Abstract
The purpose of our study was to establish the methods of conducting dental health surveys on 1Y6M old children, to find systemic oral diseases and to prevent dental caries. The subjects were the children 1Y6M to 3Y6M old children at 9locatities in Japan (Iwamizawa, Morioka, Sendai, Tokyo, Yokosuka, Ibaragi, Tokushima, Hiroshima, Fukuoka), and every 6 months were examined with respcet to their oral condition and habitat factora.
The eruption of deciduous teeth was related to the development of mastication and occlusion, and important for the prevent dental caries. In this report, the eruption of deciduous teeth were examined.
The results were as follows;
Rate of the eruption of deciduous teeth
At 1Y6M old most deciduous incisors were erupted, and the rate of eruption of the deciduous cuspid was 78.46% in the upper jaws and 66.65% in the lower jaws. The rate of eruption of the 1st deciduous molar was 94.50% in the upper jaws and 88.69% in the lower jaws at 1Y6M of age. And the rate of eruption of the upper 2nd deciduous molar was 14.38% at 2Y0M of age and 67.28% at 2Y6M of age, but the rate of eruption of the lower 2nd deciduous molar was 36.43% at 2Y0M of age and 88.93% at 2Y6M of age. At every age period, concerning the rate of eruption of deciduous teeth the left sides showed a somewhat higher rate than the right sides by compariosn, and boys showed a somewhat higher rate than girls. In the rate of eruption of deciduous teeth the upper 1st molar showed a higher rate than the lower jaws, but the lower 2nd molar showed a higher rate than the upper jaws. As for compariosons, between local areas in the rate of eruption of deciduous teeth at Iwamizawa and Yokosuka was higher than other, and the rate of eruption of deciduous teeth at Ibaragi was lower than in the other areas.
