As one of the approaches for improving the maternal and child health care system, it was attempted to review the dental part of the maternal and child health handbook. Our recommendations are as follows:
As a basic philosophy, all considerations regarding dental health should be on the same basis and at the same level as holistic health care. Therefore, the dental examination chart and the instructions for dental health care should be arranged in the same page as the general health examination and education at each stage of the physical and mental development.
It is strongly advised to pay attention to the development and underdevelopment of occlusion. It is essentially important to start the dental health examination program specially refered to the type and pathogenic factors of malocclusion as early as possible, so that the developmental changes of maticatory system can be well understood. For this purpose, new criteria for the occlusal examination of deciduous dentition are presented. In the dental health education, instructions for bringing up the morphologically and functionally sound, and traumaresistant masticatory system should be most important, including the informations on effects of breast feeding to the basic growth of the masticatory system, and on the influence of the physical properties of foods on its growth in and after weaning period.
The role of the maternal and child health handbook should be clearly defined as to record all the evidence through the developmental stages, as well as to motivate the mother and child complex towards the self care for health. The influences of mother's diseases and of the affecting stress caused by the treatment of these diseases should be mainly concerned about for fetus, rather than for the maternal body. Spaces must also be provided for recording the child's diseases and preventive care and treatment.
Eruption times of all deciduous teeth have better to be graphically illustrated for the mother to compare her own child's tooth eruption with. Code numbers may be advisable for the easy and accurate extract of the data, when necessary epidemiological investigation would be carried out.

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The purpose of this study was to analyze the factors inducing caries. These factors were analysed by using data from the surveys of the same children at the ages of 18 months and 3 years.
At the age of 18 months, caries-free children were classified as type O₂ by the presence of plaque and/or white spot enamel region, and others were classified as type O₁. In these two groups we analyzed on the relationship between caries incidence and three different backgrounds. These backgrounds were environmental, health and daily habit factors. We also analyzed the relationship between each daily habit factor and environmental factors. The results were as follows:
1. Both O₁ and O₂ type were analyzed in regard to environmental, health and daily habit factors by using Hayashi's Quantification Scaling Type 2 Method. The criterion variables were divided into 3 groups: a caries-free group, a group with caries of the anterior region only, and a group with caries of the posterior region. These were determined at the age of three.
2. Environmental and health factors had the discriminant principal components. The first one was characterized by the presence or absence of molar caries, and the second by the presence or absence of caries.
3. In the O₁ type, there were two discriminant principal components in the daily habits. The first one was regularity of daily life, which characterized the caries occurence of the anterior teeth only or of the molar caries. The second one was irregularity of daily habits during the period from 18 months to 3 years old, which characterized the presence or absence of dental caries at the age of three. The children with caries of the anterior teeth showed regularity of daily life and good conditions at home. On the other hand, the children with molar caries had no regularity of daily life and a poor environment at home. The caries-free group showed restriction or control of intake of sweets and habitual brushing by their mothers. The two caries-positive groups showed a tendency that was the opposite of the caries-free group.
In the O₂ type, parental care at the age of 18 months was the first discriminant principal component, which characterized the presence or absence of anterior teeth caries. The caries-free group showed good daily habits at the age of 18 months. The children with anterior teeth caries had poor habits. The second discriminant principal component was control of eating habits during the period from 18 months to 3 years, which characterized the presence or absence of molar caries. Caries-free children showed good eating habits during this period and brushed their own teeth more than twice a day at the age of three. Children with molar caries showed the opposite tendency at the age of three.
4. The Type 2 Method of Hayashi's Quantification Scaling was applied to the analyses on the relationship between each category of daily habits and environmental factors. Each category and change was used as the criterion variables. There were some problems regarding eating habits and contents of meal at the age of 18 months. At this time, the monthers' ages were between 21 to 27. There were some problems regarding stopping bottle feeding in the first or second child among the group of mothers who were over 31. There was some tendency toward prolonged bottle use, delayed toilet training, finger sucking, and beverage intake during the night in the families comprising three generations, where the mothers were over 31. Regional difference had the most influence on snack intake.

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The reduction of the masticatory organs in the process of human evolution is related to the changes in diet during development of the human culture.
The direct cause is considered to be related to the decrease of mastication consequent upon the softening of foods and concentration of nutritive substances by cooking and processing of food materials. This study was carried out to establish the standard for evaluating the amount of mastication for modern Japanese.
For evaluation of the amount and force of mastication, action potentials and their integrated values were recorded electromyographicaly in six young adults with normal occlusion.
As the result, the liquefied or gelatinous foods needed less mastication. Hard and fibrous foods needed much mastication. From the integrated values of the masseter muscles, foods were classified in to 7 groups according to the amount of mastication needed for a bite sized morsel. Using these values, unusual foods can be scored.

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This study investigated the relative effects of fluoride concentration in drinking water and daily habits on the dental caries of 4- and 5-year-old children living in 8 regions in the Tohoku, Kanto, Ko-shin-Estu and Hokuriku districts, who has received differing water fluoride levels for at least 7 years.
There were 20 water-supply systems in the 8 regions, and their fluoride concentration ranged from 0 to 1.4 ppm, which was confirmed by my own analysis.
In 1983, dental examinations were carried out by three dentists who had been trained to obtain reproducibility and objectivity of diagnosis, adopting the 'Blind Recording Method', whereby those three dentists had no information about the regions, such as the fluoride concentration in the drinking water. In addition, the information on the childrens' daily habits was obtained through a questionnaire to their parents.
Subjects chosen for analysis were 1078 4- and 5-year-old children who had lived in the regions since birth.
A significant negative correlation was found between mean dfs and the fluoride concentration in the drinking water.
An analysis of the factors which have an influence on the dfs number was also made by means of the 'quantification theory (1) ', that is a series of multivariate analyses, because caries is a disease with many causes.
A relative measure of the influece of a factor was provided by the magnitude of the absolute value of the partial correlation coefficient.
The partial correlation coefficient of the fluoride concentration in the drinking water was -0.259 (4-year-olds) and -0.298 (5-year-olds), and this was the highest coefficient (p<0.01) of all. That of regional factor was second (p<0.05), and the coefficients of the other factors were not significant.
'Quantification theory (1) ' made the inverse relationship between the caries prevalence of deciduous teeth and the fluoride concentration in the drinking water much clearer.
But the fluoride concentration in the drinking water was no longer the highest factor when the analysis of the 'quantification theory (1) ' was made after removing children receiving 1.1 ppmF and 1.4 ppmF (4-year-olds) or 0.6 ppmF and over (5-year-olds).
The findings confirmed observations that the caries prevalence of deciduous teeth varies inversely with the fluoride concentration in the drinking water, and suggested that the minimum concentration in the drinking water which was more influential for preventing caries of deciduous teeth than other factors such as regional factor and daily habits ranged from 0.6 to 1.1 ppm.

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We developed a new method for measuring and observing scattered dust with a laser beam. The method employs photographs and an He-Ne laser, which has the properties of directivity, high brightness, monochromaticity, and stability.
Dust was photographed as scattered light in the path of a laser beam that was scanned vertically or horizontally. We obtained the following results.
(1) The scattering of cutting dust could be observed accurately in three dimensions in photographs taken with the laser.
(a) Dust appeared as curling smoke during cutting of an artificial porcelain tooth or an extracted human tooth with a dental micromotor.
(b) Dust appeared as a cloud during cutting of an extracted human tooth with an air turbine.
(c) It could be seen that scattered dental dust was sucked up sufficiently and effectively with the local exhaust apparatus that we used.
(2) Our method is an effective means for various studies in industrial hygiene, such as those involving cutting work or local exhaust systems.

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