A comparative study of the accuracy between two computer-aided surgical simulation methods in virtual surgical planning

ObjectiveThe aim of this retrospective and observational study was to compare the accuracy of two different virtual surgical planning (VSP) protocols, namely, the CASS method and the modified CASS method.Materials and methodsThe patients underwent bimaxillary orthognathic surgery, planned using either the CASS method or the modified CASS method. Linear and angular discrepancies between the VSP outcome and postoperative outcome for both groups were compared for maxilla, mandible, and chin segments. Aside from the comparison between both groups, additional criteria were used to determine the accuracy of the protocol based on a linear and angular difference between planned and actual outcomes of less than 2 mm and 4°, respectively. The intergroup comparisons were performed by one-way ANOVA, with the level of significance set at 5%.ResultsA total of 21 patients, of both genders, were assigned into group I (n = 11), planned with the CASS method, and group II (n = 10), planned with the modified CASS method. Both the CASS and modified CASS methods presented similar accuracy with regard to linear differences for the maxilla, mandible, and chin segments, except for ΔX for the mandibular segment, where the modified CASS method showed slightly better accuracy. However, there was a statistically significant difference with regard to angular differences in the chin segment, with the CASS method shown to be the more accurate. Aside from Δpitch for the chin segment, no linear or angular differences exceeded 2 mm or 4°.ConclusionAlthough statistically significant differences were found with regard to angular measurements in the chin segment, the accuracy of the modified CASS method for virtual planning can be considered as clinically equivalent, with a performance comparable to that of the CASS method.     

Accuracy of virtual surgical planning in bimaxillary orthognathic surgery with mandible first sequence: A retrospective study

The aim of this study was to verify treatment accuracy using virtual surgical planning (VSP) with a mandible-first sequence and strict surgical protocol to determine what surgical and methodological factors might influence outcomes.VSP transfer accuracy was evaluated retrospectively through a modified method involving voxel-based superimposition in patients who had undergone bimaxillary surgery with a mandible-first sequence to correct dentoskeletal deformities. Data analysis showed that the movements planned and those executed were substantially equivalent (p < 0.01), with the exception of mandibular and maxillary sagittal movements that were 0.72 ± 0.90 mm and 1.41 ± 1.04 mm smaller, respectively, than planned.This study showed that a mandible-first sequence is accurate for transferring virtual surgical planning intraoperatively. There are several factors involved in the proper transfer of virtual planning beyond the software, such as surgical technique and sequencing. Inaccurate sagittal movements and maxillary repositioning seem to depend mainly on surgical factors.     

An integrated orthognathic surgery system for virtual planning and image-guided transfer without intermediate splint

Accurate surgical planning and transfer of the planning in orthognathic surgery are very important in achieving a successful surgical outcome with appropriate improvement. Conventionally, the paper surgery is performed based on a 2D cephalometric radiograph, and the results are expressed using cast models and an articulator. We developed an integrated orthognathic surgery system with 3D virtual planning and image-guided transfer. The maxillary surgery of orthognathic patients was planned virtually, and the planning results were transferred to the cast model by image guidance. During virtual planning, the displacement of the reference points was confirmed by the displacement from conventional paper surgery at each procedure. The results of virtual surgery were transferred to the physical cast models directly through image guidance. The root mean square (RMS) difference between virtual surgery and conventional model surgery was 0.75 ± 0.51 mm for 12 patients. The RMS difference between virtual surgery and image-guidance results was 0.78 ± 0.52 mm, which showed no significant difference from the difference of conventional model surgery. The image-guided orthognathic surgery system integrated with virtual planning will replace physical model surgical planning and enable transfer of the virtual planning directly without the need for an intermediate splint.     

Evaluation of the accuracy of virtual planning in bimaxillary orthognathic surgery: a systematic review

The purpose of this research was to evaluate the accuracy of virtual planning in bimaxillary orthognathic surgery in bone by comparing the mean linear and angular measurements of the surgical plan with the actual surgical result. Electronic databases, MEDLINE via PubMed, Web of Science, SCOPUS, the Cochrane Library, grey literature, and the American clinical trials registry (www.ClinicalTrials.gov), were accessed as search engines. The studies consisted of publications on the assessment of accuracy in virtual planning in bimaxillary orthognathic surgery between 2010 and 2020. After application of the eligibility criteria, 26 articles were included, and their quality was evaluated using the methodological index for non-randomised studies (MINORS) tool and Cohen's kappa statistic in the MedCalc program (MedCalc Software Ltd). Evidence obtained by comparing the planning and surgical results, both in the maxilla and mandible, showed that there is great accuracy in virtual planning in bimaxillary orthognathic surgery.     

Comprehensive consideration and design with the virtual surgical planning-assisted treatment for hemifacial microsomia in adult patients

Purpose

Hemifacial microsomia (HFM) is a frequently encountered congenital malformation syndrome involving both hard and soft tissue. Various surgical methods have been described to correct the deformities of HFM in the literature. This study aims to evaluate the therapeutic efficacy for HFM with the assistance of virtual surgical planning (VSP) and 3-dimensionally printed surgical templates.

The evolution of craniofacial resection: A new workflow for virtual planning in complex craniofacial procedures

Complex craniofacial surgery has been later to take advantage of computerized planning than traditional maxillofacial procedures. Virtual reality, 3D model navigation, and bioengineering analyses have changed our approach to the surgical planning of craniofacial resection, increasing the benefits of surgery in terms of accuracy while decreasing complication rate.This study introduces a new workflow for 3D reconstruction, virtual model navigation, and alignment analyses, and demonstrates its successful application in a sample of four patients. A case of squamous cell carcinoma of the maxillary and ethmoid sinus in a 62-year-old patient is presented to evaluate the application of the workflow for a combined transfacial and transcranial resection. Results demonstrate that virtual surgical planning was successfully translated into navigational coordinates and reproduced in the operating room.While the literature provides a wide range of applications of virtual planning for traditional maxillofacial procedures, its introduction for complex craniofacial procedures remains difficult. The presented case shows that it is worth investigating the correlation between virtual reality planning and surgical accuracy for craniofacial resection, and related advantages in terms of surgical safety and improved prognosis.     

Comparison of the accuracy of maxillary position between conventional model surgery and virtual surgical planning

The aim of this study was to determine whether virtual surgical planning (VSP) is an accurate method for positioning the maxilla when compared to conventional articulator model surgery (CMS), through the superimposition of computed tomography (CT) images. This retrospective study included the records of 30 adult patients submitted to bimaxillary orthognathic surgery. Two groups were created according to the treatment planning performed: CMS and VSP. The treatment planning protocol was the same for all patients. Pre- and postoperative CT images were superimposed and the linear distances between upper jaw reference points were measured. Measurements were then compared to the treatment planning, and the difference in accuracy between CMS and VSP was determined using the t-test for independent samples. The success criterion adopted was a mean linear difference of <2 mm. The mean linear difference between planned and obtained movements for CMS was 1.27 ± 1.05 mm, and for VSP was 1.20 ± 1.08 mm. With CMS, 80% of overlapping reference points had a difference of <2 mm, while for VSP this value was 83.6%. There was no statistically significant difference between the two techniques regarding accuracy (P > 0.05).     

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.

数字化模型外科在牙颌面畸形治疗中的应用

目的 ：探讨数字化模型外科在牙颌面畸形治疗中的应用价值。方法 ：选取15例牙颌面畸形患者,通过CT重建模型与激光扫描牙列模型,构建数字化颅颌面-牙列模型,在此基础上进行手术设计,并且三维打印板及导板,指导手术。术后3个月进行面部对称性及手术精确度评价。结果 ：所有患者均顺利完成手术虚拟设计、板和导板三维打印以及正颌手术。偏颌畸形患者术后对称性明显改善,术后CT模型与术前设计比较,最大差异度<2 mm。结论 ：利用数字化模型外科可进行手术设计,模拟,预测,并且可以三维打印板及导板指导手术,在牙颌面畸形的治疗中具有广泛的应用价值,值得临床推广。     

基于虚拟现实技术的正颌手术模拟预测方法的建立

目的:探索建立基于虚拟现实技术的正颌手术模拟研究方法.方法:将颌面畸形患者CT断层图像利用Simplant软件行颅颌面骨组织三维重建,截骨,构建颅颌面骨树状结构模型.在虚拟环境碰撞模型上行上颌骨Le Fort Ⅰ型截骨、双侧下颌支矢状劈开及颏成形的手术模拟.结果:该系统形成的三维立体虚拟影像,可从任意视角观察,清晰逼真.运用系统工具进行骨组织的旋转、平移等手术模拟操作,实现了操作者与模型的交互作用,图像及触觉感知实时反馈,沉浸感强.应用该方法实现了正颌手术设计、虚拟操作及术后效果预测.结论:颅面三维虚拟正颌手术系统可以行正颌手术模拟及手术操作训练,在虚拟环境下实现图像反馈和力、触觉感知的手术模拟,具有较高的临床应用价值.     

Systematic review of the software used for virtual surgical planning in craniomaxillofacial surgery over the last decade

Craniomaxillofacial surgery has been experiencing a deep conceptual change in surgical planning over the last decade, with virtual reality technologies becoming widely adopted. The high demand has led to an exponential increase in available software. The aim of this review was to outline the current literature and provide evidence on the most used software for virtual surgical planning (VSP), and also to define contemporary knowledge on which procedures are more ready candidates for VSP. A search was performed in the major databases, and screening of the results according to the PRISMA statement identified 535 articles reporting the implementation of preoperative VSP during the years 2010–2020. A total of 77 different software programs were identified. The surgical procedures were assigned a standardized nomenclature and further simplified into 10 categories for analysis: temporomandibular joint (TMJ), implants (IMPL), malformations (MALF), reconstruction (REC), oncology (ONCO), oral surgery (ORAL), orthognathic surgery (ORTH), cranial surgery (CRANIO), trauma (TRAUMA), miscellaneous (OTHER). The journals they were reported in and the sample size of each study were also investigated. The results showed that the Materialise suite was the most widespread tool for VSP, with a prevalence of 36.3%, followed by the Geomagic family. Several packages were found to be associated with a specific type of surgical procedure. This review offers a synopsis of the array of VSP software reported in the literature and sets the basis for an informed, evidence-based use of this software in craniomaxillofacial surgery.     

Virtual and traditional surgical planning in orthognathic surgery – systematic review and meta-analysis

Traditional surgical planning (TSP) and virtual surgical planning (VSP) have been used in bimaxillary osteotomy planning. The time is taken in the planning and operating stages, and the working/doctor/total time of either approach are useful determinants of the efficiency of the operating method and quality of care. This systematic review and meta-analysis examined if VSP has a comparative advantage over TSP in the bimaxillary osteotomy. Cochrane Library, PubMed, EMBASE, and Google Scholar were used as databases to collect studies that met the outlined inclusion criteria based on PRISMA. Eight of 759 studies were considered to meet the eligibility criteria, and six fit for meta-analysis. The findings demonstrated significant VSP advantage over TSP in planning time (Z = 3.97 (p < 0.00001), WMD = ?5.29 (CI ?7.90 to ?2.68)). While more time-efficient than TSP, the difference with VSP was not significant during surgery (Z = 0.44 (p = 0.66), WMD = ?0.10 (CI ?0.51 to 0.34)). The study used random effects due to the high I² of the planning mean differences. The continued evolution of VSP and improved application knowledge will be important in reducing the time of planning and surgery, thus improving the outcomes of the complex bimaxillary osteotomy. The current evidence shows that VSP significantly performs better than TSP in reducing the bimaxillary osteotomy planning time, but the timing difference is not significant during surgery. Future analysis will benefit from using studies with standard research and reporting metrics and procedures, thus improving evidence-based clinical practice.     

Single stage treatment of ankylosis of the temporomandibular joint using patient-specific total joint replacement and virtual surgical planning

Ankylosis of the temporomandibular joint (TMJ) is a debilitating condition that can result in pain, trismus, and a poor quality of life. It can be caused by injury, infection, and rheumatoid disease. Current management includes gap arthroplasty, interpositional arthroplasty, and reconstruction. Traditionally, joints are reconstructed using stock implants, or the procedure is done in two stages with an additional computed tomography (CT) scan between the resective and reconstructive procedures and use of stereolithographic models to aid the design of the definitive prostheses. We describe a technique for the resection of ankylosis and reconstruction of the joint in a single operation using virtually designed custom-made implants. Five patients with ankylosis of the TMJ had a single stage operation with reconstruction between 2010 and 2012. All had preoperative high-resolution CT with contrast angiography. During an international web-based teleconference between the surgeon and the engineer a virtual resection of the ankylosis was done using the reconstructed CT images. The bespoke cutting guides and implants were designed virtually at the same time and were then manufactured precisely using computer-aided design and manufacture (CAD-CAM) over 6 weeks. After release of the ankylosis and reconstruction, the patients underwent an exercise regimen to improve mouth opening. Follow-up was for a minimum of 6 months. Four patients had one operation, and one patient had two. Median/Mean maximum incisal opening increased from 0.6 mm before operation to 25 mm afterwards (range 23–27), and there was minimal surgical morbidity. This new method effectively treats ankylosis of the TMJ in a single stage procedure. Fewer operations and hospital stays, and the maintenance of overall clinical outcome are obvious advantages.     

Comparison of the postoperative and follow-up accuracy of articulator model surgery and virtual surgical planning in skeletal class III patients

The aim of this study was to evaluate the postoperative and follow-up accuracy of using an intermediate occlusal splint between articulator model surgery (AMS) and virtual surgical planning (VSP) in double-jaw operations. Thirty skeletal class III patients were randomly allocated to have AMS or VSP. In the AMS group surgical planning was done through conventional articulator model surgery, and an intermediate occlusal splint made of acrylic resin was used. In the VSP group the surgical simulation was done virtually, and the same intermediate splint was used in the software and then fabricated using rapid prototyping technology. Preoperatively, one week postoperatively, and 1∼2-years later we obtained follow-up cone-beam computed tomographic (CT) images of each patient. Absolute linear differences between planned and actual outcomes, as well as planned and follow-up outcomes, were evaluated. There was no significant difference in either postoperative accuracy or follow-up accuracy between the methods, and there was no significant difference in the rate of skeletal relapse. Planning transfer by intermediate splint might therefore be the dominant factor in the final inaccuracies. The potentially greater accuracy of VSP may be realised with the help of new positioning devices instead of an intermediate splint.     

Comprehensive virtual orthognathic planning concept in surgery-first patients

The surgery-first concept is becoming increasingly popular in orthognathic surgery since it offers major advantages such as a reduction of treatment duration and an increase in patient satisfaction by eliminating phases of presurgical orthodontic decompensation. Here, we present a novel interdisciplinary pathway of a fully virtual orthodontic-surgical planning concept in a surgery-first setting using a 3D-printed cutting guide and a customised maxillary implant for the Le Fort I osteotomy as well as a CAD/CAM-based stereolithographic final splint. Patient data from cone-beam computed tomography of the skull and a full arch dental scan were processed using the OnyxCeph^3TM software (Image Instruments). A mutual computer-aided surgical simulation was conducted by the orthodontist and the oral and maxillofacial surgeon to determine the three-dimensional maxillary and mandibular movements. In a separate virtual planning session, the surgeon designed a customised maxillary guide and implant for precise intraoperative transfer (Geomagic Freeform Plus software, 3DSystems). A 3D-printed CAD/CAM-based final splint was fabricated by the orthodontist and used for accurate mandibular repositioning. We established a comprehensive virtual interdisciplinary orthognathic workflow and successfully applied this concept with a high level of accuracy in a series of surgery-first patients with different types of dentofacial anomalies. This novel fully computer-based pathway offers a high potential to improve the outcomes of orthognathic surgery and reduce total treatment time in the management of the orthognathic patient.     

Accuracy of CAD/CAM mandibular reconstruction: A three-dimensional,fully virtual outcome evaluation method

Purpose

Computer-aided design/computer-aided manufacturing (CAD/CAM) methods for mandibular reconstruction have improved both functional and morphological results. We evaluated the accuracy of the CAD/CAM method for mandibular reconstruction and assessed the quantitative and qualitative reproducibility of virtual preoperative planning.

Economic analysis of a low-cost virtual surgical planning protocol for mandibular reconstruction: a case series

The aim of this study was to make an economic analysis and evaluation of a low-cost virtual surgical planning (VSP) protocol that was developed in house, and based on open-source software and a desktop 3-dimensional printer. All eight patients between April 2014 and 2015 who had been treated by mandibular reconstructions with microvascular fibular flaps that had been planned using the protocol were retrospectively analysed for accuracy, time, and cost. Median differences for planned compared with postoperative intercondylar distance, intergonial distance, and gonial angle did not differ significantly. A median (range) labour time of 85 (€57-124) minutes was needed. An evaluation of cost, including labour, showed an additional median (range) cost/patient of € 276 (€257.50-297.25). With the acquisition cost of the 3-dimensional printer omitted, there was a negligible additional cost/patient of €44.75 (€26.25-66). All planning was done by the junior surgeon and there was a steep learning curve. Our new VSP protocol is cost-effective, easy to use, and has an accuracy comparable with that of a standard VSP protocol. To the best of our knowledge this is the first report of an open-source software protocol in which the labour costs of the planning by a surgeon are included.