning, was investigated by making use of individual records of both physical and dental states at the time of the periodical health examination in 1963 on 259 pupils, the second- to the 6th-year graded, of a certain elementary school at a central part of Tokyo City.
As for the classification of caries proceeding grades, deciduous teeth and permanent teeth were separately divided into either the treatment teeth or the carious teeth. In particular, carious teeth among permanent teeth were subdivided into the dental caries of the first grade (C₁), of the second grade (C₂), of the third grade (C₃) and of the fourth grade (C₄). Concerning to each grade, the average number of carious teeth per person was calculated and checked in relation to the physical constitution such as the height, the weight and the girth of the chest and to the incidence of absence to school, obtaining the following results.
1. In the height, as compared with those who showed higher values than the national average value, those who showed lower values had more carious teeth. In deciduous teeth, the number of carious teeth was larger equally in pupils of all the year grades, while in permanent teeth the number of carious teeth of C₂ and C₃ was larger in them except for the 5th year grade.
2. In the weight, those pupils who showed lower values than the national value of average, as compared with those who showed higher values, had more carious teeth in deciduous teeth throughout the year grades. Meanwhile, in case of their permanent teeth, the number of treatment teeth were smaller in the 2nd, 4th and 6th year grades. However, the 6th-year graded pupils showed a little larger number of C₂, C₃ and C₄ carious teeth.
3. In the girth of the chest, those pupils who showed lower values than the national average value, when they were compared with those who showed higher values, had generally more carious teeth in deciduous teeth throughout the year grades. In permanent teeth they exhibited a small number of treatment teeth except for pupils of the 3rd year grade. At the same time, it may be said that C₁ was rare except for the 5th-year graded pupils, while C₂, C₃ and C₄ occurred in general frequently.
4. As described above, it was observed that carious teeth appeared rather often in case of the poor physical constitution at the time of the examination, that means, in pupils showing a poor bodily development, suggesting the importance in the protection of deciduous teeth during the elementary school period.
5. During one year before the physical examination, those pupils who were never absent to school showed, in comparison with those who made as many as more than 10 times of absence, more numerous carious teeth of deciduous teeth in the 2nd, 3rd and 4th year grades and C₁, C₂ and C₃ of permanent teeth in the 5th and 6th year grades. Therefore, it is assumed that the absence to school may be connected with the caries of the deciduous tooth in pupils of the low and middle year grades and of the permanent tooth in those of the high year grade.
6. Similarly, if the R.I.D. Index (1961) of pupils making no absence was compared with that of pupils showing many times of absence, the former exhibited lower values throughout the year grades. Consequently, those who showed high caries proceeding grades of both deciduous and permanent teeth, showed also frequent absence to school.

View full abstract

A total of 487 pupils ranging from 4 to 6 years of age, selected from 5 kindergarten in Tokyo City were investigated. Dental examination was conducted together with the nutrition investigation based on the Nutrition Survey in Japan. The investigation was conducted for three days from October 2, 1963.
As for the nutrition, the amount taken was investigated for each item of investigation. As for the teeth, the number of caries was compared and observed for each kindergarten and each age group. The results were as follows.
1. In case of the total number of boys and girls, the carious teeth prevalence rate was 88% for 4 year old children, and 96% for 5 and 6 year old children. When these figures were compared with the national average shown in the Report of the Survey of Dental Diseases (1957) conducted by the Medical Affairs Bureau, Ministry of Health and Welfare, the number was low for 4 year old children, high for 5 year old children, and the same for 6 year old children. As for the average number of carious teeth per person, it was 5.4 for 4 year old pupils, 8.1 for 5 year old pupils, and 8.1 for 6 year old pupils. They were all less than the national average.
2. As for 5 and 6 year old children, when the average number of carious teeth and the amount of the nutrition investigation items taken by each pupil were compared for each kindergarten and age group, the number of caries increased when the amount of candy taken was increased, and those taking sufficient amount of nutrition for all items of the investigation showed less caries.
In case the average number of carious teeth is obtained for the 3, 5, and 6 year old pupils according to the month of birth, those born in August and September had the greatest number of carious teeth. Contrary to this, those born in January and June had less number of carious teeth.
3. The difference in this average number of carious teeth per person was assumed to be caused by the changes in the mother body owing to climatic changes and especially the nutrition, since infants born in August and September have the period of mineralization in the bad season of summer when it is high temperature and high humidity whereas, infants born in January and June have the period of mineralization in spring or autumn when the climate is very good.

View full abstract