Three-dimensional Virtual Planning Research Articles

Automated condylar seating assessment using a deep learning-based three-step approach

ObjectivesIn orthognatic surgery, one of the primary determinants for reliable three-dimensional virtual surgery planning (3D VSP) and an accurate transfer of 3D VSP to the patient in the operation room is the condylar seating. Incorrectly seated condyles would primarily affect the accuracy of maxillary-first bimaxillary osteotomies as the maxillary repositioning is dependent on the positioning of the mandible in the cone-beam computed tomography (CBCT) scan. This study aimed to develop and validate a novel tool by utilizing a deep learning algorithm that automatically evaluates the condylar seating based on CBCT images as a proof of concept.Materials and methodsAs a reference, 60 CBCT scans (120 condyles) were labeled. The automatic assessment of condylar seating included three main parts: segmentation module, ray-casting, and feed-forward neural network (FFNN). The AI-based algorithm was trained and tested using fivefold cross validation. The method’s performance was evaluated by comparing the labeled ground truth with the model predictions on the validation dataset.ResultsThe model achieved an accuracy of 0.80, positive predictive value of 0.61, negative predictive value of 0.9 and F1-score of 0.71. The sensitivity and specificity of the model was 0.86 and 0.78, respectively. The mean AUC over all folds was 0.87.ConclusionThe innovative integration of multi-step segmentation, ray-casting and a FFNN demonstrated to be a viable approach for automating condylar seating assessment and have obtained encouraging results.Clinical relevanceAutomated condylar seating assessment using deep learning may improve orthognathic surgery, preventing errors and enhancing patient outcomes in maxillary-first bimaxillary osteotomies.

Improved stability of open bite deformities: taking control of the transverse width using digital technology and robotic archwire bending

Many factors need to be considered when selecting the treatment protocol for the surgical correction of skeletal open bite deformities. In order to achieve stable long-term results, it is essential to explore the origin of the open bite, including any dysfunction of the temporomandibular joint or tongue and compromised nasal breathing, in addition to the skeletal deformity. Recurrence of a skeletal open bite is associated with relapse of the expanded transverse width. Three-dimensional virtual planning allows different treatment options to be explored and final decisions to be made together with the orthodontist who also designs the patient’s digital occlusion. This study presents a treatment protocol for predictable and stable widening of the maxillary transverse width over the long term, involving premolar extraction and rounding and shortening of the upper dental arch by advancing the molar segments. The stability of inter-canine, inter-premolar, and inter-molar distances, as well as overjet and overbite, were measured in 16 patients treated with this technique; measurements were obtained pre- and post-surgery, and the mean follow-up was 43 months. Orthodontic treatment was designed digitally and finished with robotically bent wires (SureSmile), which allowed exact planning of the overall treatment until debonding, thus making orthognathic surgery more predictable for the patient. The changes in transverse width were significant and stable over time.

Symmetry of the left and right tibial plafond; a comparison of 75 distal tibia pairs.

Tibia plafond or pilon fractures present a high level of complexity, making their surgical management challenging. Three-Dimensional Virtual Planning (3DVP) can assist in preoperative planning to achieve optimal fracture reduction. This study aimed to assess the symmetry of the left and right tibial plafond and whether left-right mirroring can reliably be used. Bilateral CT scans of the lower limbs of 75 patients without ankle problems or prior fractures of the lower limb were included. The CT images were segmented to create 3D surface models of the tibia. Subsequently, the left tibial models were mirrored and superimposed onto the right tibia models using a Coherent Point Drift surface matching algorithm. The tibias were then cut to create bone models of the distal tibia with a height of 30mm, and correspondence points were established. The Euclidean distance was calculated between correspondence points and visualized in a boxplot and heatmaps. The articulating surface was selected as a region of interest. The median left-right difference was 0.57mm (IQR, 0.38 - 0.85mm) of the entire tibial plafond and 0.53mm (IQR, 0.37 - 0.76mm) of the articulating surface. The area with the greatest left-right differences were the medial malleoli and the anterior tubercle of the tibial plafond. The tibial plafond exhibits a high degree of bilateral symmetry. Therefore, the mirrored unfractured tibial plafond may be used as a template to optimize preoperative surgical reduction using 3DVP techniques in patients with pilon fractures.

Quantifying the Differences between 3D Virtual Planning and Attained Postoperative Reduction on CT for Patients with Tibial Plateau Fractures; a Clinical Feasibility Study.

Background: Three-Dimensional Virtual Planning (3DVP) has been proven to be effective for limiting intra-articular screw penetration and improving the quality of reduction for numerous fractures. However, the value of 3DVP for patients with tibial plateau fractures has yet to be determined. Purposes: The research question of this study is: Can Computed Tomography Micromotion Analysis (CTMA) provide a reliable quantification of the difference between 3DVP and the postoperative reduction on CT for tibial plateau fractures? Methods: Nine consecutive adult patients who received surgical treatment for a tibial plateau fracture and received pre- and postoperative CT scans were included from a level I trauma center in the Netherlands. The preoperative CT scans of the patients were uploaded in a 3DVP software. In this software, fracture fragments were reduced and the reduction was saved as a 3D file (STL). The quality of the reduction from the 3DVP software was compared with the postoperative results using CT Micromotion Analysis (CTMA). In this analysis, the translation of the largest intra-articular fragment was calculated by aligning the postoperative CT with the 3DVP. Coordinates and measurement points were defined in the X, Y, and Z axes. The combined values of X and Y were used to define the intra-articular gap. The Z-axis was defined as the line from cranial to caudal and was used to define intra-articular step-off. Results: The intra-articular step-off was 2.4 mm (Range 0.5-4.6). Moreover, the mean translation of the X-axis and Y-axis, which was defined as the intra-articular gap, was 4.2 mm (Range 0.6-10.7). Conclusions: 3DVP provides excellent insight into the fracture and its fragments. Utilizing the largest intra-articular fragment, it is feasible to quantify the difference between 3DVP and a postoperative CT using CTMA. A prospective study to further analyze the use of 3DVP in terms of intra-articular reduction and surgical and patient-related outcomes has been started by our team.

Accuracy of Orthognathic Surgical Planning using Three-dimensional Virtual Techniques compared with Conventional Two-dimensional Techniques: a Systematic Review.

The objective was to assess the accuracy of orthognathic surgical planning using three-dimensional virtual planning compared with conventional two-dimensional planning. MEDLINE (PubMed), Embase and Cochrane Library search combined with hand-search of relevant journals was conducted to identify randomized controlled trials (RCTs) published in English through August 2nd, 2022. Primary outcomes included postsurgical accuracy of hard and soft tissue. Secondary outcomes included treatment planning time, intraoperative time, intraoperative blood loss, complications, financial expenses, and patient-reported outcome measures (PROMs). Quality and risk-of-bias assessment were evaluated by Cochrane risk of bias tool and GRADE system. Seven RCTs characterised by low, high, and unclear risk of bias fulfilled inclusion criteria. Included studies disclosed conflicting results regarding accuracy of hard and soft tissue as well as treatment planning time. The intraoperative time was shortened, and financial expenses were increased with three-dimensional virtual surgical planning (TVSP), while no planning-related complications were revealed. Comparable improvement in PROMs were reported with TVSP and two-dimensional planning. Future orthognathic surgical planning will indisputable be performed by three-dimensional virtual planning. The financial expenses, treatment planning time, and intraoperative time will therefore probably decrease due to further development of three-dimensional virtual planning techniques. The hard and soft tissue accuracy between planned position and achieved surgical outcome seems to be improved by three-dimensional virtual planning compared with two-dimensional planning, although results are inconsistent. Further development of three-dimensional virtual planning involving cutting guides and patient-specific osteosynthesis plates are therefore needed to improve the accuracy of orthognathic surgical planning.

Three-dimensional planning accuracy and follow-up of Le Fort I osteotomy in cleft lip/palate patients.

ObjectivesOur aim was to determine the accuracy of the three-dimensional (3D) virtual planning and stability of LeFort I osteotomy in cleft lip and/or palate patients (CLP) using a validated 3D method. Materials and methodsEight patients with a history of cleft lip/palate treated with LeFort I osteotomy for maxillary hypoplasia between January 2016 and April 2020 were included in this retrospective study. Three-dimensional virtual planning was performed using Proplan software then transferred to the operation theater via 3D printed occlusal wafers. The accuracy of the 3D planning and the 1-year stability of the maxilla were evaluated by means of a validated semiautomatic stepwise module in Amira software resulting into 3 linear measurements: anterior/posterior, medial/lateral, superior/inferior and 3 rotational measurements: pitch, roll, yaw. ResultsThe largest mean absolute difference (MAD) for accuracy assessment was found in the A/P direction (2.75mm±2.25 mm) and in pitch (3.23°±2.11°). For A/P translation, an error of >2 mm was observed in 5(62.5%), for S/I translation an error of >2 mm was observed in 4(50.0%) of the 8 patients, whereas for pitch 3 patients(37,5%) showed an error >4° At one year follow-up, the largest linear and rotational MAD was found in the A/P direction (1.20mm±0.92 mm) and in pitch (3.31°±2.31°). ConclusionsFindings of this study show that 3D virtual computer-assisted orthognathic surgery enables an accurate repositioning of the hypoplastic maxilla in CLP patients. However, A/P translations and pitch rotations remain challenging to achieve during surgery. These movements were also found to be least stable at one year follow-up.

Entry Point Variation in the Osseous Fixation Pathway of the Anterior Column of the Pelvis-A Three-Dimensional Analysis.

Fractures of the superior pubic ramus can be treated with screw insertion into the osseous fixation pathway (OFP) of the anterior column (AC). The entry point determines whether the screw exits the OFP prematurely. This can be harmful when it enters the hip joint or damages soft tissues inside the lesser pelvis. The exact entry point varies between patients and can be difficult to ascertain on fluoroscopy during surgery. The aim of this study was to determine variation in the location of the entry point. A retrospective single center study was performed at a level 1 trauma center in the Netherlands. Nineteen adult patients were included with an undisplaced fracture of the superior pubic ramus on computer tomography (CT)-scan. Virtual three-dimensional (3D) models of the pelvises were created. Multiple screws were placed per AC and the models were superimposed. A total of 157 screws were placed, of which 109 did not exit the OFP prematurely. A universally reproducible entry point could not be identified. A typical crescent shaped region of entry points did exist and was located more laterally in females when compared to males. Three-dimensional virtual surgery planning can be helpful to identify the ideal entry points in each case.

Surgical Accuracy of 3D Virtual Surgery and CAD/CAM-Assisted Orthognathic Surgery for Skeletal Class III Patients.

Orthognathic surgery is an effective surgical method to achieve functionality and facial esthetics for mandibular prognathism. If surgery is performed with a conventional method, errors may occur in the surgical preparation process and the surgical procedures, and there is a limitation in that the accuracy of surgery is determined according to the surgeon's experience and tactual sense. However, with the recent development of three-dimensional (3D) virtual planning and CAD/CAM technology, more 3D and predictable surgical planning and more accurate and time-saving surgery have become possible. The purpose of this study is to evaluate the surgical accuracy of 3D Virtual Surgery, CAD/CAM-Assisted Orthognathic surgery for Skeletal Class III Patients. The study included 18 patients who had undergone orthognathic surgery for skeletal class III malocclusion from January 2020 to December 2021. To evaluate the accuracy of the virtual planning, 3D facial cone-beam computed tomography taken immediately after surgery (T1) and virtual surgery data (Tv) were superimposed in each patient. Landmarks were set on each of the maxillary segment, mandibular distal segment, and left and right mandibular proximal segment, and the difference between T1 and Tv was compared 3D on the x , y , and z -axis. (ΔT: T1-Tv). As a result, the average distance between Tv and T1 at each landmark, all landmarks except for the posterior nasal spine of the maxillary segment showed <1mm. In particular, the differences across the x and z -axis were very small, while the difference across the y -axis tend to be large. The comparison of the position of each segment in virtual surgery and actual surgery was as follows. It can be seen that all segments were located slightly downward, and the medial pole of the mandibular proximal segment was located posterolateral and the lateral pole was located anteromedial after the actual surgery compared with the virtual planning. It means that the proximal segment was slightly rotated, but the difference was within 1mm, so it can be considered that the surgery was accurate. Base on this study, orthognathic surgery using 3D virtual surgery planning and CAD/CAM technologies was very accurate. By applying these cutting-edge technologies to clinical practice, it was possible not only to increase the predictability of surgery but also to improve the convenience of surgery. Therefore, it is thought that it will be important for clinicians to make continuous efforts to applicate cutting-edge technologies to be developed in the future to patient diagnosis and surgery.

Surgical accuracy in 3D planned bimaxillary osteotomies: intraoral scans and plaster casts as digital dentition models

The aim of this study was to assess whether the use of intraoral scans (IOS) is an eligible alternative to conventional plaster casts in terms of surgical accuracy of three-dimensionally planned bimaxillary osteotomies. This retrospective cohort study included patients who underwent bimaxillary surgery between 2016 and 2020 in the Department of Oral and Maxillofacial Surgery at Radboud University Medical Center, Nijmegen. Three-dimensional virtual planning was performed with the use of plaster casts in one group and IOS in the other group. Cone beam computed tomography scans were acquired preoperatively and at 1 week following surgery. By using voxel-based matching, the maxillary movements were quantified in six degrees of freedom. The primary outcome variable, surgical accuracy, was defined as the difference between the planned maxillary movements and those achieved. Of 152 patients, 113 were documented with plaster casts and 39 with IOS. The surgical accuracy was comparable in terms of maxillary vertical, sagittal, and transverse translations, as well as roll and yaw. Maxillary pitch (difference 0.55 ± 0.26°; P = 0.001) was in favour of the IOS group. This study demonstrated that IOS can be used as an alternative to conventional plaster casts in the three-dimensional planning of bimaxillary osteotomies.

Simultaneous Le Fort I osteotomy and zygomatic implant placement

The aim of this retrospective study was to evaluate the outcomes of simultaneous LeFort I osteotomy and zygomatic/dental implant placement for oral rehabilitation of patients with extremely atrophic/dysmorphic edentulous maxilla.Simultaneous LeFort I osteotomy and zygomatic/dental implant placement was performed with patient-specific anatomical models and surgical guides produced through three-dimensional virtual planning methods. All patients received their final prosthesis, with immediate loading, on the day after surgery. The primary outcome variables were the implant survival rate, and the incidence of intra/postoperative complications. In total, 15 zygomatic implants and 33 conventional dental implants were inserted in eight patients. The mean follow-up of the patients was 38.5 months. The implant survival rate was 93.3% for zygomatic implants and 100% for dental implants. No intra/postoperative complications were observed.Simultaneous LeFort I osteotomy associated with zygomatic/dental implant surgery can be considered as a valuable treatment option for rehabilitation of patients with extremely atrophic edentulous maxilla and esthetic issues of the face.

3D virtual pre-operative planning may reduce the incidence of dorsal screw penetration in volar plating of intra-articular distal radius fractures

PurposeTo evaluate the effect of three-dimensional virtual pre-operative planning (3DVP) on the incidence of dorsal screw penetration after volar plating of distal radius fractures.MethodsA cross-sectional diagnostic imaging study was performed. Twenty out of 50 patients were randomly selected from our index prospective cohort (IPC): a prior study evaluating dorsal tangential views (DTVs) in reducing dorsal screw penetration in internal fixation of intra-articular distal radius fractures using post-operative CT scans to quantify screw protrusion. Pre-operative CTs from this cohort were now used for 3DVP by three experienced orthopaedic trauma surgeons (supplementary video). 3DVP was compared with the corresponding post-operative CT for assessing screw lengths and incidence of dorsal penetration. The Wilcoxon Signed Ranks test was used to compare screw lengths and the Fishers’ exact for incidence of penetration.ResultsThree surgeons performed 3DVP for 20 distal radius fractures and virtually applied 60 volar plates and 273 screws. Median screw length was shorter in the 3DVP when compared to IPC: 18 mm (range, 12–22) versus 20 mm (range, 14–26) (p < 0.001). The number of penetrating screws was 5% (13/273 screws) in the 3DVP group compared to 11% (10/91 screws) in the IPC (p = 0.047). Corresponding to a reduction in incidence of at least one dorsally penetrating screw in 40% of patients in the IPC group, to 18% in the 3DVP group (p = 0.069).ConclusionThree-Dimensional Virtual Pre-Operative Planning (3DVP) may reduce the incidence of dorsally penetrating screws in patients treated with volar plating for intra-articular distal radius fractures.Level of evidence II, diagnostic imaging study.

Contemporary 3D planning for distraction osteogenesis creating predictable outcomes

Distraction osteogenesis is a treatment option for severely hypoplastic jaws meaning large distance jaw repositioning can occur without the need for ‘staged’ osteotomies. We propose utilising a hybrid approach of three-dimensional virtual planning combined with stock distractors as a novel way of reducing operative time and creating predictable outcomes. The distraction is digitally planned to give the ideal position of the distractors and correct vector of distraction. A stereolithic model is fabricated and used to bend the stock distractor plates pre-operatively to ensure good adaptation, with minimal bending required intra-operatively. A custom bite jig positions the distractors and ensures that the vector is as planned. Stock distraction plates are time consuming and challenging to adapt intra-operatively, hence the ability to move this stage of the operation out of theatre reduces the operative time and allows accurate, aesthetic results.

Three-dimensional virtual planning in mandibular advancement surgery: Soft tissue prediction based on deep learning

The study aimed at developing a deep-learning (DL)-based algorithm to predict the virtual soft tissue profile after mandibular advancement surgery, and to compare its accuracy with the mass tensor model (MTM).Subjects who underwent mandibular advancement surgery were enrolled and divided into a training group and a test group. The DL model was trained using 3D photographs and CBCT data based on surgically achieved mandibular displacements (training group). Soft tissue simulations generated by DL and MTM based on the actual surgical jaw movements (test group) were compared with soft-tissue profiles on postoperative 3D photographs using distance mapping in terms of mean absolute error in the lower face, lower lip, and chin regions.133 subjects were included — 119 in the training group and 14 in the test group. The mean absolute error for DL-based simulations of the lower face region was 1.0 ± 0.6 mm and was significantly lower (p = 0.02) compared with MTM-based simulations (1.5 ± 0.5 mm). ConclusionThe DL-based algorithm can predict 3D soft tissue profiles following mandibular advancement surgery. With a clinically acceptable mean absolute error. Therefore, it seems to be a relevant option for soft tissue prediction in orthognathic surgery. Therefore, it seems to be a relevant options.

Registration of magnetic resonance and computed tomography images in patients with oral squamous cell carcinoma for three-dimensional virtual planning of mandibular resection and reconstruction

The aim of this study was to evaluate and present an automated method for registration of magnetic resonance imaging (MRI) and computed tomography (CT) or cone beam CT (CBCT) images of the mandibular region for patients with oral squamous cell carcinoma (OSCC). Registered MRI and (CB)CT could facilitate the three-dimensional virtual planning of surgical guides employed for resection and reconstruction in patients with OSCC with mandibular invasion. MRI and (CB)CT images were collected retrospectively from 19 patients. MRI images were aligned with (CB)CT images employing a rigid registration approach (stage 1), a rigid registration approach using a mandibular mask (stage 2), and two non-rigid registration approaches (stage 3). Registration accuracy was quantified by the mean target registration error (mTRE), calculated over a set of landmarks annotated by two observers. Stage 2 achieved the best registration result, with an mTRE of 2.5±0.7mm, which was comparable to the inter- and intra-observer variabilities of landmark placement in MRI. Stage 2 was significantly better aligned compared to all approaches in stage 3. In conclusion, this study demonstrated that rigid registration with the use of a mask is an appropriate image registration method for aligning MRI and (CB)CT images of the mandibular region in patients with OSCC.

Improving Aesthetic Outcome in Managing Acute and Chronic Upper and Midface Deformities Using Computer Assisted Planning

Surgical procedures in the facial region are associated bya variety of difficulties. The anatomy of the maxillofacialregion, the complexity of the bony architecture as well as theesthetic implications.The three dimensional imaging and 3D printing, havebeen applied for the restoration the complex anatomy ofcraniofacial structures. In addition, mirror-imaging techniquesadvocating 3D computed tomographic (CT) scanning and 3Dprinting can maximize the surgical outcome on both thefunctional and esthetic reconstruction levels. A syntheticscaffold can be pre-molded to the individual prototype skullmodel to resemble the anatomic contour before applying it tocover the orbital defects.Our aim is to show the importance and present our experiencewith three-dimensional virtual planning in solving avariety of acute and chronic clinical deformities within thescope of trauma in the cranio maxillofacial region.25 patients were retrospectively recruited. Mean age was33.5 years (range 13-59), male: female ratio = 2.6:1 (18:7).Eleven patients had acute injuries (44%) while the remaining14 patients (56%) had chronic (malunited) fractures performedin 2 different centers treating maxillofacial deformities operatedutilizing 3D planning protocols.The advocation of the virtual planning techniques, threedimension printing and printed custom implant enabled anaccurate reduction and fixation procedure of complex acuteand chronic complex upper and midface fracture, which isreflected in very satisfactory aesthetic outcome.

Splintless surgery using patient-specific osteosynthesis in Le Fort I osteotomies: a randomized controlled multi-centre trial

The accuracy of orthognathic surgery has improved with three-dimensional virtual planning. The translation of the planning to the surgical result is reported to vary by >2mm. The aim of this randomized controlled multi-centre trial was to determine whether the use of splintless patient-specific osteosynthesis can improve the accuracy of maxillary translation. Patients requiring a Le Fort I osteotomy were included in the trial. The intervention group was treated using patient-specific osteosynthesis and the control group with conventional osteosynthesis and splint-based positioning. Fifty-eight patients completed the study protocol, 27 in the patient-specific osteosynthesis group and 31 in the control group. The per protocol median anteroposterior deviation was found to be 1.05mm (interquartile range (IQR) 0.45–2.72mm) in the patient-specific osteosynthesis group and 1.74mm (IQR 1.02–3.02mm) in the control group. The cranial–caudal deviation was 0.87mm (IQR 0.49–1.44mm) and 0.98mm (IQR 0.28–2.10mm), respectively, whereas the left–right translation deviation was 0.46mm (IQR 0.19–0.96mm) in the patient-specific osteosynthesis group and 1.07mm (IQR 0.62–1.55mm) in the control group. The splintless patient-specific osteosynthesis method improves the accuracy of maxillary translations in orthognathic surgery and is clinically relevant for planned anteroposterior translations of more than 3.70mm.

How accurate is digital-assisted Le Fort I maxillary osteotomy? A three-dimensional perspective

The aim of this study was to evaluate the surgical accuracy of Le Fort I surgery compared to the three-dimensional (3D) virtual planning. Fifty-five patients (29 males, 26 females; age range 15–58 years) with skeletal class III malocclusion, who underwent bimaxillary surgery were included. A validated 3D accuracy assessment tool was utilized to assess the surgical accuracy of the maxillary positioning. For translational movements, the least amount of error was associated with mediolateral translation, whereas the surgical accuracy for anteroposterior and superoinferior translation showed a tendency towards a more posterior and inferior positioning of the maxilla compared to the planning. For rotational movements, the highest discrepancy was observed for pitch. Linear regression showed increased inaccuracy with increasing advancement for anteroposterior, superoinferior and pitch movements. To conclude, 3D virtual planning of maxilla was generally accurate when compared to achieved outcome for skeletal class III patients undergoing bimaxillary surgery.

An average three-dimensional virtual human skull for a template-assisted maxillofacial surgery.

Although many advances have been made in three-dimensional virtual planning in maxillofacial surgery, facial harmony is still difficult to achieve and is heavily dependent on the surgeon's experience. The aim of the study is to present a method to build up an average three-dimensional virtual human skull to be used as a reference template for bone repositioning and reconstruction during maxillofacial surgical interventions. A total of 20 patients (10 females and 10 males) were selected for the optimal outcome after orthognathic surgery. Postoperative cone-beam computed tomography scans were collected and processed in order to obtain three-dimensional digital models of each skull. For male and female subgroups, the three-dimensional skull models were registered and an average three-dimensional virtual skull model was computed. Deviation color maps were calculated to show differences between each postoperative skull model in the population and the obtained average three-dimensional skull. A clinical use case of genioplasty treatment assisted by the provided average three-dimensional skull template was presented. The overall mean deviation from the average three-dimensional skull model was 1.3 ± 0.6 and 1.6 ± 0.5 mm in male and female subgroups, respectively. For both groups, the greatest deviations were at the area of the mandible, while almost no deviation was found at the zygomatic and orbital areas. In the presented use case, the female average three-dimensional skull model was effectively used for guiding surgical planning. The presented method of obtaining an average three-dimensional virtual human skull may offer the interesting perspective of performing an innovative template-assisted maxillofacial surgery.

Experience of using vascularized bone grafts to treat nonunion fractures and limb bone defects

Background.Vascular bone graft transposition is the one of most effective method of nonunion fracture and bone defect treatment. However, the use of this technique is associated with some difficulties. One is the adjustment of recipient bed size and the graft. The other is the difficulty to reconstruct the alignment and length of bone. A promising method of preparing for the vascular bone graft transposition is virtual three-dimensional planning based on computed tomography data and three-dimensional printing templates.The aimwas to summarize our experience in the treatment of bone nonunion and defects with vascular bone autografts using tree-dimensional virtual planning and printing.Material and methods.We analyzed the treatment process and outcomes of 4 patients with limb bone nonunion and 6 patients with bone defects. In all cases, we used vascular bone grafts. Internal fixation of grafts was used in 7 cases, external fixation was used in 3 cases. At preparation stage in 4 cases, we used tree-dimensional virtual surgery planning and printing templates.Results.One case was diagnosed with bone graft necrosis caused by venous thrombosis. Consolidation was achieved in all patients; a late consolidation was observed in 2 cases. Hematoma in donor area was seen in 2 patients. When using three-dimensional virtual planning and tree-dimensional printing templates, the operation time was decreased by 1 hour 5 minutes. We identified two cases of poor reposition in the group without virtual planning. No poor reposition was observed in the cases where tree-dimensional planning was used.Conclusion.Vascularized bone grafts provide an effective method to treat bone defects and nonunion. But the planning of graft and recipient site sizes is associated with certain difficulties. Our preliminary results have shown that virtual three-dimensional planning and printing allow improving the precision of the surgical procedure and decreasing operative time.

Accuracy of Three-Dimensional Planning in Surgery-First Orthognathic Surgery: Planning Versus Outcome.

BackgroundThe benefit of computer-assisted planning in orthognathic surgery (OGS) has been extensively documented over the last decade. This study aimed to evaluate the accuracy of three-dimensional (3D) virtual planning in surgery-first OGS.MethodsFifteen patients with skeletal class III malocclusion who underwent bimaxillary OGS with surgery-first approach were included. A composite skull model was reconstructed using data from cone-beam computed tomography and stereolithography from a scanned dental cast. Surgical procedures were simulated using Simplant O&O software, and the virtual plan was transferred to the operation room using 3D-printed splints. Differences of the 3D measurements between the virtual plan and postoperative results were evaluated, and the accuracy was reported using root mean square deviation (RMSD) and the Bland-Altman method.ResultsThe virtual planning was successfully transferred to surgery. The overall mean linear difference was 0.88 mm (0.79 mm for the maxilla and 1 mm for the mandible), and the overall mean angular difference was 1.16°. The RMSD ranged from 0.86 to 1.46 mm and 1.27° to 1.45°, within the acceptable clinical criteria.ConclusionIn this study, virtual surgical planning and 3D-printed surgical splints facilitated the diagnosis and treatment planning, and offered an accurate outcome in surgery-first OGS.