Gyawali Rajesh, Pokharel Prabhat Ranjan, Giri Jamal
Department of Orthodontics, College of Dental Surgery, B.P. Koirala Institute of Health Sciences, Dharan 56700, Nepal.
Int J Dent. 2016;2016:3957806. doi: 10.1155/2016/3957806. Epub 2016 Mar 22.
Objective. This study aimed to find out the change in esthetic ratios during rotation of patient's head using a simulation. Materials and Methods. A plaster study model was photographed placing its midline along the long axis of the camera. Then a series of photographs were taken by rotating the model each degree till 10° on both right and left sides. These photographs were digitally measured and the ratio of the maxillary anterior teeth at zero-degree rotation was compared with that at various degrees of rotation. Results. As the model was rotated to the right side till 10°, the ratio of the right lateral to central incisor gradually decreased while the ratio of the left lateral to central incisor gradually increased. However, the ratio of the canine to lateral incisor on both sides gradually increased. Similar results were obtained when the model was rotated to the left side. The ratio of the lateral to central incisor deviated from the acceptable range (±10%) when there was rotation of more than 7°, whereas the ratio of the canine to lateral incisor was within the acceptable range till 10° rotation on either side. Conclusions. Rotation of the model by more than 7° leads to a substantial change in the esthetic ratio.
目的。本研究旨在通过模拟找出患者头部旋转过程中美学比例的变化。材料与方法。拍摄一个石膏研究模型，使其中线沿相机的长轴放置。然后通过将模型左右两侧各旋转1度直至10度拍摄一系列照片。对这些照片进行数字化测量，并将零旋转度时上颌前牙的比例与不同旋转度时的比例进行比较。结果。当模型向右侧旋转至10度时，右侧侧切牙与中切牙的比例逐渐降低，而左侧侧切牙与中切牙的比例逐渐升高。然而，两侧尖牙与侧切牙的比例逐渐升高。当模型向左侧旋转时也获得了类似结果。当旋转超过7度时，侧切牙与中切牙的比例偏离了可接受范围（±10%），而两侧尖牙与侧切牙的比例在两侧旋转至10度时仍在可接受范围内。结论。模型旋转超过7度会导致美学比例发生显著变化。
