AN OBSERVATION MADE ON THE DENTAL EXAMINATION OF THREE YEAR OLD INFANTS RESIDING IN TOKYO CITY IN 1962

Abstract

In the fiscal year of year 1962, that is, during the period from April, 1962 to March, 1963, health guidance of three year old infants was made under the Juvenile Welfare Law at all of the health centers in Tokyo City. At that time health guidance charts were filled out, and among these charts, 61, 333 complete charts were selected as the object of study. When the annual average of the infants having dental diseases and the occuring conditions were observed, the following results were obtained.1. As for the dental caries, the percentage of infants affected was 67.9%. In case the contents are classified as, A Type: Infants having dental caries in the upper jaw front teeth only or upper and lower jaw molar teeth only. B Type: Infants having dental caries in upper and lower jaw molar teeth and upper jaw front teeth. C Type: Infants having dental caries in both the upper and lower jaw front teeth and the upper and lower jaw molar teeth, there were 48.0% of Type A, 38.2% of Type B, and 12.8% of Type C. Furthermore, the average number of teeth affected by caries per infant was 3.3.2. As for the malocclusion, the percentage of occurrence was 3.0%. If the contents are classified into a. Progenie b. upper protrusion c. open bite d. crowding e. diasthema, the respective percentage was as follows:a. 66.5% b. 13.4% c. 9.4% d. 5.7% and e. 5.3%3. As for the soft tissue disease of oral cavity, the percentage of infants affected with it was 1.4%. If the local ones are expressed as L type, and the system ones are expressed as the S type, the percentage of the L type was 86.5% and the S type 13.5%.4. As for other extraordinary conditions, the occurrence percentage was 0.4%.5. If each of the above figures are compared with the national average, although the occurrence rate of malocclusion and other extraordinary conditions were rather low, the soft tissue diseases of oral cavity were slightly high.6. Of all the health centers in Tokyo City, 27.391 health guidance charts were obtained from the health centers which conducted examination on infants which reached three year of age in the month preceding the examination month. When similar observations were made on these data classified by the month of birth, the following results were obtained.1) As for the number of infants affected with dental diseases and the annual average of occurrence, similar results to those of all health centers were obtained.2) As for the number of infants affected with dental caries, since the number of births in April, May, September, and October were great, they showed high percentage, and for infants born in June and July, the percentage was very low.3) As for the occurrence rate of malocclusion, the rate was high for the infants born in March and September, and low for those born in December and February. As for the contents, the majority was held by a. A large number of the infants affected by a, were born in August. Contrary to this, those born in January showed a low rate.4) As for the infants affected by the soft tissue diseases of the oral cavity, those born in May showed a high percentage, and those born in September showed a low percentage.5) As for the other extraordinary conditions, the results were similar to those affected by dental caries.6) By the observations made on the infants classified by the month of birth as described above, the percentage of three year old infants affected by dental diseases and the rate of occurrence was presumed to be closely related with the characteristics of the Japanese climatical environment which is high temperature high humidity in summer, and low temperature low humidity in winter, causing the nutritional condition of the mother to become bad when the said three year old infant is still in an embryonic stage.