Changes of facial actions in speaking and smiling by the dental treatment.

牙科治疗的目的之一是使嘴唇保持良好的平衡。前牙的位置与嘴唇的运动和周围环境密切相关。例如，上颌牙齿突出的受试者，即使上唇松弛，闭合时也需要强烈的上唇张力。下颌牙突出也不同于正常和上颌牙突出受试者。然而，面部表情的治疗效果很难确定。首先，我们引入了一个精确高效的三维测量系统，使用两台高速摄像机来分析面部表情。通过跟踪面部的6个标记来分析面部动作。结果如下：“Chi”的微笑与自然的微笑几乎相似，自然的微笑表现出一些变化的特征模式。另一方面，强迫微笑与其他两种微笑表现出不同的模式。没有情感，微笑的面部表情有些困难。因此，我们认为chi-smile除了自然微笑之外，还可以用于面部表情的研究。由于正常咬合的前牙上蜡的方法与前牙的面部动作的关系，结果表明，前牙的位置对嘴唇和周围环境的运动有很大的影响。我们还介绍了一个面部动作的三维显示程序。该可视化系统将为牙医和患者之间提供一个沟通工具。

One of the purposes of dental treatments is achieving a well-balanced surroundings of lips. A position of anterior teeth is closely related to the movement of lips and the surroundings. For example,in case of subjects with maxillary teeth protrusion, strong tension of upper lip is necessary for closing even if it is loose in relax. Mandibular teeth protrusion is also different from normal and maxillary teeth protrusion subjects. However, it is quite difficult to determine the treatment results regarding facial expression. The first, we introduced a precise and efficient three-dimensional measurement system using two high speed cameras to analyze facial expression. Facial actions were analyzed by tracking 6 markers on the face. Results were as follows.'Chi'-smile was almost similar to natural smile which showed a characteristic patterns with some variations. On the other hand, forced smile showed different patterns from the other two smiles. Facial expression of smile is somewhat difficult without emotion. Therefore, it is considered that chi-smile in addition to natural smile can be used in studies of facial expressions.As the relationship between overjet of anterior teeth and a facial action by method of setting wax on anterior teeth of normal occlusion, the results suggested, that a position of anterior teeth strongly influenced the movement of lips and the surroundings.We also introduced a three dimensional display program of facial action. This visualizing system will contribute a communication tool between the dentists and patients.