计算机辅助正颌外科的研究现状

计算机与医学影像技术的快速发展加速了生物医学工程的发展,计算机辅助正颌外科也成为了目前的研究热点。计算机技术贯穿至术前资料的采集与分析、手术计划、手术效果预测和虚拟手术的现实转移整个过程中,具有传统方法无法比拟的优点,是今后正颌外科的发展方向。本文将围绕以上各环节的研究进展作一综述。     

计算机辅助正颌外科手术模拟预测系统的建立

目的:建立一套正颌外科手术模拟系统,为临床提供指导和数据参考,同时为教学提供形象化的教具。方法:在Windows环境下,采用VisualC 语言编制程序,借助彩色图像扫描仪和透射适配器以及数码相机等,将X线片等图象资料输入、储存于计算机,并随时将其调用和显示。在屏幕的X线片图象上进行手术模拟,将照片图象与X线片图象进行配准,获得患者的模拟预测容貌。结果:实现了一套精度高、速度快的正颌外科手术模拟系统。结论:本系统为一套精度高、速度快、效果良好的模拟系统。既为临床和教学提供方便,又为正颌外科领域的科研开辟了一条新路     

计算机模拟正颌外科手术及疗效预测的研究

本文报告作者在个人计算机上开发的一个交互作用系统，用于模拟设计正颌外科手术及预测术后治疗效果。经临床应用取得了满意可靠的结果。     

正颌外科手术的计算机辅助模拟以及预测的准确性评价

目的：计算机辅助模拟正颌外科手术术后软硬组织侧貌,分析术前预测值与术后实际值之间的差异。方法：选取预进行正颌外科手术的牙颌面畸形患者术前去代偿后的侧貌照片和头颅侧位定位片输入Winceph 8.0系统进行头影测量分析,并通过骨段移动来模拟正颌手术,预测术后软硬组织侧貌。将术后6个月以上的头颅侧位定位片输入Winceph 8.0系统进行头影测量分析,选取19项测量参数,将术前预测值和术后实际值进行配对t检验,并评价患者性别以及骨段移动距离对预测结果的影响,评价该预测系统的准确性。结果：硬组织相关的11个测量项目,其术前模拟值和术后实际值间比较均无统计学意义。软组织相关的8个测量项目术前模拟值和术后实际值间比较,仅上唇长有统计学意义（P〈0.05）,其余测量项目均无统计学意义。不同性别的测量结果比较,差异无统计学意义。下颌骨段水平向移动大于8mm组和4-6mm组、6-8mm组相比,上唇长有统计学意义（P〈0.05）。下颌骨段垂直向移动-2-0mm、0-2mm和2-4mm相比,差异无统计学意义。上颌骨段水平向移动2-4mm组与4-6mm组之间,以及垂直向移动-2-0mm与0-2mm之间相比,差异无统计学意义。结论：Winceph8.0系统对正颌手术术后硬组织侧貌的预测准确,对软组织的预测稍显不足,尤其是上唇长。预测结果不受性别影响。下颌骨段后退大于8mm的患者,上唇长的预测准确性较低。     

正颌外科计算机辅助诊断、模拟手术及面像预测系统准确性研究

目的评价计算机专家预测系统的预测准确性及其临床应用的意义和价值。方法通过应用正颌外科专家预测系统（ｏｒｔｈｏｇｎａｔｈｉｃｓｕｒｇｅｒｙｐｒｅｄｉｃａｔｉｏｎｅｘｐｅｒｔｓｙｓｔｅｍ，ＯＳＰＥＳ）对临床３１例牙颌面畸形患者进行了术前诊断，模拟手术和面像预测。结果本系统能够较为准确的预测术后治疗效果，单颌手术平均总准确率达９５％以上，双颌手术达８５％以上。对硬组织预测较软组织预测更为准确。并对影响计算机专家预测系统准确性的因素等进行了讨论。结论计算机专家预测系统是正颌外科预测分析的有价值的工具。     

应用计算机面像预测系统评价正颌手术效果

应用计算机面像预测系统对正颌手术效果评价。方法 ２４例牙颌面畸形患者在正颌手术前运用计算机面像预测系统作模拟手术，得到了模拟手术预测分析后的与预测面像，与术后实际的Ｘ线头颅定位片及彩色面像作比较。结果 预测像与实际软组织像除了下区域各方面都非常相似。     

正颌外科三维立体可视化模拟手术研究

目的：建立基于CT图像数据的计算机辅助三维立体手术模拟系统，为了术前进行精确设计手术方案及达到术后良好效果提供真实可靠依据。方法：应用医学可视化技术和Visual C^**编程语言开发出立体结构三维重建和手术模拟软件，建立以CT数据为信息源的计算机正颌外科立体可视化手术仿真模拟系统，可模拟各种正颌外科手术移动骨质过程，并且以动态动画形式演示，可从任意角度进行观察。结果：该系统建立了颅颌面畸形立体结构模型，以动态形式成功演示了正颌外科截骨移动手术仿真模拟，手术过程真实逼真，立体可视化效果好，应用普通播放软件即可在计算机屏幕上播放模拟正颌外科手术过程，并可预测手术后上下颌咬合状态及手术效果。结论：正颌外科三维立体可视化模拟手术系统的建立，为正颌外科截骨矫治牙颌面畸形术前手术方案制定提供实用有效的技术手段和全心的科学方法，改变仅凭主观经验诊断畸形和设计手术方案的传统模式，可在计算机屏幕前制定手术方案进行医患交流，共同协商，提高了正颌外科手术安全性、精确性和矫治效果。     

双颌畸形同期正颌外科术的护理配合

目的探讨正颌外科手术同期矫治双颌畸形的护理方法。方法同期行上颌骨LeFortⅠ型骨切开和双侧下颌升支矢状劈开术的双颌畸形患者60例。护士术前对患者行心理护理和手术物品准备;术中查对及建立静脉通道,配合麻醉工作,保证手术仪器运转正常和配套器械的及时提供、密切监视患者生命体征,积极配合止血;术后指导正确进食方法、伤口护理和术后注意事项。结果60例患者经术前心理护理后心理状态良好;术中出血量130～610mL,平均出血410mL,均无需输血;术后即刻效果均达到术前设计的要求,面形及咬合关系明显改善。结论双颌畸形的同期正颌外科手术矫治术式复杂,需要特殊器械多,术中护士和术者的密切配合,有助于减少出血,使手术顺利进行。双颌畸形患者经术前心理护理后可减轻患者心理负担。     

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目的评价计算机模拟系统对骨性安氏Ⅲ类错[牙合]畸形正颌术前预测的准确性及其,临床应用价值。方法选择2011年1月至2013年1月到沈阳市口腔医院及中国医科大学附属口腔医院口腔颌面外科就诊的骨性安氏Ⅲ类错目合畸形患者30例,所有患者均拍摄术前、术后CT。利用计算机模拟系统模拟手术和面像预测,并与术后实际效果进行比较。结果30例患者模拟预测与实际结果比较,所有软、硬组织测量参数差异均无统计学意义（P〉O．05）。结论计算机模拟系统能够整合大量医学影像信息,直观模拟手术并预测手术后软、硬组织的变化,可为骨性安氏Ⅲ类错铪畸形患者正颌手术设计个体化最佳方案提供实用有效的技术及依据。     

计算机模拟系统在牵张成骨技术中应用的临床研究

目的对正颌外科计算机模拟系统在牵张成骨技术应用中的预测准确性及其临床意义和价值进行评价和分析。方法对临床30例行牵张成骨术的牙颌面畸形患者应用正颌外科计算机辅助模拟系统(computer-assisted simulation system for orthognathic surgery,CASSOS)进行术前诊断,模拟手术和面像预测,并与术后实际效果进行比较。结果模拟预测与实际结果比较,除单侧牵张成骨比较时Pog-NB差异存在统计学意义外,其余测量参数差异无统计学意义。结论正颌外科计算机模拟预测系统CASSOS能够较为准确的预测下颌单双侧和上颌牵张成骨术后治疗效果,但是对单侧牵张成骨术后下颌颏部的预测仍有差距。     

Accuracy of computer-assisted orthognathic surgery

Introduction

The purpose of this study was to retrospectively evaluate the difference between the planned and the actual movements of the jaws, using three-dimensional (3D) software for PC-assisted orthognathic surgery, to establish the accuracy of the procedure.

Accuracy of perioperative mandibular positions in orthognathic surgery

Mandibular position is an important parameter used for the diagnosis of dentofacial deformities, as well as for orthognathic surgery planning and execution. Centric relation (anterior and superior relationship of the mandibular condyles interposed by the thinnest portion of their disks against the articular eminencies), centric occlusion (when lower teeth contact upper teeth at centric relation), and maximal intercuspation (complete interdigitation of lower and upper teeth) are not often addressed as factors that influence the results of orthognathic surgery, although these relationships are critical to ensure accuracy during the surgery. The present study assessed occlusal measurements taken before and after the induction of general anaesthesia from consecutive orthognathic surgery subjects. The variables assessed included the differences between these occlusal measurements, patient age, gender, type of deformity, and type of proposed orthognathic surgical procedure. The results demonstrated statistically significant differences for mandibular retrusion from maximal intercuspation to centric occlusion position, whereas the mandible appeared not to change significantly from centric occlusion after the induction of general anaesthesia. Patient age and the type of deformity appeared to influence the results. While in most instances centric occlusion can be adequately reproduced under general anaesthesia, for some specific orthognathic cases more accurate results might be obtained if the mandible-first sequence is used.     

Three-dimensional soft tissue prediction in orthognathic surgery: a clinical comparison of Dolphin,ProPlan CMF,and probabilistic finite element modelling

Three-dimensional surgical planning is used widely in orthognathic surgery. Although numerous computer programs exist, the accuracy of soft tissue prediction remains uncertain. The purpose of this study was to compare the prediction accuracy of Dolphin, ProPlan CMF, and a probabilistic finite element method (PFEM). Seven patients (mean age 18 years; five female) who had undergone Le Fort I osteotomy with preoperative and 1-year postoperative cone beam computed tomography (CBCT) were included. The three programs were used for soft tissue prediction using planned and postoperative maxillary position, and these were compared to postoperative CBCT. Accurate predictions were obtained with each program, indicated by root mean square distances: RMS_Dolphin = 1.8 ± 0.8 mm, RMS_ProPlan = 1.2 ± 0.4 mm, and RMS_PFEM = 1.3 ± 0.4 mm. Dolphin utilizes a landmark-based algorithm allowing for patient-specific bone-to-soft tissue ratios, which works well for cephalometric radiographs but has limited three-dimensional accuracy, whilst ProPlan and PFEM provide better three-dimensional predictions with continuous displacements. Patient or population-specific material properties can be defined in PFEM, while no soft tissue parameters are adjustable in ProPlan. Important clinical considerations are the topological differences between predictions due to the three algorithms, the non-negligible influence of the mismatch between planned and postoperative maxillary position, and the learning curve associated with sophisticated programs like PFEM.     

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牙颌面畸形正颌外科治疗需要根据畸形的情况、治疗的要求以及术前患者的生理、心理状态评估综合制定治疗方案.在术前必须对治疗方案、(牙合)关系的调整、骨切开的部位、骨段移动的方向和距离经过精确的设计.正颌外科的术前设计包括头影描迹设计、预测,计算机辅助设计以及模型外科等.本文结合笔者的临床经验和国内外文献对牙颌面畸形正颌外科治疗的术前设计进行述评,强调了牙颌面畸形正颌外科手术方案的设计原则,提出了计算机辅助外科在正颌外科领域具有显著的优势和广阔的应用前景.     

Effects of orthognathic surgery on oropharyngeal airway: a meta-analysis

Oropharyngeal changes caused by orthognathic surgery have been a concern because the sleep quality of patients may be enhanced or worsened by these changes. The purpose of this meta-analysis was to identify, review and compare scientific literature about changes in airway in adult patients undergoing orthognathic surgery to correct anteroposterior osseous discrepancies. An electronic search of four databases was carried out up to July 2010, with supplemental hand searching of the references of the retrieved articles. Quality assessment of the included articles was carried out. Data were extracted and a meta-analysis was performed. Heterogeneity was assessed amongst the studies and results were presented in forest plots. 49 studies met the inclusion criteria. Only studies with moderate or high methodological soundness were included in the review. Moderate evidence was found to support a significant decrease in the oropharyngeal airway in mandibular setback surgery, a milder decrease in bimaxillary surgery to correct Class III and an increase in maxillomandibular advancement surgery. Evidence is lacking on airway volume changes after orthognathic surgery.     

Comprehensive analysis of soft tissue changes in response to orthognathic surgery: mandibular versus bimaxillary advancement

This study was performed to compare soft tissue changes in response to mandibular and bimaxillary advancement osteotomy. Preoperative and postoperative cone beam computed tomography scans of 24 cases were analysed: 12 underwent bimaxillary advancement and 12 underwent mandibular advancement. The skeletal surgical movements were measured and soft tissue changes were displayed on a three-dimensional colour map. The intensity and shade of the colour indicated the magnitude and direction of the changes. In the bimaxillary advancement group, maxillary advancement was 5.5 ± 2.7 mm with anterior vertical impaction of 2.7 ± 2.5 mm; mandibular advancement was 4.6 ± 3.2 mm. Most of the mediolateral soft tissue changes were limited to the anatomical boundaries of the paranasal region – the columella together with the alar bases of the nose; these showed clear forward movement, which extended to involve most of the cheeks. In the mandibular surgery group, the mean advancement was 3.5 ± 2.6 mm. The chin region, lower lip, and inferior parts of the cheek showed forward shift with minimal changes at the vermilion border, which was only displaced in an upward direction. In conclusion, dense anatomical correspondence is a clinically meaningful method of producing a visual comprehensive analysis of the changes in response to orthognathic surgery.