Chang Yu-Jen, Ruellas Antônio C O, Yatabe Marilia S, Westgate Philip M, Cevidanes Lucia H S, Huja Sarandeep S
Faculty, Department of Orthodontics, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung City, Taiwan, Republic of China.
Professor, Department of Orthodontics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
J Oral Maxillofac Surg. 2017 Oct;75(10):2191-2201. doi: 10.1016/j.joms.2017.05.010. Epub 2017 May 24.
Although computer-aided craniofacial reconstructions allow for simulation of hard tissue changes, the prediction of the final soft tissue facial changes remains a challenge. The purpose of the present study was to evaluate the 3-dimensional (3D) soft tissue changes in patients undergoing 2-jaw orthognathic surgery.
For the present retrospective cohort study, 40 consecutive patients (11 men and 29 women; mean age 23.5 ± 4.9 years) who had undergone 2-jaw orthognathic surgery were selected. We obtained the medical and dental records from 3 weeks before surgery and 6 months after surgery. We used image processing software to segment, superimpose, and quantify the hard and soft tissue displacements in 3 dimensions before and after surgery at 15 paired locations. The soft tissue and hard tissue changes were determined through quantification of homologous landmark displacements between the preoperative and postoperative computed tomography data. We measured the 3D soft and hard tissue changes and the anteroposterior, inferosuperior, and transverse components of the changes. We quantified the ratios between the soft and hard tissue changes, tested Pearson's correlation between these changes, and developed a predictive regression equation for the observations at each location.
We found that soft tissue movement followed the hard tissue movement, with a correlation nearly equal to 0.9 (range 0.85 to 0.98), suggesting that in general the soft tissues of the maxillary and mandibular landmarks are affected similarly by the skeletal movements. The anteroposterior component of the soft tissue 3D displacements followed the hard tissue movement with a ratio greater than 0.9 and with high correlation (r > 0.9) in the mandible.
The results of the present study provide surgeons with a ratio of hard to soft tissue change and the strength of the correlations, which will allow for more accurate 3D predictions for both midline and lateral structures in bimaxillary orthognathic surgical cases. In addition, predictive equations for various landmarks were developed and can be used in computer-based prediction programs to aid in treatment planning of soft tissue changes.
尽管计算机辅助颅面重建能够模拟硬组织变化，但预测最终的软组织面部变化仍是一项挑战。本研究的目的是评估接受双颌正颌手术患者的三维（3D）软组织变化。
在这项回顾性队列研究中，选取了40例连续接受双颌正颌手术的患者（11例男性和29例女性；平均年龄23.5±4.9岁）。我们获取了手术前3周和手术后6个月的医疗和牙科记录。我们使用图像处理软件在手术前后15个配对位置对三维硬组织和软组织位移进行分割、叠加和量化。通过术前和术后计算机断层扫描数据中同源标志点位移的量化来确定软组织和硬组织的变化。我们测量了三维软组织和硬组织变化以及变化的前后、上下和横向分量。我们量化了软组织和硬组织变化之间的比率，测试了这些变化之间的皮尔逊相关性，并为每个位置的观察结果建立了预测回归方程。
我们发现软组织运动跟随硬组织运动，相关性接近0.9（范围为0.85至0.98），这表明一般来说，上颌和下颌标志点的软组织受骨骼运动的影响相似。软组织三维位移的前后分量跟随硬组织运动，比率大于0.9，在下颌骨中相关性较高（r>0.9）。
本研究结果为外科医生提供了硬组织与软组织变化的比率以及相关性强度，这将有助于在双颌正颌手术病例中对中线和外侧结构进行更准确的三维预测。此外，还建立了各种标志点的预测方程，可用于基于计算机的预测程序，以辅助软组织变化的治疗计划。
