Abstract：
Genioplasty is a widely used surgical approach to address chin deformities by performing an osteotomy on the inferior border of the mandible to allow for comprehensive repositioning of the chin. This study aimed to compare the accuracy of freehand chin repositioning with a guided technique that employed specialised surgical guides. For this retrospective study, data from 30 adult patients who underwent orthognathic surgery to correct dentofacial deformities were analysed. All patients underwent virtual planning before surgery, with half of them treated using freehand chin repositioning and the other half using the guided technique. The surgical outcomes were measured and compared with the virtual plan to assess the positional and rotational accuracy of the techniques. In terms of translational assessment, noteworthy values that exceeded clinically acceptable limits were observed only in sagittal movement in the freehand group (0.97 mm, interquartile range (IQR) 0.73-2.29 mm). Regarding rotational accuracy, both groups exhibited an IQR that surpassed acceptable limits for pitch (3.26°, IQR 2.06-5.20 for the guided group and 2.57°, IQR 1.63-4.24° for the freehand group). The Mann-Whitney test indicated no statistical differences between the groups in any translational or rotational assessment. In conclusion, although there was no statistical difference, the guided technique proved effective in achieving clinically acceptable accuracy in all positions and almost all rotations, displaying superior results in sagittal positioning compared with the freehand technique. To fully harness the advantages of guides and to guarantee accuracy in all rotations, we recommend further research involving guides made of more rigid materials, and customised implants.
摘要：
生殖器成形术是一种广泛使用的手术方法，可通过在下颌骨的下边界进行截骨术来解决下巴畸形，以全面重新定位下巴。这项研究旨在比较徒手下巴重新定位与采用专业手术指南的引导技术的准确性。对于这项回顾性研究，分析了30例接受正颌手术矫正牙面畸形的成年患者的数据。所有患者术前进行虚拟规划,其中一半使用手绘下巴重新定位治疗，另一半使用引导技术治疗。测量手术结果，并与虚拟计划进行比较，以评估技术的位置和旋转精度。在翻译评估方面，仅在徒手组矢状运动中观察到超过临床可接受限值的值得注意的值(0.97mm,四分位数间距（IQR）0.73-2.29毫米）。关于旋转精度，两组都表现出超过可接受的间距限制的IQR(3.26°，导向组的IQR2.06-5.20和2.57°，手绘组的IQR1.63-4.24°)。Mann-Whitney检验表明，在任何平移或旋转评估中，组间没有统计学差异。总之,尽管没有统计学差异，该引导技术被证明可以有效地在所有位置和几乎所有旋转中实现临床上可接受的准确性，与徒手技术相比，矢状定位显示出更好的结果。为了充分利用导轨的优势，并保证所有旋转的准确性，我们建议进一步研究涉及由更刚性材料制成的指南，和定制的植入物。
