第一位萌出永久歯の変化に関連した顔面頭蓋計測値と乳歯の齲蝕状態

抄録

The relationship among the eruption order of the first permanent teeth, craniof acial measurements and caries of the deciduous teeth was examined, in order to investigate the factors relating to the changes in the eruption order of the first permanent teeth from the first permanent molar (M₁) to the central permanent incisor (I₁). Craniof acial measurement and dental observation were conducted on 462 preschool children. According to their first permanent teeth, the children were divided into two groups, the one contained the children whose first permanent tooth was mandibular Il (I-type children), and the other contained the children whose first permanent tooth was mandibular M1 (M-type children). Eighty-two boys and 67 girls were the I-type children, and 48 boys and 63 girls were the M-type children. The results of craniofacial measurement and dental caries of deciduous teeth were compared between the I-type and M-type children. Statistical analyses were performed by t-test and discriminant analysis. Results were as follows: 1) In both sexes, the mandible of the I-type children was smaller than that of the M-type children. This result suggests that the changes of the eruption order of the first permanent teeth are related to the involution of the mandible in man. 2) Dental caries were more prevailing in the M-type children. The result suggests that the increase of I-type children is related to the recently observed phenomenon of the decreasing dental caries in deciduous teeth. 3) Only in the girls, the I-type children's head-length were shorter than those of the M-type children. 4) As to physical characteristics, the I-type boys were fatter than the M-type boys, and the I-type girls were taller than the M-type girls.