Analysis of cephalometric indices which are consistent with subjective evaluation for facial asymmetry.

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The purpose of this study was to investigate the relationship between the subjective evaluation of facial asymmetry and cephalometric indices. Ten orthodontists subjectively evaluated the frontal photographs of 100 subjects and categorized them into three categories, ie, category I, symmetrical view ; category II, a little asymmetry not requiring treatment ; and category III, marked asymmetry requiring treatment. Seven indices on the frontal cephalographs were obtained and compared between the categories in order to define the characteristics of each category. No differences were found in any of the indices between categories I and II. Five indices showed differences between category III and the other categories. Among them, the distance of Me from the vertical reference line was the most relevant index for the subjective evaluation of facial asymmetry. When a discrepancy is found between skeletal measurements and a subjective evaluation, the influence of soft tissue structures should … More be considered in facial asymmetry.Next, we tried to determine the threshold of cephalometric indices, by which orthodontists subjectively differentiated patients requiring treatment for facial asymmetry (Group B) from those who did not (Group A) on the frontal photographs of 100 subjects. The frontal cephalographs of these 100 subjects were also analyzed for 5 indices. For each orthodontist, the threshold was determined by means of the discriminant analysis. As the number of subjects, who were judged to require treatment, increased, the threshold of cephalometric indices became small and the discriminant accuracy was reduced. Among the 5 indices evaluated, the distance of Me (mean : 4.28 mm) or maxillo-mandibular midline angle (mean : 4.31 degree), which were the indices related to the Me, showed the highest accuracy in all observers. The distance of the Me and the maxillo-mandibular midline angle appeared to be the most relevant indices for subjective evaluation of facial asymmetry and the threshold determined in the present study has the potential to contribute to the planning and evaluation of orthodontic treatments. Less