Iwasawa T, Moro T, Nakamura K
Am J Orthod. 1977 Aug;72(2):119-27. doi: 10.1016/0002-9416(77)90054-9.
A total of thirty-six Japanese adult subjects (consisting of eighteen men and eighteen women) with normal occlusion and harmonious facial features were subjected to cephalographic examination for the purpose of studying their soft tissues. Out of this group, twenty were selected and compared with twenty Class II, Division 1 and twenty Class III patients for the purpose of establishing an appropriate diagnostic guide for the Tweed triangle. These are our conclusions: 1. The Z angle of the Japanese subjects with normal occlusion was 69.70 degrees for the men and 71.75 degrees for the women. There is no significant difference between the sexes. 2. Although there are no significant differences between the sexes for the integumental and total chins, there is slight sexual difference for the upper lip measurement. 3. As compared to the subjects with normal occlusion, there is a significant difference for the Z angle of Class II, Division 1 and Class III patients. 4. In this study, the measurements of the Tweed triangle were FMA 27.28 degrees, IMPA 95.50 degrees, and FMIA 57.22 degrees. On the basis of this study and the reports of other Japanese investigators, we would like to suggest an FMIA of 57 degrees as being the most suitable basis for the diagnosis of Japanese patients, but this should be modified according to the FMA value.
共有三十六名咬合正常、面部特征协调的日本成年受试者（包括十八名男性和十八名女性）接受了头颅测量检查，以研究其软组织。在这组受试者中，挑选出二十名与二十名安氏II类1分类患者和二十名安氏III类患者进行比较，目的是为Tweed三角建立合适的诊断指南。我们的结论如下：1. 咬合正常的日本男性受试者的Z角为69.70度，女性为71.75度。两性之间无显著差异。2. 虽然两性在颏部皮肤和整个颏部方面无显著差异，但在上唇测量方面存在轻微的性别差异。3. 与咬合正常的受试者相比，安氏II类1分类和安氏III类患者的Z角存在显著差异。4. 在本研究中，Tweed三角的测量值为FMA 27.28度、IMPA 95.50度和FMIA 57.22度。基于本研究以及其他日本研究者的报告，我们建议将57度的FMIA作为诊断日本患者的最合适依据，但应根据FMA值进行调整。
