CHANGES IN THE CARIES OF THE TEETH FOR INFANTS IN THE WARD DISTRICT OF TOKYO CITY

Abstract

Within the period of twelve years from 1948 to 1959, mass dental examination was performed on a total of 14, 194 infants residing in the Ward District of Tokyo City. When the conditions for successive years were observed, the following results were obtained.
The caries of deciduous teeth were expressed by the total of def., in other words, the total of caries of deciduous teeth, teeth requiring extraction and filled teeth.
1. When the percentage of persons who have experienced def and the average number of def teeth per person are observed in accordance with age and year, the figures for each age group are extremely small in the year 1948.
Furthermore, there is a tendency of the percentage of the caries of teeth increasing for each age group with every passing year.
This tendency is greater for the average number of def per person than for the percentage of the persons who have experienced def
2. When the totals of the figures for the percentage of persons who have experienced def and the average number of def per person are taken for each age group on an annual basis, and the average of the respective years is taken, although there are a few exceptions, the following tendency can be observed.
As for the percentage of persons who have experienced def in 1948 the percentage was in the thirties, from 1949 to 1959 in the fifties, especially in the period from 1958 to 1959 the percentage was an extremely high value of almost 60.
As for the average number of def per person, in 1948, between 1 and 2, in 1949 between 2 and 3, in the period from 1950 to 1953 between 3 and 4, in the period from 1954 to 1957 between 4 and 5, in 1958 and 1959 between 5 and 6, and all showed a tendency of increase with every passing year.
3. Next, the average number of def per person of the annual def which showed a tendency of extreme increase weee taken and observed from the age group point of view.
The results were as follows:
Each age group showed a tremendous rise in the period from 1948 to 1949, and infants from 2 years to 5 years of are showed a tendency of the average number of def increasing with age. However, those who belong to the 1 year old age group show a decreasing tendency with every passing year.
Those belonging to the three-year-old age group began to show a tremendous increase recently, that is, from around 1957.
4. When we compared on the annual basis the average number of def per person for infants belonging to the one-year-old age group and the types of nutrition taken by the infants residing in the Ward District of Tokyo (based on the investigation made by the Tokyo City Authorities) we found that there was an inverse correlation between the average number of d. e. f. per person and the rate of the bottle fed infants and children.
5. As for the average number of def per person, recently, we conducted the following investigation on the infants belonging to the three-year-old age group which showed a gradual increase in the number of def per person.
The def were divided into five layers from a morphological point of view and observed. It was found that there was an increase in def in all layers.
6. From the above observations, the annual changes in the def of infants and children residing in Tokyo City, and a few points associated with them were made clear.