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.