Abstract
Orthodontic diagnosis is the key factor for conducting a successful orthodontic treatment. It typically includes comparing a patient's cephalometric measurements to standard values. However, lateral cephalometric norms, may be specific to an ethnic group and cannot always be applied to other ethnic types. Thus the purpose of this study was to compare the cephalometric features of Class I malocclusion in Egyptian and Japanese adult females inorder to understand the ethnic differences between these two groups. The lateral cephalograms of 50 Egyptian adult females and 50 Japanese adult females were traced and digitized by one investigator. Seventeen angular measurements and thirteen linear measurements of facial form were computed. A comparison of the vertical dimensions showed that, the Japanese had a significantly steeper mandibular plane angle. Also, Japanese females had a significantly larger lower face height together with increased distances of the posterior teeth to the mandibular plane. For the soft tissue dimensions, the Japanese subjects had a significantly less prominent nose, protruded lip positions, and a more retruded chin compared with Egyptians. These characteristic skeletal and soft tissue different features should be taken into consideration when formulating an orthodontic treatment plan for patients of varying ethnic backgrounds to optimize the final results.