This study investigated the mesio-distal crown diameters of the primary teeth, primary dental arches, standard values and frequency distribution of primary occlusion in Chinese children (residents of Shanghai). With the cooperation of a kindergarten in Shanghai, China, dental plasters were collected from 43 children (ages ranging from 3-6 years old) with normal primary occlusion. Based on the method reported by the Japanese Society of Pediatric Dentistry, the data were statistically analyzed and compared to those of Japanese children. The results are summarized as follows:
1. The mesio-distal crown diameters of the primary teeth did not differ between Japanese children and those from Shanghai.
2. Compared with the Japanese children, the children from Shanghai tented to show a shorter primary dental archlength.
3. Inter dental spaces of the primary dental arch did not differ among the Japanese children and those of Shanghai.
4. The frequency of the terminal plane relationship to the mesial-step type and the primary canines occlusal relationship to type III was significantly higher in the children from Shanghai than in the Japanese children.