Computer-assisted Orthognathic Surgery Research Articles

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.

Accuracy of Segmented Le Fort I Osteotomy with Virtual Planning in Orthognathic Surgery Using Patient-Specific Implants: A Case Series.

Background: When maxillary transversal expansion is needed, two protocols of treatment can be used: a maxillary orthodontic expansion followed by a classical bimaxillary osteotomy or a bimaxillary osteotomy with maxillary segmentation. The aim of this study was to assess the accuracy of segmented Le Fort I osteotomy using computer-aided orthognathic surgery and patient-specific titanium plates in patients who underwent a bimaxillary osteotomy for occlusal trouble with maxillary transversal insufficiencies. Methods: A virtual simulation of a Le Fort I osteotomy with maxillary segmentation, a sagittal split ramus osteotomy, and genioplasty (if needed) was conducted on a preoperative three-dimensional (3D) model of each patient’s skull using ProPlan CMF 3.0 software (Materialise, Leuven, Belgium). Computer-assisted osteotomy saw-and-drill guides and patient-specific implants (PSIs, titanium plates) were produced and used during the surgery. We chose to focus on the maxillary repositioning accuracy by comparing the preoperative virtual surgical planning and the postoperative 3D outcome skulls using surface superimpositions and 13 standard dental and bone landmarks. Errors between these preoperative and postoperative landmarks were calculated and compared to discover if segmental maxillary repositioning using PSIs was accurate enough to be safely used to treat transversal insufficiencies. Results: A total of 22 consecutive patients—15 females and 7 males, with a mean age of 27.4 years—who underwent bimaxillary computer-assisted orthognathic surgery with maxillary segmentation were enrolled in the study. All patients presented with occlusion trouble, 13 with Class III malocclusions (59%) and 9 (41%) with Class II malocclusions. A quantitative analysis revealed that, overall, the mean absolute discrepancies for the x-axis (transversal dimension), y-axis (anterior–posterior dimensions), and z-axis (vertical dimension) were 0.59 mm, 0.74 mm, and 0.56 mm, respectively. The total error rate of maxillary repositioning was 0.62 mm between the postoperative cone-beam computed tomography (CBCT) and the preoperatively planned 3D skull. According to the literature, precision in maxilla repositioning is defined by an error rate (clinically relevant) at each landmark of <2 mm and a total error of <2 mm for each patient. Conclusions: A high degree of accuracy between the virtual plan and the postoperative result was observed.

The Contemporary Management of Cleft Lip and Palate and the Role of Artificial Intelligence: A Review

Introduction: Cleft management is an exhaustive process for the patient, the orthodontist, and the caregiver. In recent decades, a wide number of challenges have been addressed with the inclusion of various dental specialties for the detection, diagnosis, and treatment of orofacial clefts. The orthodontist plays a very pivotal role during the overall management of children with cleft lip and palate as they need to make critical decisions for when to intervene orthodontically and at what stage to set priorities for individual treatment goals. Objectives: The objectives of this study were to provide an in-depth review of the evolving role of various disciplines focusing on orthodontics in the management of cleft cases. Methods: A general search was carried out to identify the published data on cleft lip and cleft palate management on PubMed and Scopus until the 1st of June 2021 using keywords such as cleft lip, cleft palate, cleft orthodontics, naso-alveolar molding, and surgical cleft orthodontics. The related literature was then reviewed and analyzed. Results: With improvements in 3D modeling, CT scans of patients can be used to construct precise 3D models, and these can be utilized to demonstrate various clinical issues related to clefts. The orthodontist has a major role in the various stages and steps, follow-up, treatment care, and outcome assessment. With the advent of technological advancements and artificial intelligence, the role is only going to evolve and expand further in the management of the cleft lip and palate. Diagnostic techniques utilizing artificial intelligence to detect cleft during the prenatal period have also been tested and have been shown to have a high rate of accuracy. The evolution of distraction osteogenesis came into the limelight as a revolutionary modality for cleft treatment. Computer-assisted orthognathic surgery is a widely used modality for reshaping the osseous defects of the maxilla in patients with congenital clefts. With the development of additional modalities such as aligners, patients that need to undergo complex orthognathic surgeries can also be treated with aligners without compromising the outcomes. Conclusion: The cleft lip and palate can be managed by a multi-disciplinary team. Orthodontics has an important role in the overall management of a cleft affected individual as they must make critical decisions regarding orthodontic interventions as well as set priorities for each treatment goal. With the advent of technological advancements and artificial intelligence, the diagnosis and management of the cleft lip and palate have become simplified.

Fully automatic segmentation of craniomaxillofacial CT scans for computer-assisted orthognathic surgery planning using the nnU-Net framework.

To evaluate the performance of the nnU-Net open-source deep learning framework for automatic multi-task segmentation of craniomaxillofacial (CMF) structures in CT scans obtained for computer-assisted orthognathic surgery. Four hundred and fifty-three consecutive patients having undergone high-resolution CT scans before orthognathic surgery were randomly distributed among a training/validation cohort (n = 300) and a testing cohort (n = 153). The ground truth segmentations were generated by 2 operators following an industry-certified procedure for use in computer-assisted surgical planning and personalized implant manufacturing. Model performance was assessed by comparing model predictions with ground truth segmentations. Examination of 45 CT scans by an industry expert provided additional evaluation. The model's generalizability was tested on a publicly available dataset of 10 CT scans with ground truth segmentation of the mandible. In the test cohort, mean volumetric Dice similarity coefficient (vDSC) and surface Dice similarity coefficient at 1mm (sDSC) were 0.96 and 0.97 for the upper skull, 0.94 and 0.98 for the mandible, 0.95 and 0.99 for the upper teeth, 0.94 and 0.99 for the lower teeth, and 0.82 and 0.98 for the mandibular canal. Industry expert segmentation approval rates were 93% for the mandible, 89% for the mandibular canal, 82% for the upper skull, 69% for the upper teeth, and 58% for the lower teeth. While additional efforts are required for the segmentation of dental apices, our results demonstrated the model's reliability in terms of fully automatic segmentation of preoperative orthognathic CT scans. • The nnU-Net deep learning framework can be trained out-of-the-box to provide robust fully automatic multi-task segmentation of CT scans performed for computer-assisted orthognathic surgery planning. • The clinical viability of the trained nnU-Net model is shown on a challenging test dataset of 153 CT scans randomly selected from clinical practice, showing metallic artifacts and diverse anatomical deformities. • Commonly used biomedical segmentation evaluation metrics (volumetric and surface Dice similarity coefficient) do not always match industry expert evaluation in the case of more demanding clinical applications.

Maintaining the space between the mandibular ramus segments during bilateral sagittal split osteotomy does not influence the stability

Three-dimensional computer-assisted orthognathic surgery allows to simulate the space between the mandibular ramus segments, i.e. intersegmental gap, for the correction of facial asymmetry. The purposes of the study were to estimate the screws- and mandible bone-related changes from the early postoperative period to the period after the debonding and to measure the association between the intersegmental gap volume and the screws- and mandible bone-related changes. This cone-beam computed tomography (CBCT)-assisted retrospective study assessed the stability of the bicortical positional screw fixations in maintaining the space between the mandibular ramus segments after bilateral sagittal split osteotomy in correction of 31 patients with malocclusion and facial asymmetry. The primary predictor variable was the CBCT-based intersegmental gap volume at early postoperative period (T1). The primary outcome variables were CBCT-based screws- and bone-related measurement changes between the T1 and T2 (at debonding) periods. No significant differences were observed in screws-related linear and angular measurements between T1 and T2 virtual models. Some of mandible bone-related linear and angular measurements had significant differences (P<0.05) between the T1 and T2 images, but with no clinical repercussion such as need of revisionary surgery. The gap volume and the screws- and bone-related changes had no significant correlations. This study contributes to the multidisciplinary-related literature by demonstrating that the bicortical positional screws-based fixation technique in maintaining the three-dimensional-simulated space between the mandibular ramus segments is a stable and clinically acceptable option for correction of facial asymmetry associated with malocclusion, regardless of intersegmental gap size.

Precision of orthognathic digital plan transfer using patient-specific cutting guides and osteosynthesis versus mixed analogue–digitally planned surgery: a randomized controlled clinical trial

Over the last decade, the accuracy of three-dimensional computer-assisted orthognathic surgery has been investigated extensively. The absence of high-quality controlled trials, limited number of studies overall, and methodological flaws have hindered its use in general clinical practice. The aim of this study was to assess the accuracy of computer-assisted orthognathic surgery compared to the classic occlusal wafers. Eighteen patients were randomly allocated to two groups: CAD/CAM splints and patient-specific osteosynthesis were used for maxillary positioning in group 1; occlusal wafers fabricated on a semi-adjustable articulator were used in group 2. Patients were assessed for linear and angular deviations of maxillary position from the virtual plan using cone beam computed tomography scans. The CAD/CAM group showed mean deviations of 0.26mm vertically, 0.17mm anteroposteriorly, and 0.07mm mediolaterally, while the classic wafer group showed mean deviations of 1.45mm vertically, 1.31mm anteroposteriorly, and 0.71mm mediolaterally. Statistical analysis showed that the proposed workflow provided a significantly more accurate plan transfer compared to classic occlusal wafers. Despite the statistical significance, the clinical significance was less appreciated. However, this new technology facilitated cases with skeletal asymmetry, reduced operating times, and allowed a trainee surgeon to perform the procedure with great accuracy and minimal time. The main limitation was the high cost.

Evaluation of the Accuracy of Virtual Planning in Orthognathic Surgery: A Morphometric Study.

The purpose of this study was to prospectively test the accuracy of computer-aided orthognathic surgery comparing the virtual surgical planning with the three-dimensional (3D) outcome. Patients that underwent computer-assisted orthognathic surgery were retrospectively evaluated. The postoperative results were compared with the surgical plan, superimposing the postoperative computed tomography (CT) scan onto the virtual plan. Surface-based superimpositioning of the postoperative CT scan onto the 3D preoperative plan was carried out to visualize the discrepancy between preoperative virtual plan and postoperative 3D CT result. A total of 17 consecutive patients that underwent two-jaw computer-assisted orthognathic surgery were enrolled in the study.The average linear differences for selected points were <1 mm in 12 patients out of 17. In 5 patients out of 17, the average differences for selected points were <2 mm. An overall high degree of accuracy between the virtual plan and the postoperative result was found.

Quality of life after different approaches of orthognathic surgery: a randomized controlled study.

Over the last decade, the accuracy of 3D computer-assisted orthognathic surgery has been extensively investigated. However, patient-reported outcome measures have been rarely reported for this technology. This study aimed to assess quality of life following orthognathic surgery using CAD/CAM bone splints compared to the classic occlusal wafers in patients with dentofacial deformities. Thirty-two patients were randomly allocated into two groups where group I utilized CAD/CAM splints and patient specific osteosynthesis for maxillary positioning and group II utilized occlusal wafers fabricated on a semi-adjustable articulator. Patients were assessed using orthognathic quality of life Questionnaire (OQLQ) preoperatively and 6 months postoperatively. Mean OQLQ overall score change of 24.375±11.96 took place in group I patients while group II showed a mean change of 23±8.39. The study showed evident improvement in quality of life following orthognathic surgery compared to before surgery. However, computer-assisted surgery did not show any significant improvement over the classic approach.

3D computer-assisted orthognathic surgery

Orthognathic surgery is designed to correct problems of the jaw and face and restore facial harmony. The limitations of orthognathic surgery occur at all steps of the surgical workflow: preoperative planning, simulation, and operation. Many studies have shown the accuracy and advantages of 3 dimensional computer-assisted program for orthognathic surgery. The purpose of this paper is to introduce the accuracy of the maxillary repositioning in patients who underwent orthognathic surgery using a 3 dimensional computer assisted surgery program. The reliability of computer guided orthognathic surgery using splint and surgical guide need to be improved further. The 3 dimensional computer assisted analysis seems to be more precise to interpret than two-dimensional analysis. High-precision planning of orthognathic surgery has predictable results. Three-dimensional computer assisted orthognathic surgery has the following advantages : planned surgical movement is possible, splints guide with CAD/CAM technology; and increase predictable results .Computer assisted simulation surgery ensures accuracy during surgery, thereby facilitating predictable results. It may provide solution that enables surgeon to perform planned surgery more accurately.

Accuracy of computer-assisted orthognathic surgery

IntroductionThe 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. Material and methodsA retrospective study was performed with 49 patients who had undergone PC-guided bimaxillary surgery. The accuracy of the protocol was determined by comparing planned movements of the jaws with the actual surgical movements, analysing frontal and lateral cephalometries. ResultsThe overall results were deemed accurate, and differences among 12 of the 15 parameters were considered nonsignificant. Significant differences were reported for SNA (p = 0.008), SNB (p = 0.006), and anterior facial height (p = 0.033). The latter was significantly different in patients who had undergone genioplasty when compared with patients who had not. ConclusionVirtual surgical planning presented a good degree of accuracy for most of the parameters assessed, with an average error of 1.98 mm for linear measures and 1.19° for angular measures. In general, a tendency towards under-projection in jaws was detected, probably due to imperfect condylar seating. A slight overcorrection of SNA and SNB during virtual planning (approximately 2°) could be beneficial. Further progress is required in the development of 3D simulation of the soft tissue, which currently does not allow an accurate management of the facial height and the chin position.Virtual planning cannot replace the need for constant intraoperative monitoring of the jaws' movements and real-time comparisons between planned and actual outcomes. It is therefore appropriate to leave some margin for correction of inaccuracies in the virtual planning. In this sense, it may be appropriate to use only the intermediate splint, and then use the planned occlusion and clinical measurements to guide repositioning of the second jaw and chin, respectively.

Clinical accuracy of waferless maxillary positioning using customized surgical guides and patient specific osteosynthesis in bimaxillary orthognathic surgery

Computer-assisted planning and surgery for the treatment of orthognathic deformities have been extensively documented over the last decade. Computerized and customized wafers have lacked to improve the accuracy of maxillary positioning, resulting in a drawback of computer-assisted orthognathic surgery. The aim of this study was to determine the accuracy of a new technique of waferless maxillary positioning using customized surgical guides and patient specific osteosynthesis implants in bimaxillary orthognathic surgery.22 consecutive patients were evaluated prospectively by fusing preoperative planning and postoperative outcome using CT scan evaluation. The median deviation of the maxilla position between the preoperative plan and the surgical result was 0.39 mm. The accuracy of left-right-positioning was median 0.30 mm at a range of 0–0.95 mm. Up–down-positioning showed a median accuracy of 0.33 mm at a range of 0–1.22 mm. Higher values were determined for the anterior–posterior-positioning of the maxilla with median 0.7 mm at a range of 0–2.0 mm.The results demonstrate the high predictability of maxillary positioning by CAD/CAM fabricated customized surgical guides and patient specific osteosynthesis. Use of this new digital approach may achieve surgeon independent accuracy of maxillary positioning, facilitating resident training even in the treatment of complex malformations. The high costs, however, may restrict routine use of this technique.

Computer-assisted orthognathic surgery: evaluation of mandible registration accuracy and report of the first clinical cases of navigated sagittal split ramus osteotomy

Intraoperative navigation is a helpful tool in complex anatomical regions or procedures. The mobility of the mandible in relation to the skull base limits the use of navigation tools on the lower jaw if the reference device is installed on the forehead. A new workflow that allows navigation-assisted sagittal split osteotomy in orthognathic surgery using a separate non-invasive mandibular registration technique has been developed. An evaluation of accuracy in different anatomical regions and with different registration techniques was performed on skull models and skulls with movable mandibles. The mean inaccuracy was 1.51mm, with no significant difference between anatomical sites. Using a splint-based reference device allows the movable mandible to be registered independently from the midface. Registration using metal points in the splint provides higher accuracy than using interdental anatomical landmarks. The workflow could be transferred successfully to patient treatment. Navigation-assisted osteotomy by Obwegeser–Dal Pont technique was performed without any complication in six patients. The mean deviation from the planned osteotomy line was 1.52mm. The navigated sagittal split ramus osteotomy seems to be a suitable technique to increase patient safety.

Computer-Assisted Orthognathic Surgery for Patients with Cleft Lip/Palate: From Traditional Planning to Three-Dimensional Surgical Simulation.

BackgroundAlthough conventional two-dimensional (2D) methods for orthognathic surgery planning are still popular, the use of three-dimensional (3D) simulation is steadily increasing. In facial asymmetry cases such as in cleft lip/palate patients, the additional information can dramatically improve planning accuracy and outcome. The purpose of this study is to investigate which parameters are changed most frequently in transferring a traditional 2D plan to 3D simulation, and what planning parameters can be better adjusted by this method.Patients and MethodsThis prospective study enrolled 30 consecutive patients with cleft lip and/or cleft palate (mean age 18.6±2.9 years, range 15 to 32 years). All patients received two-jaw single-splint orthognathic surgery. 2D orthodontic surgery plans were transferred into a 3D setting. Severe bony collisions in the ramus area after 2D plan transfer were noted. The position of the maxillo-mandibular complex was evaluated and eventually adjusted. Position changes of roll, midline, pitch, yaw, genioplasty and their frequency within the patient group were recorded as an alternation of the initial 2D plan. Patients were divided in groups of no change from the original 2D plan and changes in one, two, three and four of the aforementioned parameters as well as subgroups of unilateral, bilateral cleft lip/palate and isolated cleft palate cases. Postoperative OQLQ scores were obtained for 20 patients who finished orthodontic treatment.Results83.3% of 2D plans were modified, mostly concerning yaw (63.3%) and midline (36.7%) adjustments. Yaw adjustments had the highest mean values in total and in all subgroups. Severe bony collisions as a result of 2D planning were seen in 46.7% of patients. Possible asymmetry was regularly foreseen and corrected in the 3D simulation.ConclusionBased on our findings, 3D simulation renders important information for accurate planning in complex cleft lip/palate cases involving facial asymmetry that is regularly missed in conventional 2D planning.

Three-dimensional computer-assisted orthognathic surgery: experience of 37 patients.

Three-dimensional computer-assisted orthognathic surgery has been applied to improve planning and outcome. This study presents our experience with this promising modality for simulation of surgery, prefabrication of positioning guides, and navigation of the surgery. Thirty-seven patients who received surgical simulation and intraoperative navigation for 2-jaw orthognathic surgery were recruited. Preoperative 3-dimensional cone-beam computed tomographic images were used for surgical simulation and design of intraoperative guidance. An initial surgical plan was developed and transferred for 3-dimensional virtual surgery. Modification of the surgical plan was made if facial symmetry and skeletal harmony or collision of ramus segments were concerned. The result of virtual surgery was used to design and manufacture positioning guides and perform preoperative navigation planning. During the operation, the positioning guides were used to transfer the virtual planning to actual surgery, and a real-time navigation system was used to confirm the predetermined position of the maxillomandibular complex. For assessment of the computer-assisted surgical system, the simulation image was superimposed to the postoperative image for comparison. The computer-assisted orthognathic surgery was successfully carried out in all patients. The initial surgical plan was modified in 17 patients in whom the position of maxillomandibular complex was changed. The positioning guides were helpful in controlling the spatial position of the maxillomandibular complex. The BrainLabTR navigation system was useful to further confirm the position of the facial bone. Superimposition of the simulation and postoperative images revealed satisfactory result with acceptable errors. The difference ranged from 0.05 to 1.46 mm, with a mean value of 0.66 mm, for patients using the positioning guides; and the difference ranged from 0.07 to 2.30 mm, with a mean value of 1.20 mm, for patients using the navigation system. Overall, patient and doctor satisfaction was high. This computer-assisted orthognathic surgery system helps to improve surgical planning, reduce surgical difficulty, facilitate positioning and fixation of the maxillomandibular complex, and improve outcome.

Three-dimensional computer-assisted surgical simulation and intraoperative navigation in orthognathic surgery: A literature review

By incorporating three-dimensional (3D) imaging and computer-aided design and manufacturing techniques, 3D computer-assisted technology has been applied widely to provide accurate guidance for assessment and treatment planning in clinical practice. This technology has recently been used in orthognathic surgery to improve surgical planning and outcome. The modality will gradually become popular. This study reviewed the literature concerning the use of computer-assisted techniques in orthognathic surgery including surgical planning, simulation, intraoperative translation of the virtual surgery, and postoperative evaluation. A Medline, PubMed, ProQuest, and ScienceDirect search was performed to find relevant articles with regard to 3D computer-assisted orthognathic surgery in the past 10 years. A total of 460 articles were revealed, out of which 174 were publications addressed the topic of this study. The purpose of this article is to present an overview of the state-of-art methods for 3D computer-assisted technology in orthognathic surgery. From the review we can conclude that the use of computer-assisted technique in orthognathic surgery provides the benefit of optimal functional and aesthetic results, patient satisfaction, precise translation of the treatment plan, and facilitating intraoperative manipulation.

Computer-assisted orthognathic surgery for correction of facial asymmetry: results of a randomised controlled clinical trial

In this randomised controlled clinical trial, 2 homogeneous groups of patients with facial asymmetry (n=10 in each) were treated by either classic or computer-assisted orthognathic corrective surgery. Differences between the 2 groups in the alignment of the lower interincisal point (p=0.03), mandibular sagittal plane (p=0.01), and centring of the dental midlines (p=0.03) were significant, with the digital planning group being more accurate.

Computer-Assisted Orthognathic Surgery Combined With Fibular Osteomyocutaneous Flap Reconstruction to Correct Facial Asymmetry and Maxillary Defects Secondary to Maxillectomy in Childhood

Maxillectomy in childhood not only causes composite primary defects but also secondary malformation of the middle and lower face. In the case presented, we introduced computer-assisted planning and simulation of orthognathic surgery combined with fibular osteomyocutaneous flap reconstruction to correct complex craniofacial deformities. Virtual orthognathic surgery and maxillary reconstruction surgery were undertaken preoperatively. LeFort I osteotomy, with bilateral sagittal split ramus osteotomy and lower border ostectomy, was performed to correct malocclusion and facial asymmetry. Maxillary reconstruction was accomplished using a fibular osteomyocutaneous flap. The patient recovered uneventfully with an adequate aesthetic appearance on 3D computed tomography. Our experience indicates that orthognathic surgery combined with fibular osteomyocutaneous flap reconstruction can used to correct complex facial asymmetry and maxillary defects secondary to maxillectomy. Computer-assisted simulation enables precise execution of the reconstruction. It shortens the free flap ischemia time and reduces the risks associated with microsurgery.

Dental Outcomes in Computer-Assisted Orthognathic Surgery

The purpose of this study was to assess the effectiveness of computer-aided orthognathic surgery in reducing incisal overjet and establishing class I occlusion in subjects with dentofacial deformities. To address the research purpose, the investigators initiated a retrospective cohort study and enrolled a sample of subjects who underwent computer-assisted orthognathic surgery for dentofacial deformities. Two examiners assessed preoperative and postoperative lateral cephalometric radiographs for change in overjet after computer-assisted orthognathic surgery. Preoperative and postoperative occlusal photographs were then reviewed to assess for establishment of class I occlusion after computer-assisted orthognathic surgery. Cohen κ coefficient was used to assess for interrater agreement. A matched-pairs t-test was used to assess reduction in incisal overjet after computer-assisted orthognathic surgery. The sample was composed of 9 subjects who underwent computer-assisted surgery for dentofacial deformities. There was good interrater consistency for preoperative measurement of overjet (κ = 0.7, P ≤ 0.001). There was fair interrater consistency for postoperative measurement of overjet (κ = 0.4, P = 0 .02). Both examiners agreed on preoperative and postoperative assessments of occlusal photographs. There was a 3.4-mm reduction in incisal overjet after computer-assisted orthognathic surgery (P ≤ 0.001). Mean postoperative absolute overjet was 1.3 mm. In subjects with dentofacial deformities, computer-aided orthognathic surgery was effective in reducing incisal overjet and establishing class I occlusion.

Computer-assisted orthognathic surgery: feasibility study using multiple CAD/CAM surgical splints

We present a virtual planning protocol incorporating a patented 3-surgical splint technique for orthognathic surgery. The purpose of this investigation was to demonstrate the feasibility and validity of the method in vivo. The protocol consisted of (1) computed tomography (CT) or cone-beam computed tomography (CBCT) maxillofacial imaging, optical scan of articulated dental study models, segmentation, and fusion; (2) diagnosis and virtual treatment planning; (3) computed-assisted design and manufacture (CAD/CAM) of the surgical splints; and (4) intraoperative surgical transfer. Validation of the accuracy of the technique was investigated by applying the protocol to 8 adult class III patients treated with bimaxillary osteotomies. The virtual plan was compared with the postoperative surgical result using image fusion of CT/CBCT dataset by analysis of measurements between hard and soft tissue landmarks relative to reference planes. The virtual planning approach showed clinically acceptable precision for the position of the maxilla (<0.23 mm) and condyle (<0.19 mm), marginal precision for the mandible (<0.33 mm), and low precision for the soft tissue (<2.52 mm). Virtual diagnosis, planning, and use of a patented CAD/CAM surgical splint technique provides a reliable method that may offer an alternate approach to the use of arbitrary splints and 2-dimensional planning.

Three-dimensional surgical simulation

In this article, we discuss the development of methods for computer-aided jaw surgery, which allows us to incorporate the high level of precision necessary for transferring virtual plans into the operating room. We also present a complete computer-aided surgery system developed in close collaboration with surgeons. Surgery planning and simulation include construction of 3-dimensional surface models from cone-beam computed tomography, dynamic cephalometry, semiautomatic mirroring, interactive cutting of bone, and bony segment repositioning. A virtual setup can be used to manufacture positioning splints for intraoperative guidance. The system provides further intraoperative assistance with a computer display showing jaw positions and 3-dimensional positioning guides updated in real time during the surgical procedure. The computer-aided surgery system aids in dealing with complex cases with benefits for the patient, with surgical practice, and for orthodontic finishing. Advanced software tools for diagnosis and treatment planning allow preparation of detailed operative plans, osteotomy repositioning, bone reconstructions, surgical resident training, and assessing the difficulties of the surgical procedures before the surgery. Computer-aided surgery can make the elaboration of the surgical plan a more flexible process, increase the level of detail and accuracy of the plan, yield higher operative precision and control, and enhance documentation of cases.