The Morphology of the Primary Dental Arch in Shanghai, China : 72 Cases of Normal Occlusion

[Summary] To obtain the dimensional data of the dental casts of growing and developing Chinese children, and to compare the data to the Japanese, we have performed dental examinations on children in the kindergarten attached to Shanghai Teachers' University in Shanghai since 1996. As study materials, dental casts obtained between 1996 and 1999 from 72 Chinese children aged 3 to 6 years with normal primary occlusion were used to evaluate the mesio-distal crown diameters of the primary teeth, the sizes of the primary dental arch, and the standard values and frequency distributions of primary occlusion. 1. Males showed higher values in mesio-distal crown diameters in deciduous teeth, and the size of dental arch than females. 2. In regard to the interdental spaces both in the maxilla and mandible, primate and developmental spaces together were most frequently observed. 3. In regard to the occlusal relationship, the incidence of terminal planes was higher in the order of Vertical type > Mesial step type > Distal step type, and the incidence of primary canine occlusal relationship was higher in the order of type I > type III > type II. 4. The items that were thought to be characteristic of Chinese children were the frequency of only primate spaces, and the incidence of the Mesial step type of terminal plane and type III primary canine occlusal relationship.