A Comparative Study on Sinodont and Sundadont of Japanese Teeth

日本牙齿Sinodont与Sundadont的比较研究

• 批准号: 09671880
• 负责人: HANAMURA Hajime
• 金额: $ 1.47万
• 依托单位: Aichi-Gakuin University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09671880/
• 关键词: Sinodont; Sundadont; Lower first molar(MィイD21ィエD2; Distal root; Root canal; Upper incisor; Shovel; 上顎中切歯; 歯の形質; 歯の大きさと形質

It is the present situation that Sinodont and Sundadont, the two descends of Japanese group, must be considered when we conduct the comparative examination of the size and shape in Japanese teeth. This time we direct our attention to the number of the distal root canal in MィイD21ィエD2. By dividing the whole group into 1-root-canal group and 2-root-canal group, we investigate whether there are any differences between these groups in the odontometrical aspect. The aim of this research is to obtain the fundamental materials by which the Japanese group is classified into Sinodont and Sundadont in the aspect of dental morphology.(1) For Japanese male, the differences of the crown width In I2 and C' between the 1-root-canal group and the 2-root-canal group are significant, while the differences of the crown thickness in PィイD11ィエD1, PィイD12ィエD1 and IィイD21ィエD2 between these groups are significant.(2) For Japanese female, differences of all kinds of teeth between the 1-root-canal group and the 2-root-group are not significant.(3) For the 2-root-canal group, the sexual differences of the crown width in the lower canines are significant, while the sexual differences of the crown thickness in I1, IィイD22ィエD2, C, P1, MィイD12ィエD1 are also significant. Consequently, the sexual differences of the crown thickness are more than those of the crown width.(4) For the 1-root-canal group, the sexual differences of the crown width in I1, I2, C are significant, while the sexual differences of the crown thickness in C and M2 are also significant.(5) The appearance rate of Shovel-shaped incisor in the upper incisor of the 2-root-canal group is higher than that of the 1-root-canal group.

在对日本人牙齿的大小和形状进行比较研究时，必须考虑日本人的两个后裔Sinodont和Sundadont的现状。这一次，我们将注意力集中在MィイD21ィエD2的远端根管数量上。通过将整个根管分为1根管组和2根管组，观察两组在牙体测量学方面是否存在差异。(1)日本男性1根管组与2根管组I2、C‘牙冠宽度差异显著，PィイD11ィエD 1、PィイD12ィエD 1、IィイD21ィエD2组牙冠厚度差异显著。(2)日本女性，1-根管组与2-根管组牙冠宽度性别差异不显著，I1、I-ィイD22、ィエ-D2、C、P1、M-ィイ-D12-ィエ-D1牙冠厚度性别差异显著。1根管组I1、I2、C牙冠宽度性别差异显著，C、M2牙冠厚度性别差异显著。(5)2根管组上中切牙铲形牙出现率高于1根管组。

项目成果

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