The Accuracy of Three-Dimensional Soft Tissue Simulation in Orthognathic Surgery-A Systematic Review.

Three-dimensional soft tissue simulation has become a popular tool in the process of virtual orthognathic surgery planning and patient-surgeon communication. To apply 3D soft tissue simulation software in routine clinical practice, both qualitative and quantitative validation of its accuracy are required. The objective of this study was to systematically review the literature on the accuracy of 3D soft tissue simulation in orthognathic surgery. The Web of Science, PubMed, Cochrane, and Embase databases were consulted for the literature search. The systematic review (SR) was conducted according to the PRISMA statement, and 40 articles fulfilled the inclusion and exclusion criteria. The Quadas-2 tool was used for the risk of bias assessment for selected studies. A mean error varying from 0.27 mm to 2.9 mm for 3D soft tissue simulations for the whole face was reported. In the studies evaluating 3D soft tissue simulation accuracy after a Le Fort I osteotomy only, the upper lip and paranasal regions were reported to have the largest error, while after an isolated bilateral sagittal split osteotomy, the largest error was reported for the lower lip and chin regions. In the studies evaluating simulation after bimaxillary osteotomy with or without genioplasty, the highest inaccuracy was reported at the level of the lips, predominantly the lower lip, chin, and, sometimes, the paranasal regions. Due to the variability in the study designs and analysis methods, a direct comparison was not possible. Therefore, based on the results of this SR, guidelines to systematize the workflow for evaluating the accuracy of 3D soft tissue simulations in orthognathic surgery in future studies are proposed.

Resistance and Stress Analysis of 3D Plate and Locking Plate Fixation in Bilateral Sagittal Split Osteotomy: A Comparative Finite Element Study.

Aim: This study evaluates the biomechanical properties of 3D plates and compares it with locking plates, in both set back and advancement models of bilateral sagittal split osteotomy (BSSO) using finite element model analysis. Design: A stereolithography model of mandibular structure was imported to hypermesh to create 3D solid finite model. A BSSO was simulated on hemimandibular model and advancement and setback simulations were carried out for a distance of 4, 6, and 8 mm each. 3D plates for the right side and locking plates for the left side were simulated for fixation. Meshing of the model was carried out. After meshing, the model was imported to Ansys V18.1 for analysis of it. Forces simulating the masticatory muscles were applied on both sides. The values for stress and resistance in the screws and plates were measured and the lowest and highest deformation regions were estimated using von Mises analysis. Results: The results suggest that the tension and resistance as measured through were better distributed in 3D plates when compared with that of locking plates; the stress concentration was shown to be higher in the locking plates and deformation resistance was greater in 3D plates. Conclusion: The application of 3D plating system has found its place in the field of maxillofacial trauma. However, its application in the field of orthognathic surgery is yet to be explored and this study encourages us to conduct in vivo studies.

The impact of CBCT-head tilting on 3D condylar segmentation reproducibility.

OBJECTIVES: To investigate whether variations in head positioning may influence the reproducibility of cone-beam CT (CBCT) three-dimensional (3D) segmented models of the mandibular condyle. METHODS: Five fresh frozen cadaver heads were scanned in four different positions: reference position (RP) and a set of three tilted alternative head positions (AP) in anteroposterior direction (AP1: 2 cm anterior translation, AP2: 5° pitch rotation, AP3: 10° pitch rotation). Surface models of mandibular condyles were constructed and compared with the condylar reference position using voxel-based registration. Descriptive statistics and a linear mixed-effects model were performed to compare condylar volumetric differences and root mean square (RMS) distance between surfaces of AP vs RP. RESULTS: The mean differences in condylar volumes of AP vs RP were 14.1 mm³ (95% CI [-79.3, 107.4]) for AP1, 1.0 mm³ (95% CI [-87.2, 89.2]) for AP2 and 0.1 mm³ (95% CI [-88.3, 88.4]) for AP3. Mean and absolute volumetric differences did not exceed earlier reported intraoperator differences of 30 mm³. The RMS distance values obtained per group were 0.12 mm (95% CI [0.05,0.20]) for AP1, 0.17 mm (95% CI [0.10, 0.22]) for AP2 and 0.17 mm for AP3 (95% CI [0.10,0.22]). The confidence intervals (CI) for RMS distance remained far below the threshold for clinical acceptability (0.5 mm). CONCLUSIONS: Within the limits of the present study, it is suggested that tilted head positions may affect the reproducibility of 3D condylar segmentation, thereby influencing outcome in repeated CBCT scanning. Nevertheless, observed differences are unlikely to have a meaningful impact on clinical patient diagnosis and management.

Effectiveness of different protocols to reduce postoperative pain following orthognathic surgery: A systematic review and meta-analysis.

Pain management in orthognathic surgery is essential to enhance recovery, reduce hospital stay, and improve the whole experience of the patient. The aim of this systematic review was to evaluate current evidence on pain management in orthognathic surgery. A systematic review of the literature was performed following PRISMA guidelines, and PubMed, EMBASE, and the Cochrane Controlled Trials Registry were searched to retrieve randomised clinical trials (RCTs) published until July 2020. RCTs that compared different pre-emptive analgesia and low-level laser therapy (LLLT) with placebo after orthognathic surgery were included. Outcome variables were pain scores and duration of surgery. The quality of evidence was rated according to Cochrane's tool for assessing risk of bias. Standardised mean difference (SMD) or mean difference (MD) was used to analyse continuous data. There was significant pain reduction within the first 48 hours after pre-emptive analgesia (very low quality evidence, SMD: -1.329; confidence interval (CI): -2.030 to -0.628; p = 0.001) and LLLT (very low quality evidence, SMD: -0.690; CI: -1.172 to -0.207; p = 0.005) versus placebo. Evidence to support pre-emptive analgesia or LLLT effectively reducing pain scores within the first postoperative 48 hours after orthognathic surgery when compared with placebo, was of low quality.

Computed tomography imaging superimposition protocols to assess outcomes in orthognathic surgery: a systematic review with comprehensive recommendations.

OBJECTIVES: A systematic review was performed to analyze the current evidence on three-dimensional (3D) computed tomography (CT) superimposition protocols used to assess dentomaxillofacial changes after orthognathic and orthofacial surgery. Accuracy, reproducibility, and efficiency were evaluated. METHODS: The search was divided into Main Search (PubMed, EMBASE, Cochrane Library, LILACS, and SciELO), Grey Literature search (Google Scholar and Open Grey), and Manual search. Thirteen studies were included. Of these, 10 reported data on accuracy, 10 on reproducibility and five on efficiency. Seven proposed or evaluated methods of voxel-based superimposition, three focused on the surface-based technique, one compared surface- and voxel-based superimposition protocols, one used the maximum mutual information algorithm, and one described a landmark-based superimposition method. Cone-beam computed tomography (CBCT) was the most common imaging technique, being used in 10 studies. RESULTS: The accuracy of most methods was high, showing mean differences smaller than voxels' dimensions, ranging between 0.05 and 1.76 mm for translational accuracy, and 0.10-1.09° for rotational accuracy. The overall reproducibility was considered good as demonstrated by the small mean error (range: 0.01-0.26 mm) and high correlation coefficients (range: 0.53-1.00). Timing to complete virtual superimposition techniques ranged between a few seconds up to 40 min. CONCLUSIONS: Voxel-based superimposition protocols presented the highest accuracy and reproducibility. Moreover, superimposition protocols that used automated processes and involved only one software were the most efficient.

Intraoperative Navigation and Cone Beam Computed Tomography for Restoring Orbital Dimensions: A Single-Center Experience.

BACKGROUND: Correction of post-traumatic orbital defects remains a challenge for the maxillofacial surgeon. We examined the added value of combined intraoperative (IO) navigation and IO cone beam computed tomography (CBCT). MATERIALS AND METHODS: A retrospective cohort study was performed in all consecutive patients requiring unilateral post-traumatic orbital surgery between January 2012 and December 2018. Patients were divided into 3 groups: IO navigation (NAV), IO-CBCT (CBCT), and IO navigation with IO-CBCT (NAV-CBCT). A detailed description of our workflow is provided. Volumetric comparison of the operated orbit to the contralateral orbit was made with Brainlab. RESULTS: Of the 81 cases, 22 patients were included (12 males/10 females) with a mean age of 51 years. Three patients were assigned to NAV, 6 to CBCT, and 13 to NAV-CBCT. The reconstructed orbital volume did not significantly differ from the contralateral orbital volume within the 3 groups. The mean difference between the contralateral and the operated orbit was 3.05 cm3, 3.72 cm3, and 1.47 cm3 for NAV, CBCT, and NAV-CBCT, respectively, where only NAV-CBCT showed a significant smaller volumetric difference in comparison to CBCT alone. Gender or age did not correlate with difference in orbital volume. Normal function and aesthetics was seen at 6 weeks postoperative in 0 of 3, 6of 6, and 6 of 13 patients of the NAV, CBCT, and NAV-CBCT, respectively. CONCLUSION: Orbital defects can be treated effectively using IO navigation. Although our data could not demonstrate a significant added value of IO-CBCT in cases where IO navigation was used based on volumetric difference alone, the combination of IO-CBCT and IO navigation seems to give the best results considering both volumetric difference and postoperative function and aesthetics. Confirmation in a prospective, randomized trial with a larger sample size is required.

The Effect of Autologous Alveolar Bone Grafting on Nasolabial Asymmetry in Unilateral Cleft Lip and Palate.

The objective of this study was to examine whether an autologous alveolar bone graft has an effect on the nasolabial asymmetry in unilateral cleft lip, alveolus, and palate. Fifteen children (mean age 7.5 ±â€Š2.4 years) with non-syndromic unilateral cleft lip and palate (CLP) were included. Non-ionizing three-dimensional images were acquired prior to and three months after the alveolar bone grafting procedure. A 2D and a landmark-independent 3D asymmetry assessment were used to detect changes of asymmetry in the nasolabial area. For the 2D assessment, a cleft and non-cleft side ratio for 4 linear nasal and 2 linear labial distances was expressed as a Coefficient of Asymmetry (CA). The 3D asymmetry assessment comprised a robust superimposition of the face with its mirror image, expressed as a root-mean-square-error (RSME) in mm. A significant decrease in the CA for the labial distance from the facial midline to the labial commissure was observed (P = 0.036). Also, the CA for the labial distance from the facial midline to the highest point of Cupid's bow increased significantly (P = 0.028). Non-significant changes were observed for the CA for the 2 nasal distances and the 2 other labial distances. No significant changes in 3D nasal asymmetry were detected (P = 0.820). Alveolar bone grafting completes the alveolar ridge but has only little to no clinical effect on the asymmetry of the secondary cleft lip nasal deformity.

Custom-made 3D-printed face masks in case of pandemic crisis situations with a lack of commercially available FFP2/3 masks.

In the case of pandemic crisis situations, a crucial lack of protective material such as protective face masks for healthcare professionals can occur. A proof of concept (PoC) and prototype are presented, demonstrating a reusable custom-made three-dimensionally (3D) printed face mask based on materials and techniques (3D imaging and 3D printing) with global availability. The individualized 3D protective face mask consists of two 3D-printed reusable polyamide composite components (a face mask and a filter membrane support) and two disposable components (a head fixation band and a filter membrane). Computer-aided design (CAD) was used to produce the reusable components of the 3D face mask based on individual facial scans, which were acquired using a new-generation smartphone with two cameras and a face scanning application. 3D modelling can easily be done by CAD designers worldwide with free download software. The disposable non-woven melt-blown filter membrane is globally available from industrial manufacturers producing FFP2/3 protective masks for painting, construction, agriculture, and the textile industry. Easily available Velcro fasteners were used as a disposable head fixation band. A cleaning and disinfection protocol is proposed. Leakage and virological testing of the reusable components of the 3D face mask, following one or several disinfection cycles, has not yet been performed and is essential prior to its use in real-life situations. This PoC should allow the reader to consider making and/or virologically testing the described custom-made 3D-printed face masks worldwide. The surface tessellation language (STL) format of the original virtual templates of the two reusable components described in this paper can be downloaded free of charge using the hyperlink (Supplementary Material online).

Validation of a 3D CBCT-based protocol for the follow-up of mandibular condyle remodeling.

OBJECTIVES: Three-dimensional models of mandibular condyles provide a way for condylar remodeling follow-up. The overall aim was to develop and validate a user-friendly workflow for cone beam CT (CBCT)-based semi-automatic condylar registration and segmentation. METHODS: A rigid voxel-based registration (VBR) technique for registration of two post-operative CBCT-scans was tested. Two modified mandibular rami, with or without gonial angle, were investigated as the volume of interest for registration. Inter- and intraoperator reproducibility of this technique was tested on 10 mandibular rami of orthognathic patients by means of intraclass correlation coefficients (ICC's) and descriptive statistics of the transformation values from the VBR. The difference in reproducibility between the two modified rami was evaluated using a paired t-test (p < 0.05). For the segmentation, eight fresh frozen cadaver heads were scanned with CBCT and micro-CT. These data were used to test the inter- and intraoperator reproducibility (ICC's) and accuracy (Bland-Altman plot) of a newly designed workflow based on semi-automated contour enhancement. RESULTS: Excellent ICC's (0.94-0.99) were obtained for the voxel-based registration technique using both modified rami. If the gonial angle was not included in the volume of interest, there was a trend of increased operator error suggested by significant higher interoperator differences in translation values (p = 0,0036). The segmentation workflow proved to be highly reproducible with excellent ICC's (0.99), low absolute mean volume differences between operators (23.19 mm3), within operators (28.93 mm3) and low surface distances between models of different operators (<0.20 mm). Regarding the accuracy, CBCT-models slightly overestimate the condylar volume compared to micro-CT. CONCLUSIONS: This study provides a validated user-friendly and reproducible method of creating three-dimensional-surface models of mandibular condyles out of longitudinal CBCT-scans.

Postoperative Respiratory Complications After Cleft Palate Closure in Patients With Pierre Robin Sequence: Operative Considerations.

BACKGROUND: In cleft palate surgery, there is currently no consensus on the management of patients with Pierre Robin Sequence (PRS). The authors aimed to evaluate the treatment strategy of cleft palate in our centers, with emphasis on patients with PRS, as the authors noted some patients with severe respiratory distress. Moreover, the authors aimed to investigate the prevalence of postoperative respiratory complications, using a modified-Furlow palatoplasty in combination with intravelar veloplasty in both patients with PRS and patients with non-PRS. METHODS: The authors retrospectively identified all consecutive patients, both PRS and non-PRS, who underwent palate repair between January 1, 2012 and December 15, 2014 at 2 cooperating cleft centers (Bruges, Belgium; Budapest, Hungary). The treatment modality was uniform and performed by the same 2 surgeons. RESULTS: In 92 consecutive patients, 4 patients experienced respiratory distress after palate repair. The female-to-male ratio was 1:1. The mean age at surgery in these 4 patients was 15 months (range 13-19 months). Fifteen percent (2/13) of patients with PRS experienced respiratory distress in comparison to 3% (2/79) of non-PRS (χ = 4.43; P = 0.035). CONCLUSIONS: This is the first report of postoperative respiratory difficulties, while using a modified-Furlow palatoplasty in combination with intravelar veloplasty. In the present author's experience, the authors suggest to perform a 2-stage closure of the cleft palate in patients with PRS and to do so at a later age, when the palatal tissues and airway structures are more mature. Moreover, patients with PRS should be monitored closely, as they can present with different degrees of respiratory distress after palatoplasty.

A Systematic Review to Uncover a Universal Protocol for Accuracy Assessment of 3-Dimensional Virtually Planned Orthognathic Surgery.

PURPOSE: The aim of this study was to systematically review methods used for assessing the accuracy of 3-dimensional virtually planned orthognathic surgery in an attempt to reach an objective assessment protocol that could be universally used. MATERIALS AND METHODS: A systematic review of the currently available literature, published until September 12, 2016, was conducted using PubMed as the primary search engine. We performed secondary searches using the Cochrane Database, clinical trial registries, Google Scholar, and Embase, as well as a bibliography search. Included articles were required to have stated clearly that 3-dimensional virtual planning was used and accuracy assessment performed, along with validation of the planning and/or assessment method. Descriptive statistics and quality assessment of included articles were performed. RESULTS: The initial search yielded 1,461 studies. Only 7 studies were included in our review. An important variability was found regarding methods used for 1) accuracy assessment of virtually planned orthognathic surgery or 2) validation of the tools used. Included studies were of moderate quality; reviewers' agreement regarding quality was calculated to be 0.5 using the Cohen κ test. CONCLUSIONS: On the basis of the findings of this review, it is evident that the literature lacks consensus regarding accuracy assessment. Hence, a protocol is suggested for accuracy assessment of virtually planned orthognathic surgery with the lowest margin of error.

Transoral Fixation of Bicortical Screws Is Safe and Feasible for Lower Jaw Osteotomies.

PURPOSE: Transoral placement of bicortical screws is a rigid fixation method in orthognathic surgery that is used less often than transbuccal placement. The aim of this study was to examine the postoperative outcome of transoral bicortical screw insertion during orthognathic surgery and to compare it with the more common transbuccal fixation technique. MATERIALS AND METHODS: A retrospective cohort study was conducted. Clinical files of orthognathic surgery patients operated on from January 2010 through December 2012 were reviewed. Screw insertion approach (transoral vs transbuccal) was examined as a predictive variable for postoperative complications (hardware removal and infection). Type of surgery, fibrin sealant, preoperative third molar removal, and patient age and gender were analyzed as potential risk factors. Descriptive and bivariate statistics and regression analyses were performed. RESULTS: Of the 606 patients whose cases were reviewed, 509 patients (185 men; mean age, 26.3 ± 11.1 yr) met the inclusion criteria. Most presented with a Class II malocclusion (84.5%). A transbuccal approach was used in 27.5% of cases, leading to a screw-related infection of 6.3%. Patients treated with a transoral technique (72.5%) had fewer infections (3.5%), but this was not statistically relevant. Screw removal was indicated in 3.3% of patients. Screw placement using the transoral and transbuccal approaches was performed in 3.0 and 4.2% of patients, respectively. Infection and screw removal rates did not differ significantly between fixation techniques (P = .16 and P = .49, respectively). CONCLUSION: The present findings showed an overall low rate of screw removal and infection secondary to bicortical screw insertion during orthognathic surgery. The postoperative outcome was similar for the transoral and transbuccal approaches.

Oral Mucosal Z-Plasty in Combination with Intravelar Veloplasty.

Our aim was to establish a reliable, functional surgical technique for soft palate closure. A step-by-step description of the operative procedure is presented. A cross-over procedure has been developed by combining the principles of a mucosal Z-plasty only on the oral side of the cleft palate, the intravelar veloplasty following Sommerlad's principles and a straight line closure on the nasal side. In the last 2 years, 25 patients have undergone the operation at the Cleft Centre of the 1st Paediatric Department of the Semmelweis University Budapest, Hungary. In all cases the operative technique could be adapted, operations were uneventful and straightforward. This technique was appropriate to close all the soft palate clefts, even the wide ones. This procedure combines the advantages of both procedures and has shown very good early postoperative results.

Presentation and Evaluation of a Modified Wax-Bite Dental Splint for Surgical Navigation in Craniomaxillofacial Surgery.

PURPOSE: The purpose of the present study was to introduce and evaluate the use of a modified "wax-bite dental splint" for surgical navigation in craniomaxillofacial surgery. MATERIALS AND METHODS: A 2-layer wax bite dental splint was fabricated with an anterior extension, and 8 gutta percha markers were incorporated in each splint for marker-based pair-point registration. To evaluate the accuracy, the occlusal registration of the wax bite dental splint was performed on 10 artificial skulls. Consecutively, all the skulls were scanned using a standardized cone-beam computed tomography scanning protocol with the 2-layer wax bite dental splint in place. Automatic rigid marker-based pair-point registration was performed using the iPlan CMF software, version 3.0 (Brainlab AG, Feldkirchen, Germany) using 8 gutta percha markers incorporated into the wax bite dental splint. Additionally, the registration accuracy of 6 anatomic skeletal landmarks was measured on each skull. RESULTS: The mean registration error for each wax bite dental splint ranged from 0.78 to 1.01 mm. The overall mean registration error for the wax-bite dental splint-based registration was 0.89 ± 0.08 mm. The mean registration error for the 6 anatomic landmarks ranged from 1.23 to 2.3 mm. The overall mean registration error was 1.68 ± 0.28 mm. CONCLUSION: The results of the present study show the potential for a wax-bite dental splint as an alternative rigid registration method for surgical navigation in craniomaxillofacial surgery. Moreover, from a clinical viewpoint, the method is accurate, user-friendly, inexpensive, and not time-consuming.

Timing of three-dimensional virtual treatment planning of orthognathic surgery: a prospective single-surgeon evaluation on 350 consecutive cases.

The purpose of this article is to evaluate the timing for three-dimensional (3D) virtual treatment planning of orthognathic surgery in the daily clinical routine. A total of 350 consecutive patients were included in this study. All patients were scanned following the standardized "Triple CBCT Scan Protocol" in centric relation. Integrated 3D virtual planning and actual surgery were performed by the same surgeon in all patients. Although clinically acceptable, still software improvements especially toward 3D virtual occlusal definition are mandatory to make 3D virtual planning of orthognathic surgery less time-consuming and more user-friendly to the clinician.

Three-dimensional simulation of the nasoalveolar cleft defect.

This study describes the planning process for a three-dimensional (3D) model of a nasoalveolar bone graft in patients with unilateral cleft lip and palate. A 3D reconstruction of the alveolar cleft based on cone-beam computed tomography was performed in 10 patients. Graft models were planned using a 3D planning software (iPlan ENT 3.0, Brainlab, Feldkirchen, Germany) and printed using a 3D printer (Objet30 Pro, Objet Ltd., Rehovot, Israel). A reproducible, step-by-step planning method was established, which is manual rather than automatic. Still, the 3D visualization and a life-size graft template could be useful during secondary alveolar osteoplasty.

Success rate of miniplate anchorage for bone anchored maxillary protraction.

OBJECTIVE: To evaluate the success rate of Bollard miniplate anchorage for bone anchored maxillary protraction (BAMP). MATERIALS AND METHODS: Twenty-five consecutive patients (mean age, 12.0 ± 1.2 years; range, 8.7-14.8 years) with maxillary hypoplasia without congenital or acquired deformation were included in this study. A total of 100 Bollard modified miniplates were placed by the same surgeon. Ninety-nine miniplates were inserted under general anesthesia, and one was placed under local anesthesia because of initially soft bone conditions. Loading of the miniplates with 150 g elastics was initiated at 17.5 ± 6.9 days (range, 11-38 days) after surgery. Mean follow-up was provided at 20.8 ± 11.1 months (range, 6.5-46.2 months). RESULTS: The overall success rate of miniplate anchorage in terms of stability was 97%. During orthodontic loading, five miniplates showed signs of mobility. After interruption of loading over 2 months, two miniplates became stable again. However, a total of three miniplates needed to be removed and were successfully replaced under local anesthesia after a mean healing period of 3 months. CONCLUSION: Skeletal anchorage by means of Bollard modified miniplates is effective for BAMP. Success depends on proper presurgical patient counseling, minimal invasive surgery, good postsurgical instructions, and orthodontic follow-up.