We investigated the development (calcification) stages of the permanent anterior teeth of Japanese children by classifying them into 13 stages by the criterion of Moorrees, et al., using 11,167 panoramic radiographs, 5,759 of boys and 5,408 of girls, between the ages of 2 years 0 months and 14 years 11 months. The following information was obtained.
1) The development of the anterior teeth was earlier in girls than in boys at every stage. This was particularly true during the middle phases of development.
2) An anterior tooth on one side developed at the same rate as its counterpart on the other side, regardless of differences in sex or arch.
3) In both boys and girls, the development of a mandibular central or lateral incisor was earlier than that of the corresponding maxillary tooth. However, no difference was seen in the development of the canines.
4) When the development of each permanent anterior tooth was compared for Caucasians and Japanese:
a) The developmental age for the central and lateral incisors was considerably later in Japanese than in Caucasians.
b) Although the developmental age for the canine was earlier in Caucasians for the completion of the crown and other early stages of development, it was earlier in Japanese from formation of 2/3 of the root to apical closure.
c) When the developmental periods for each of the permanent anterior teeth were compared with the results of Nolla, Moorrees, et al., and Haavikko, the developmental periods for the central and lateral incisors were longer in Japanese, while those for the canines were shorter.
5) Standardized charts for the development of the permanent anterior teeth in Japanese children were constructed.
Using the above results, we can better understand the developmental age of the permanent anterior teeth of Japanese children. This provides us with new charts which are an improvement over the charts in current use which are for the teeth of Western children. This information can be put to immediate use in clinical practice.
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