Effect of dental prosthesis on the facial appearance of elderly patient (Development of a esthetic evaluation system)

为了解假体对老年患者面部外观的影响，进行了两种美容评价试验。全口义齿佩戴者的脸部用数码相机拍照。用图像处理程序对各种图像进行处理。20名牙医和20名牙科学生对这些图片进行了“自然”和“陈旧”的评分。实验一研究了不同牙合垂直尺寸(OVD)和不同唇舌位置对面部美观评价的影响。(1)牙合垂直尺寸小于-3 mm和大于-6 mm的变化使面部看起来更老。(2)人工前牙的唇舌位置在舌向移动2 mm或更多，使面部看起来不自然和老。(3)当咬合垂直方向移动2 mm时，在正侧面上看不到面部的衰老面部侧貌的美学评价会受到摄影角度的影响。实验2是为了确定全口义齿中线位置和切线倾斜度的美学可接受范围。(1)牙科学生的审美评价结果的差异大于牙科医生。(2)从自然外观的角度来看，中线偏差在±1.0 mm以内是可以接受的。(3)从自然外观的角度来看，切牙倾斜度在±1.5度以内是可以接受的。(4)从眼睛的中点开始画出的与义齿中线平行的假想线似乎是确定义齿中线的一个有用的指标。

In order to clarify the effect of prosthesis on the facial appearance of elderly patient, two kinds of esthetic evaluation tests were conducted. Faces of the complete denture wearers were photographed with a digital camera. The various images were processed with an image processing program. Twenty dentists and 20 dental students evaluated the images with "natural" and "old" appearance score.1. Test 1 was conducted to investigate the effects of different occlusal vertical dimensions (OVD) and labiolingual positions of article anterior teeth (LLP) on facial esthetic evaluation.(1) The changes of occlusal vertical dimensions of less than -3mm and more than 6 mm give the face an older appearance.(2) Displacement of the labiolingual position of artificial anterior teeth by 2mm or more in the lingual direction gives the face an unnatural and older appearance.(3) Displacement of the LLP by 2mm in the lingual direction does not confer an older appearance to the face in the frontal and lateral views when the occlusal vertical dimension is also increased.(4) Esthetic evaluation of the facial profile can be affected by the angle of photography.2. Test 2 was conducted to determine the esthetically acceptable range of deviation of the midline position and incisal inclination of complete dentures.(1) The variance in the results of esthetic evaluation was greater among dental students than among dentists.(2) Midline deviation within ±1.0mm is acceptable from the viewpoint of natural appearance.(3) Incisal inclination within ±1.5 degrees is acceptable from the viewpoint of natural appearance.(4) The imaginary line parallel to the denture midline drawn from the midpoint between the medial angles of the eyes seems be a useful indicator for determining the denture midline.