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.

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.

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).

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.

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.

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.

Three-dimensional treatment planning of orthognathic surgery in the era of virtual imaging.

PURPOSE: The aim of this report was to present an integrated 3-dimensional (3D) virtual approach toward cone-beam computed tomography-based treatment planning of orthognathic surgery in the clinical routine. MATERIALS AND METHODS: We have described the different stages of the workflow process for routine 3D virtual treatment planning of orthognathic surgery: 1) image acquisition for 3D virtual orthognathic surgery; 2) processing of acquired image data toward a 3D virtual augmented model of the patient's head; 3) 3D virtual diagnosis of the patient; 4) 3D virtual treatment planning of orthognathic surgery; 5) 3D virtual treatment planning communication; 6) 3D splint manufacturing; 7) 3D virtual treatment planning transfer to the operating room; and 8) 3D virtual treatment outcome evaluation. CONCLUSIONS: The potential benefits and actual limits of an integrated 3D virtual approach for the treatment of the patient with a maxillofacial deformity are discussed comprehensively from our experience using 3D virtual treatment planning clinically.

A cone-beam computed tomography triple scan procedure to obtain a three-dimensional augmented virtual skull model appropriate for orthognathic surgery planning.

The aim of this study was to present a new approach to acquire a three-dimensional virtual skull model appropriate for orthognathic surgery planning without the use of plaster dental models and without deformation of the facial soft-tissue mask. A "triple" cone-beam computed tomography (CBCT) scan procedure with triple voxel-based rigid registration was evaluated and validated on 10 orthognathic patients. First, the patient was scanned vertically with a wax bite wafer in place (CBCT scan No1). Second, a limited dose scan of the patient with a Triple Tray AlgiNot impression in place was carried out (CBCT scan No2). Finally, a high-resolution scan of the Triple Tray AlgiNot impression was done (CBCT scan No3). Sequential and semiautomatic triple voxel-based rigid registration (RNo1-RNo3) was performed to augment the patient's skull model with accurate occlusal and intercuspidation data (Maxilim, version 2.1.1., Medicim NV, Mechelen, Belgium). All registrations were based on the Maximisation of Mutual Information registration algorithm. Because the accuracy and stability of the voxel-based registration (RNo1) between the Triple Tray AlgiNot impression scan and the limited low-dose patient scan were not known, this particular registration step needed to be validated. The accuracy of registration was measured on a synthetic skull and showed to be highly accurate. A volume overlap of 98.1% was found for registered impression scan No1. The mean distance between registered impression scan No1 and registered impression scan No2 was 0.08 +/- 0.03 mm (range, 0.04-0.11 mm). As far as the stability of registration was concerned, successful registration with a stable optimal position was obtained with a maximum variability of less than 0.1 mm. The results of this study showed that semiautomatic sequential triple voxel-based rigid registration of the triple CBCT scans augmented the 3-D virtual skull model with detailed occlusal and intercuspidation data in a highly accurate and robust way. The method is therefore appropriate and valid for 3-D virtual orthognathic surgery planning in the clinical routine.

Accuracy and repeatability of cone-beam computed tomography (CBCT) measurements used in the determination of facial indices in the laboratory setup.

AIM: To assess the three dimensional (3D) surface accuracy of a phantom's face acquired from a cone-beam computed tomography (CBCT) scan and to determine the reliability of selected cephalometric measurements performed with Maxilim software (Medicim N.V., Mechelen, Belgium). MATERIAL AND METHODS: A mannequin head was imaged with a CBCT (I-CAT, Imaging Sciences International, Inc., Hatfield, USA). The data were used to produce 3D surface meshes (Maxilim and Mimics, Materialise N.V., Leuven, Belgium) which were compared with an optical surface scan of the head using Focus Inspection software (Metris N.V., Leuven, Belgium). The intra- and inter-observer reliability for the measurement of distances between facial landmarks with Maxilim 3D cephalometry were determined by calculating Pearson correlation coefficients and intraclass correlation (ICC). The Dahlberg formula was used to assess the method error (ME). RESULTS: (1) The maximal range of the 3D mesh deviations was 1.9 mm for Maxilim, and 1.8mm for Mimics segmentation. (2) Test-retest and inter-observer reliability were high; Pearson's correlation coefficient was 1.000 and the ICC was 0.9998. The ME of the vertical measurements was a little larger than that calculated for the width measurements. Maximum ME was 1.33 mm. CONCLUSIONS: The 3D surface accuracy of CBCT scans segmented with Maxilim and Mimics software is high. Maxilim also shows satisfactory intra- and inter-assessor reliability for measurement of distances on a rigid facial surface.

Comparison of cephalometric radiographs obtained from cone-beam computed tomography scans and conventional radiographs.

PURPOSE: We evaluated whether measurements on conventional cephalometric radiographs are comparable to measurements on cone-beam computed tomography (CBCT)-constructed cephalometric radiographs taken from human skulls. MATERIALS AND METHODS: The CBCT scans and conventional cephalometric radiographs were made using 40 dry skulls. With I-Cat Vision software (Imaging Sciences International, Inc, Hatfield, PA), a cephalometric radiograph was constructed from the CBCT scan. Standard cephalometric software was used to identify landmarks, and calculate distances and angles. The same operator identified 15 landmarks on both types of cephalometric radiographs on all images 5 times with a 1-week interval. RESULTS: Intraobserver reliability was good for all measurements. The reproducibility of measurements on cephalometric radiographs obtained from CBCT scans was better, compared with the reproducibility of those on conventional cephalometric radiographs. There was no clinically relevant difference between measurements on conventional and constructed cephalometric radiographs. CONCLUSIONS: Measurements on CBCT-constructed cephalometric radiographs are comparable to conventional cephalometric radiographs, and are therefore suitable for longitudinal research.

Morbidity related to transmandibular distraction osteogenesis for patients with developmental deformities.

INTRODUCTION: The aim of this retrospective observational case series study was to determine the morbidity of transmandibular Distraction Osteogenesis (DO) using a bone-borne distraction device to adapt the surgical protocol and improve hardware design. PATIENTS AND METHODS: The treatment of 23 consecutive, non-syndromic patients who underwent transverse mandibular DO after a midline symphyseal osteotomy with the TransMandibular Distractor (TMD ) was evaluated. The follow-up period lasted at least 1 year after the end of the contention period. Treatments were analysed according to the morphological and functional Success Criteria (SC) for Craniofacial Distraction Osteogenesis (CFDO) for patients with developmental dentofacial malformations established by the steering group of European Collaboration on Cranial Facial Anomalies (EUROCRAN). RESULTS: Appropriate distraction was obtained in 22 of the 23 patients. One patient had irreversible dentition damage, consisting of an inadvertent apical section. All other SC for CFDO were fulfilled 100% at 1 year follow-up. Seven patients suffered from short-term local infections during different phases of treatment. Two patients suffered subluxation of a central incisor that healed uneventfully. Local discomfort due to delayed union (in three patients) and trauma to the lower lip (one patient) were also observed. CONCLUSION: The main problems were high local infection rates and damage to an apex that required a root filling, as well as patient discomfort due to delayed union and/or the bulkiness of the TMD device. Based on the results of this morbidity study, modifications are recommended for both the surgical protocol and the TMD device hardware.

The use of a wax bite wafer and a double computed tomography scan procedure to obtain a three-dimensional augmented virtual skull model.

A detailed visualization of the interocclusal relationship is essential in a three-dimensional virtual planning setup for orthognathic and facial orthomorphic surgery. The purpose of this study was to introduce and evaluate the use of a wax bite wafer in combination with a double computed tomography (CT) scan procedure to augment the three-dimensional virtual model of the skull with a detailed dental surface. A total of 10 orthognathic patients were scanned after a standardized multislice CT scanning protocol with dose reduction with their wax bite wafer in place. Afterward, the impressions of the upper and lower arches and the wax bite wafer were scanned for each patient separately using a high-resolution standardized multislice CT scanning protocol. Accurate fitting of the virtual impressions on the wax bite wafer was done with surface matching using iterative closest points. Consecutively, automatic rigid point-based registration of the wax bite wafer on the patient scan was performed to implement the digital virtual dental arches into the patient's skull model (Maxilim, version 2.0; Medicim NV, St-Niklaas, Belgium). Probability error histograms showed errors of < or =0.16 mm (25% percentile), < or =0.31 mm (50% percentile), and < or =0.92 (90% percentile) for iterative closest point surface matching. The mean registration error for automatic point-based registration was 0.17 +/- 0.07 mm (range, 0.12-0.22 mm). The combination of the wax bite wafer with the double CT scan procedure allowed for the setup of an accurate three-dimensional virtual augmented model of the skull with detailed dental surface. However, from a clinical workload, data handling, and computational point of view, this method is too time-consuming to be introduced in the clinical routine.

Three-dimensional cephalometry: spiral multi-slice vs cone-beam computed tomography.

Three-dimensional (3D) craniofacial imaging techniques are becoming increasingly popular and have opened new possibilities for orthodontic assessment, treatment, and follow-up. Recently, a new 3D cephalometric method based on spiral multi-slice (MS) computed tomography (CT) was developed and validated by our research group. This innovative 3D virtual approach is a bridge between conventional cephalometry and modern craniofacial imaging techniques and provides high-quality, accurate, and reliable quantitative 3D data. The aim of this article was to describe the advantages and the disadvantages of spiral MS-CT 3D cephalometry and to discuss the potential of cone-beam CT 3D cephalometry.

A new method of 3-D cephalometry Part I: the anatomic Cartesian 3-D reference system.

The purpose of this study was to present a new innovative three-dimensional (3-D) cephalometric method. Part I deals with the set-up and validation of a voxel-based semi-automatic 3-D cephalometric reference system. The CT data (DICOM 3.0 files) of 20 control patients with normal skeletal relationships were used for this study. To investigate accuracy and reliability of the 3-D cephalometric reference system (Maxilimtrade mark, version 1.3.0) a total of 42 (14 horizontal, 14 vertical and 14 transversal) orthogonal measurements were performed on each patient twice by each of two investigators. The intra-observer measurement error was less then 0.88 mm, 0.76 mm and 0.84 mm for horizontal, vertical and transversal orthogonal measurements, respectively. The inter-observer measurement error was less as 0.78 mm, 0.86 mm and 1.26 mm for horizontal, vertical and transversal orthogonal measurements, respectively. Squared correlation coefficients showed a high intra-observer and inter-observer reliability. The presented 3-D cephalometric reference system proved to be accurate and reliable and can therefore be used for 3-D cephalometric hard and soft tissue analysis.