Karavaka Sofia M, Halazonetis Demetrios J, Spyropoulos Meropi N
Department of Orthodontics, University of Athens Dental School, Athens, Greece.
Am J Orthod Dentofacial Orthop. 2008 Feb;133(2):277-82. doi: 10.1016/j.ajodo.2006.02.037.
Clinical assessment of facial type and facial proportions is an important element of orthodontic diagnosis and subsequent treatment planning. Because of the subjective nature of this procedure, it is important to identify factors that could affect final judgment. One such factor that has been shown to affect facial perception in general might be the configural relationship of internal parts of the face. Our aim in this study was to assess whether configural changes in a face affect the subjective evaluation of facial type.
The frontal photographs of 2 white boys, aged 12 years, with harmonious face were used. The photographs were manipulated by computer to produce realistic images of faces with various configural relationships of the features. The modifications were interocular distance enlarged by 3 mm or reduced by 3.6 mm, mouth width enlarged by 4.5 mm or reduced by 4.2 mm, and mouth moved vertically upward or downward by 2.8 mm. Two images with a true change of the frontal facial height by 4 mm were also produced. The images were presented in pairs to 20 experienced orthodontists. Each judge evaluated 36 pairs of images (including pairs of identical images), all belonging to the same patient, in a random sequence. The judges were unaware of the changes that had been made to the photographs and were asked to evaluate which of the 2 faces appeared longer.
The judges correctly identified pairs of identical images with an accuracy of 42%. Reduction of the interocular distance and downward movement of the mouth caused the illusion of a longer face. The opposite changes had the reverse effect. Enlargement of the width of the mouth did not appear to influence the subjective impression of facial type, but reduction of mouth width had a statistically significant result, giving the impression of a longer face.
Configural relationships among the constituent features of a face can influence our judgment about external facial proportions. Because of the importance of these factors in treatment planning, clinical evaluation of faces should be accompanied by objective assessment (measurement) of photographs, so that any illusory visual effects can be identified.
面部类型和面部比例的临床评估是正畸诊断及后续治疗计划的重要组成部分。由于该过程具有主观性，识别可能影响最终判断的因素很重要。一般来说，已证明会影响面部感知的一个因素可能是面部内部各部分的构型关系。本研究的目的是评估面部的构型变化是否会影响对面部类型的主观评价。
使用了2名12岁白人男孩面部和谐的正面照片。通过计算机对照片进行处理，以生成具有各种特征构型关系的逼真面部图像。修改包括：两眼间距离扩大3毫米或缩小3.6毫米；嘴宽扩大4.5毫米或缩小4.2毫米；嘴垂直向上或向下移动2.8毫米。还制作了两张正面面部高度实际变化4毫米的图像。将这些图像成对展示给20名经验丰富的正畸医生。每位评判者以随机顺序评估36对图像（包括相同图像对），所有图像均属于同一名患者。评判者不知道照片所做的更改，并被要求评估两张脸中哪张看起来更长。
评判者正确识别相同图像对的准确率为42%。两眼间距离缩小和嘴向下移动会造成脸更长的错觉。相反的变化则产生相反的效果。嘴宽扩大似乎不影响对面部类型的主观印象，但嘴宽缩小有统计学意义的结果，给人脸更长的印象。
面部组成特征之间的构型关系会影响我们对外在面部比例的判断。由于这些因素在治疗计划中的重要性，对面部的临床评估应辅以对照片的客观评估（测量），以便识别任何虚幻的视觉效果。
