Impact of Orthognathic Surgery on Stress Distribution in the Jaw of Class ll Women: An Integrated Analysis of Finite Element and DC/TMD.

Impact of Orthognathic Surgery on Stress Distribution in the Jaw of Class ll Women: An Integrated Analysis of Finite Element and DC/TMD. | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Impact of Orthognathic Surgery on Stress Distribution in the Jaw of Class ll Women: An Integrated Analysis of Finite Element and DC/TMD. Ricardo Sommerfeld, Bernardo Olsson, Juliana Feltrin, Luciana Signorini, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3953698/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Objectives Orthognathic surgery aims to correct dentofacial deformities to improve both function and aesthetics. However, it can affect the position of the jaw head in the mandibular fossa, impacting the temporomandibular joint (TMJ) and leading to temporomandibular dysfunction (TMD). Computational simulations using the finite element method (FEM) help measure changes that may occur in the TMJ, simulating in vivo situations. The goal of this study is to investigate the effects of orthognathic surgery on TMJ and TMD symptoms, using computational simulations and clinical analysis methods to assess changes in stress distribution in the jaw head. Materials and Methods Five women with Class II malocclusion undergoing orthognathic surgery were analyzed, with clinical and computed tomography assessments performed one week before and six months after the procedure. Results Statistical analysis showed a mean reduction in preoperative stress (723.82 ± 306.70 MPa) to postoperative stress (465.53 ± 268.27 MPa) without significance (p = 0.115). Four out of five patients did not present TMD after surgery (p = 0.250), while three out of four patients with previous articular TMD no longer had it after surgery (p = 0.500). Conclusions In conclusion, there was a trend of reduced stress in the jaw head and TMD symptoms six months after orthognathic surgery. Clinical Relevance : This study can contribute to the improvement of surgical techniques, development of postoperative follow-up protocols, and enhancement of clinical outcomes and quality of life for patients undergoing orthognathic surgery. orthognathic surgery dentofacial deformity temporomandibular dysfunction finite element analysis Figures Figure 1 Figure 2 Figure 3 Figure 4 INTRODUCTION Dentofacial deformity describes morphological anomalies involving the maxilla and mandible that are associated with varying degrees of functional alterations. Individuals with moderate-to-severe dentofacial deformities are often treated using orthognathic surgery, as these procedures are believed to improve function and quality of life. Post-surgery, enhanced masticatory performance can be observed due to stabilized dental occlusion, joint movement stability, facial harmony, and aesthetics [ 1 ]. Movements performed on the maxilla through a Le Fort I osteotomy have minimal impact on the temporomandibular joint (TMJ) because they do not involve direct trauma to the joint. However, sagittal osteotomy, a widely used technique to reposition the mandible, can trigger changes in the load distribution in the TMJ. This can lead to TMJ adaptations and, in specific cases, result in temporomandibular dysfunction (TMD) following orthognathic surgery [ 2 ]. The diagnostic evaluation of TMJ disorders requires a meticulous approach to identify, quantify, and carefully record the symptoms associated with these dysfunctions [ 3 ]. To standardize this condition, the adoption of universally accepted and validated classification criteria is crucial. In this context, the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) were proposed to enable reliable measurement of the signs and symptoms of TMD, as well as the associated psychological and psychosocial factors [ 4 ]. Furthermore, the assessment of tension in the head of the jaw is essential to enhance the understanding of the complex interactions in the TMJ. In this context, applying the Finite Element Method (FEM) offers an advanced and accurate approach for analyzing the tensions and behavior of human body structures, providing valuable insights into their function. This method uses mathematical models to study the biomechanics of anatomical structures, defining measures of tension, deformation, and displacement in the bony complex under various force-loading scenarios [ 5 ]. Thus, this study aimed to investigate, through FEM and DC/TMD, the effects of orthognathic surgery on tension distribution and signs and symptoms in the jaw heads of women with Class II malocclusion one week before surgery and six months postoperatively. MATERIALS AND METHODS This research project was approved by the Research Ethics Committee of the Health Sciences Sector of UFPR (CAAE number: 45269221.2.0000.0102). Individuals were invited to participate in the study and provided with information about the research through an Informed Consent Form. The initial sample comprised of 16 patients. Among them, 7 participants required surgeries involving the maxilla and/or chin and were excluded from the study. The remaining 9 participants were eligible for the study. However, one participant did not complete the assessment and was excluded. Additionally, 3 participants were excluded because of low resolution of the tomographic images. Ultimately, a total of five patients who required mandibular advancement were eligible for the study as illustrated in Flowchart 1. Each patient underwent evaluation one week before orthognathic surgery (T0) and at the six-month postoperative period (T1). All selected patients underwent computed tomography scans using the same device at both the T0 and T1 stages. The images were acquired using the i-CAT™ Cone Beam three-dimensional (3D) Imaging System ( Imaging Sciences International Inc ., Hatfield, PA, USA) with a field of view (FOV) of 16 × 13 cm, a resolution of 0.25 mm, 37.07 mAs, and 120 kVp, and an exposure time of 26.9 seconds. Patient positioning in the tomograph followed the standard protocol at the Imaging Teaching and Research Laboratory of UFPR (LABIM), with the Camper's plane parallel to the ground and the sagittal plane parallel to it. The generated images were in DICOM format. After acquisition, images were processed on a workstation using the i-Cat Vision™ software ( Imaging Science International , Hatfield, USA) for image reconstruction. Images were then exported to a specific 3D reconstruction program. Furthermore, during the same time frame, participants underwent an analysis of the signs and symptoms of TMD using the DC/TMD. Model Generation Geometric solids were modeled using tomographic images and manipulated in the Invesalius ™ 3.1 software (CC-GPL 2 – Brazil), as illustrated in Figure I. Segmentation was performed based on the Hounsfield number threshold principle to separate the regions of interest through tomographic images, including the cortical bone, medullary bone, dentin, and enamel. Model Preparation The 3D anatomical model and all data, including structural properties, application of muscular forces, and generation of the finite element mesh, were imported and manipulated using the Ansys Student 2019 R2 software (NASDAQ: ANSS - United States) , where the simulation was conducted. The muscles responsible for mastication include the masseter, temporalis, medial pterygoid, lateral pterygoid, and digastric muscles. The muscles involved in vertical masticatory activity (temporalis, masseter, and medial pterygoid) were used for the simulation. Based on this information, forces were applied during the simulation at the insertion of the masticatory muscles. Simulation was applied in the following manner: the temporalis muscle, average force of 235 N; masseter, average force of 151 N; and medial pterygoid, average force of 145 N (Figure II) [ 6 ]. The anatomical structures are considered to have isotropic, homogeneous, and linear elastic behaviors [ 7 ]. The Poisson's ratio and Young's modulus of cortical bone, trabecular bone, dentin, and enamel are shown in Table 1 [ 8 , 9 ]. Table 1 Material Properties. Material Young's Modulus (MPa) Poisson's Ratio Cortical Bone 13800 0.26 Trabecular Bone 345 0.38 Dentin 18600 0.31 Enamel 84100 0.2 The software discretizes the anatomical model using a finite element mesh. This mesh divides the geometry into smaller elements, allowing the analysis to be conducted separately for each element. In this analysis, a 3D tetrahedral mesh was created consisting of an average of 836,039 elements and 1,470,201 nodes. The mesh was generated automatically using Ansys Student 2019 R2 software (NASDAQ: ANSS - United States) . Simulation After the previous steps have been completed, the software is capable of automating the application of the solid mechanics equations. The program uses these equations to calculate the stresses in all elements of the mesh, considering the applied loads and material characteristics. These calculations yield a numerical scale expressing the magnitude of stress and provide a visual representation highlighting areas of higher and lower stress concentrations. Analysis of Signs and Symptoms of Temporomandibular Dysfunction (TMD) The diagnostic assessment of TMD was conducted using Axis I of the DC/TMD one week before and six months after surgery. An examiner was calibrated against the gold standard. Reproducibility was analyzed through simultaneous agreement among the three examiners. The inter-examiner reliability for the clinical evaluation associated with the validated criteria of the DC/TMD, regarding the presence or absence of TMD, was excellent (kappa ≥ 0.87). Initially, information was requested regarding the location of pain and headache in the last 30 days, which was recorded as 0 (no, pain) or 1 (yes, pain). Subsequent measurements recorded for the jaw included the standard opening pattern, opening movements (pain-free opening, unassisted maximum opening, and maximum assisted opening), lateral movements (right and left lateral), and protrusive movements. Additionally, sounds from the TMJ during opening, closing, lateral, and protrusive movements, and joint locking were recorded. The final measurement included pain experienced during palpation of the TMJ and supplementary muscles. An approximate digital pressure of 1 kg was applied to the masseter muscle (three horizontal zones: origin, body, and insertion of the masseter) and temporalis muscle (three vertical zones: anterior, middle, and posterior, as well as around the lateral joint pole); a 0.5 kg finger pressure was applied to the lateral joint pole and supplementary muscles. Palpation pressure was maintained for two seconds to determine pain, five seconds for referred pain, two seconds for muscle palpation, and five seconds for at and around the lateral joint pole. Kappa reliability testing was used to analyze the reliability of the clinical findings such as "yes" and "no" responses, pain based on muscle palpation, and joint sounds. Statistical Analysis To enhance our understanding of the collected data, descriptive and inferential analyses of the sample were conducted. Means and standard deviations were used as numerical variables for stress. The paired t-test was used to compare preoperative and postoperative values. The normal distribution of the sample data was confirmed using the Kolmogorov-Smirnov test (p > 0.05). Regarding the signs and symptoms of TMD, we conducted a descriptive analysis, categorizing cases of muscular TMD as local myalgia, myofascial pain with spread, and referred myofascial pain as 'With TMD.' The absence of pain was categorized as 'Without TMD.' For articular TMD, we investigated the presence of clicking or crepitus on the right and left sides individually and bilaterally, classifying those participants with clicking and crepitus as 'With TMD,' and those without these signs as 'Without TMD.' The McNemar test was used to compare pre and postoperative conditions. Statistical analyses were conducted using IBM SPSS version 21.0 - Statistical Package for Social Sciences , with the significance level set at 95% (p < 0.05). RESULTS Patients between 18 and 49 years of age of White ethnicity comprised the participant group. The mean preoperative stress was 723.82 ± 306.70 megapascals (MPa), which decreased to 465.53 ± 268.27 MPa after orthognathic surgery (p = 0.115) (Table 2 ). Color-coded visual representation is crucial for highlighting identified patterns. Areas of high tension are distinctly represented by warm colors such as red, whereas regions with low tension are represented by cool colors such as blue. Using this color coding allows for the quick identification of critical areas and trends in stress distribution. Our results revealed a significant predominance of stress in the posterior region of the head and mandibular neck, as shown in Figure III. Table 2 Mean and Standard Deviation in Class II and III Patients. Stress (MPA) Preoperative Postoperative P-Value Mean SD Mean SD Class II 723.83 341.52 465.53 156.02 0.115 Note: Paired t-test; Significance level of 5%. Regarding changes in the diagnoses of muscular and articular TMD after orthognathic surgery, 4 out of 5 patients who previously had muscular TMD improved and were diagnosed with the absence of TMD after surgery (p = 0.250). Similarly, in the context of articular TMD, the analysis points to a positive trend, with 3 out of 4 patients having a previous diagnosis of articular TMD who were without dysfunction after surgery (p = 0.500). The results are summarized in Table 3 . Table 3 DC/TMD Data. Angle Classification Diagnosis Pre – n (%) Post – n (%) P-Value Class II Muscular TMD Without 1 (20%) 4 (80%) 0.250 With 4 (80%) 1 (20%) Articular TMD Without 2 (40%) 4 (80%) 0.500 With 3 (60%) 1 (20%) Note: McNemar's test with a 95% confidence interval. DISCUSSION This study aimed to investigate the effects of orthognathic surgery on tension distribution in the jaw heads of women with Class II malocclusion. The results indicated that orthognathic surgery tended to reduce tension in the mandibular head, with a trending decrease in stress after the procedure. Furthermore, improvements in the diagnosis of muscular and articular TMD underscore the significance of this procedure for alleviating TMD symptoms. However, our study showed no statistically significant differences between the preoperative and postoperative data. These results can be explained by the small sample size used in this study. For FEM, considering the complexity and technical requirements inherent in such simulations is crucial. Developing detailed models coupled with extensive computational processing requires specialized resources and skills, along with a substantial allotted time for the completion of each simulation. The inclusion of ten simulations (pre- and postoperative) in this study reflects the methodological rigor which is of great importance in the literature. Another noteworthy aspect of this study is the complementarity between the FEM and DC/TMD. Finite element analysis allows the simulation and quantification of tension in the mandibular head and provides insights into the biomechanical changes resulting from surgery. In contrast, the DC/TMD enables a subjective assessment of improvements in patient complaints related to pain and TMD. A strength of our study was the homogeneity of the sample, which was restricted to women with Class II malocclusion who underwent mandibular advancement. This careful approach established a solid foundation for the analysis, eliminating potential confounding variables associated with different types of orthognathic surgery or specific sex characteristics. This refined approach provided more specific conclusions regarding the impact of orthognathic surgery, highlighting the interest of the current study in exclusively analyzing women with Class II malocclusion. Our department performed a previous study that revealed smaller mandibular head dimensions in women [ 10 ]. This smaller dimension, associated with factors such as morphological changes in the mandibular condyles, which are frequently present in patients with Class II malocclusion, reinforces the importance of specifically focusing on this group of patients. Additionally, women with a Class II malocclusion pattern have a predisposition to idiopathic condylar resorption, as evidenced by YANG and HWANG [ 11 ]. These insights contribute to a more comprehensive understanding of the relationship between sex and specific facial patterns, consolidating the importance of the current study in the exclusive analysis of women with Class II malocclusion. The reduction in tension in the disc, condyle, and temporal cartilage, as indicated by SHU et al. [ 12 ], consistently aligns with the decrease in tension observed in the present study after surgery. Moreover, the association between stress reduction and improvement in TMD symptoms, as discussed by SHU et al. [ 13 ], suggests that a decrease in tension in the mandibular head may correlate with clinical benefits observed in patients, reinforcing the importance of the results obtained in the current study. The conclusions of SUN et al. [ 14 ] and LI et al. [ 15 ] also support the idea that orthognathic surgery plays a vital role in reducing mechanical overload and relieving tension associated with functional alterations and painful symptoms in the jaw region, highlighting the clinical and therapeutic relevance of these findings. Another important aspect of our study was the analysis of muscular and articular TMD before and after treatment. The data obtained are similar with the findings of ABRAHAMSSON [ 16 ] and ABRAHAMSSON et al. [ 17 ], who showed that orthognathic surgery promotes positive patient outcomes, improving TMD signs and symptoms. The improvement in this condition after six months of treatment suggests that orthognathic surgery can be considered an effective option for treating these dysfunctions in patients with Class II malocclusion. The literature also addresses controversial results regarding the effects of surgery on TMJ health. While BERMELL et al. [ 18 ] observed that orthognathic surgery was associated with fewer TMDs, other studies, such as that by MORAISSI et al. [ 19 ], found no significant differences in TMD after surgery. These discrepancies emphasize the importance of considering individual patient factors and the need to investigate the specific effects of each surgical procedure. In summary, the results of previous studies and the present study provide valuable data on the effects of orthognathic surgery on joint tension in patients with Class II malocclusions. Nevertheless, the limitations of the present study must be considered when interpreting the results. The sample size used for the statistical analysis was small. However, to our knowledge, our sample size represents one of the largest samples ever described in the literature concerning computational simulations. Additionally, the six-month follow-up duration may not have been sufficient to capture all the changes resulting from orthosurgical treatment. Further research is required to enhance the understanding of the biomechanical impacts of different orthognathic surgeries on the TMJ and their effects on TMD symptoms, thereby enabling more personalized and effective treatment approaches for patients with dentofacial deformities. Another limitation is the absence of mandibular volume measurements. Assessment of the mandibular volume could assist in a detailed understanding of the structural modifications resulting from orthognathic surgery, particularly regarding the distribution of tension in the TMJ. To broaden and enhance our understanding of the long-term effects of orthognathic surgery, future studies with larger sample sizes and extended patient follow-ups are required. Using a larger sample would allow for a more comprehensive understanding of the effects of orthognathic surgery, enabling a more precise assessment of changes over time and ensuring the stability of surgical outcomes. This, in turn, would contribute to improving clinical practice and the therapeutic outcomes for patients. CONCLUSION The results, as indicated by the FEM, suggest that orthognathic surgery tends to reduce tension in the mandibular head six months postoperatively. The decrease in postoperative tension implies an improvement in the biomechanical stability of the region, indicating the benefits of this surgical procedure for managing mandibular tension imbalance. Regarding muscular and articular TMD, our findings suggest a positive trend towards symptom reduction six months after orthognathic surgery, although statistical significance was not achieved. DECLARATIONS Author Contribution The study in question benefited from the notable contribution of a multidisciplinary team, led by the lead author, Ricardo Sommerfeld. Sommerfeld played a central role in conducting and coordinating all phases of the research, from the study design to the analysis and interpretation of results. Additionally, his expertise was crucial in drafting the article. Juliana Feltrin played a crucial role in the statistical analysis of the collected data, providing a robust foundation for the study's conclusions. Bernardo Olsson and Luciana Signorini conducted clinical examinations on patients, ensuring the quality and accuracy of clinical data essential for the study. Aline Monise Sebastiani contributed with a finite element analysis, providing valuable insights into the biomechanical aspects addressed in the article. Her expertise was crucial for a deeper understanding of the physical and mechanical properties involved in the research. Rafaela Scariot took on the role of co-supervisor, offering academic guidance and contributing to the critical review of the article, ensuring its quality and compliance with academic standards. Delson João da Costa acted as the research supervisor, overseeing the project and contributing to the methodological integrity of the research. The effective collaboration among these professionals resulted in a comprehensive and robust work, highlighting the importance of their distinct contributions to the advancement of knowledge in the field. Ethics Approval and Consent to Participate This study involved human participants; however, we solely utilized data from clinical findings without the use of personal information or individual images. Additionally, we obtained approval from the Research Ethics Committee of the Health Sciences Sector of UFPR (CAAE Number: 45269221.2.0000.0102). Individuals were invited to participate in the study and received information through an Informed Consent Form. Funding No funding was obtained for this study. Conflict of Interests We have no conflicts of interest to disclose about financial support, corporate involvement, patent holdings, etc. REFERENCES Ravelo V, Olate G, De Moraes M, Huentequeo C, Sacco R, Olate S. Condylar Positional Changes in Skeletal Class II and Class III Malocclusions after Bimaxillary Orthognathic Surgery. J. Pers. Med., 11:1544, 2023. Shu JH, Yao J, Zhang YL, Chong DYR, Liu Z. The influence of bilateral sagittal split ramus osteotomy on the stress distributions in the temporomandibular joints of the patients with facial asymmetry under symmetric occlusions. Medicine (Baltimore), 25:97, 2018. Liu F, Steinkeler A. Epidemiology, diagnosis, and treatment of temporomandibular disorders. Dent Clin North Am, 3:465-479, 2013. Campos JADB, Carrascosa AC, Loffredo LCM, Faria JB. Consistência interna e reprodutibilidade da versão em português do critério de diagnóstico na pesquisa para desordens temporomandibulares (RDC/TMD - Eixo II). Rev. bras. fisioter., 11:451-459, 2007. Sommerfeld RS, Bergamaschi IP, Scariot R, Costa DJ. Evaluation of Tissue Tensions in Segmental Maxillary Osteotomies by Finite Element Analysis. J Oral Maxillofac Surg, 78:2298, 2020. Trento GS, Sommerfeld R, Onuki LT, Stringhini DJ, Rebellato NLB, Costa DJ. Análise por Elementos Finitos das Forças Mastigatórias em uma Placa de Reconstrução Mandibular. Br J Oral Maxillofac Surg,16:13-17, 2016. Stringhini DJ, Sommerfeld R, Uetanabaro LC, Leonardi DP, Araújo MR, Rebellato NLB, Costa DJ, Scariot R. Resistance and Stress Finite Element Analysis of Different Types of Fixation for Mandibular Orthognathic Surgery. Braz. Dent. J., 27:284-291, 2016. Pacheco AA, Saga AY, De Lima KF, Paese VN, Tanaka O. M: Stress Distribution Evaluation of the Periodontal Ligament in the Maxillary Canine for Retraction by Different Alveolar Corticotomy Techniques: A Three-dimensional Finite Element Analysis. J Contemp Dent Pract 17: 32-7, 2016. Poblete FAO, Noritomi PY, Coto NP, Almeida AS, Naclério-Homem MG: Análise por meio do método dos elementos finitos de um protetor bucal para atividades esportivas. RPG Rev Pós Grad 19: 159-64, 2012. Petinati MFP, Corso PFCL, Souza JF, Rebellato NLB, Scariot R, Costa DJ. Condylar process and temporomandibular disorders in orthognathic patients: cross-sectional study. RSBO, 1:18-28, 2022. Yang HJ, Hwang SJ. Bone mineral density and mandibular advancement as contributing factors for postoperative relapse after orthognathic surgery in patients with preoperative idiopathic condylar resorption: A prospective study with preliminary one-year follow-up. Oral Surg Oral Med Oral Pathol Oral Radiol., 2:112-8, 2015. Shu H, Tang Z, Wang X, Ma L. Biomechanical Effects of Numerically Optimized Orthognathic Surgery on Stress Distribution in the Temporomandibular Joint: A Three-Dimensional Finite Element Analysis. J Oral Maxillofac Surg, 5, 942-952, 2019. Shu H, Tang Z, Wang X, Ma L. Biomechanical Effects of Orthognathic Surgery on Stress Distribution in the Temporomandibular Joint: A Three-Dimensional Finite Element Analysis. J Oral Maxillofac Surg, 1:45-52, 2020. Sun Y, Zhou J, Hu Y, Li Z, Li Z. Biomechanical Effects of Sagittal Split Ramus Osteotomy and Mandibular Protraction: A Three-Dimensional Finite Element Analysis. J Oral Maxillofac Surg, 12:2427-2437, 2015. Li J, Wang X, Tang Z, Huang. Biomechanical Effects of Sagittal Split Ramus Osteotomy and Mandibular Protraction: A Three-Dimensional Finite Element Analysis. J Oral Maxillofac Surg, 11:2195-2206, 2014. Abrahamsson H. Orthognathic Surgery and Temporomandibular Disorders: A Retrospective Study on the Effect of Orthognathic Surgery on Signs and Symptoms of Temporomandibular Disorders. Int J Oral Maxillofac Surg, 42:20-25, 2013. Abrahamsson H, Westergren H, Pashapour A. Orthognathic Surgery and Temporomandibular Disorders: A Retrospective Study on the Effect of Orthognathic Surgery on Signs and Symptoms of Temporomandibular Disorders. J Oral Maxillofac Surg, 70:358-364, 2012. Bermell A, Peñarrocha M, Bagán J. Temporomandibular Joint Dysfunction and Orthognathic Surgery: A Prospective Study. Int J Oral Maxillofac Surg, 44:438-445, 2015. Moraissi G, Shu H., Tang Z, Ma, L. Biomechanical Effects of Orthognathic Surgery on Stress Distribution in the Temporomandibular Joint: A Three-Dimensional Finite Element Analysis. J Oral Maxillofac Surg, 7:1440-1452, 2017. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3953698","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":273819021,"identity":"80cd2a1f-f7af-4943-bca0-3fa8224e4a7a","order_by":0,"name":"Ricardo Sommerfeld","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABEElEQVRIiWNgGAWjYDACZhDBBuPZMMgwHG8AMgwsiNWSxsDDcOYASIsEAatQtNxIALFwazFvZ374uaLMxp5f7HTi44oEGx6+m8+vbvhRIMHA396dgE2LzGE2Y8kz59ISZ87O3Wx4JiGNR/J2TtnNHqDDJM6c3YBNiwQzD4NkY9vhBIPbudskG38c5jG4nZN2gweoxUAiF5cW5p9ALfZALdt/NiT85zG4eSbt5h/8WthAtjBuANrC2JBwgMfgBvux2/htYTOzbID6RbIhIZlH8kwO220ZAwkenH7hP/z4ZgMoxKRzN35sSLCT4zt+/NnNN39s5Pjbe7FqwQZ4DMAkscpBgP0BKapHwSgYBaNg+AMAy55hLo1w0O8AAAAASUVORK5CYII=","orcid":"","institution":"Federal University of Paraná","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Ricardo","middleName":"","lastName":"Sommerfeld","suffix":""},{"id":273819022,"identity":"8562b913-be5a-4f2d-8128-f9d81be59e90","order_by":1,"name":"Bernardo Olsson","email":"","orcid":"","institution":"Federal University of Paraná","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Bernardo","middleName":"","lastName":"Olsson","suffix":""},{"id":273819023,"identity":"b5da52eb-2a68-46e7-bcfa-63bb8523aa35","order_by":2,"name":"Juliana Feltrin","email":"","orcid":"","institution":"Federal University of Paraná","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Juliana","middleName":"","lastName":"Feltrin","suffix":""},{"id":273819024,"identity":"4b142a0b-82e6-4d4c-99db-1b8769d42099","order_by":3,"name":"Luciana Signorini","email":"","orcid":"","institution":"","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Luciana","middleName":"","lastName":"Signorini","suffix":""},{"id":273819025,"identity":"ec2d9c65-8a93-4e6e-99a6-78ea3c87820e","order_by":4,"name":"Aline Monise Sebastiani","email":"","orcid":"","institution":"Federal University of Paraná","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Aline","middleName":"Monise","lastName":"Sebastiani","suffix":""},{"id":273819026,"identity":"c4bf5050-9f2d-4091-a841-53a43baf0273","order_by":5,"name":"Rafaela Scariot","email":"","orcid":"","institution":"Federal University of Paraná","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Rafaela","middleName":"","lastName":"Scariot","suffix":""},{"id":273819027,"identity":"58c4e6d7-40aa-4363-9f94-d7e904ef8591","order_by":6,"name":"Delson João da Costa","email":"","orcid":"","institution":"Federal University of Paraná","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Delson","middleName":"João da","lastName":"Costa","suffix":""}],"badges":[],"createdAt":"2024-02-13 14:21:04","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3953698/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3953698/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":51506882,"identity":"f00cdca7-0bc0-48f9-aa22-e700d520a15f","added_by":"auto","created_at":"2024-02-22 19:33:05","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":214891,"visible":true,"origin":"","legend":"\u003cp\u003eManipulation of tomographic images in the 3D reconstruction of the skull.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003ea) coronal section; b) axial section; c) sagittal section; d) three-dimensional model.\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3953698/v1/f514d36cfc978ad83bebd77a.jpg"},{"id":51506880,"identity":"d550ba8d-bc95-45f3-850e-7da747c07b4a","added_by":"auto","created_at":"2024-02-22 19:33:05","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":250573,"visible":true,"origin":"","legend":"\u003cp\u003eRegions and direction of muscular force.\u003c/p\u003e\n\u003cp\u003ea) right masseter; b) right medial pterygoid; c) right temporalis; d) left masseter; e) left medial pterygoid; f) left temporalis.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-3953698/v1/9900edac55a3f3cf729ebe36.png"},{"id":51506883,"identity":"46283f31-1757-4480-ba89-7de0233fb963","added_by":"auto","created_at":"2024-02-22 19:33:05","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":204041,"visible":true,"origin":"","legend":"\u003cp\u003ePosterior View of the Mandibular Head.\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3953698/v1/330e53481b5355d69f8b1329.jpg"},{"id":51506881,"identity":"f84d7e5f-f9a3-4ca6-9516-a0350e3eb695","added_by":"auto","created_at":"2024-02-22 19:33:05","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":383268,"visible":true,"origin":"","legend":"\u003cp\u003eFlowchart 1: Patient Selection. Source: Research Data.\u003c/p\u003e","description":"","filename":"Flowchart.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3953698/v1/bff9a49333f0d0d976e3fe2b.jpg"},{"id":54806200,"identity":"2538fbe6-61c8-4e9d-9c68-41a80f74b6bb","added_by":"auto","created_at":"2024-04-17 04:41:31","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":728609,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3953698/v1/b06efd98-c230-497a-85f5-19b5d90885b2.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Impact of Orthognathic Surgery on Stress Distribution in the Jaw of Class ll Women: An Integrated Analysis of Finite Element and DC/TMD.","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eDentofacial deformity describes morphological anomalies involving the maxilla and mandible that are associated with varying degrees of functional alterations. Individuals with moderate-to-severe dentofacial deformities are often treated using orthognathic surgery, as these procedures are believed to improve function and quality of life. Post-surgery, enhanced masticatory performance can be observed due to stabilized dental occlusion, joint movement stability, facial harmony, and aesthetics [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eMovements performed on the maxilla through a Le Fort I osteotomy have minimal impact on the temporomandibular joint (TMJ) because they do not involve direct trauma to the joint. However, sagittal osteotomy, a widely used technique to reposition the mandible, can trigger changes in the load distribution in the TMJ. This can lead to TMJ adaptations and, in specific cases, result in temporomandibular dysfunction (TMD) following orthognathic surgery [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe diagnostic evaluation of TMJ disorders requires a meticulous approach to identify, quantify, and carefully record the symptoms associated with these dysfunctions [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. To standardize this condition, the adoption of universally accepted and validated classification criteria is crucial. In this context, the \u003cem\u003eDiagnostic Criteria for Temporomandibular Disorders\u003c/em\u003e (DC/TMD) were proposed to enable reliable measurement of the signs and symptoms of TMD, as well as the associated psychological and psychosocial factors [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eFurthermore, the assessment of tension in the head of the jaw is essential to enhance the understanding of the complex interactions in the TMJ. In this context, applying the Finite Element Method (FEM) offers an advanced and accurate approach for analyzing the tensions and behavior of human body structures, providing valuable insights into their function. This method uses mathematical models to study the biomechanics of anatomical structures, defining measures of tension, deformation, and displacement in the bony complex under various force-loading scenarios [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThus, this study aimed to investigate, through FEM and DC/TMD, the effects of orthognathic surgery on tension distribution and signs and symptoms in the jaw heads of women with Class II malocclusion one week before surgery and six months postoperatively.\u003c/p\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cp\u003eThis research project was approved by the Research Ethics Committee of the Health Sciences Sector of UFPR (CAAE number: 45269221.2.0000.0102). Individuals were invited to participate in the study and provided with information about the research through an Informed Consent Form.\u003c/p\u003e\n\u003cp\u003eThe initial sample comprised of 16 patients. Among them, 7 participants required surgeries involving the maxilla and/or chin and were excluded from the study. The remaining 9 participants were eligible for the study. However, one participant did not complete the assessment and was excluded. Additionally, 3 participants were excluded because of low resolution of the tomographic images. Ultimately, a total of five patients who required mandibular advancement were eligible for the study as illustrated in Flowchart 1.\u003c/p\u003e\n\u003cp\u003eEach patient underwent evaluation one week before orthognathic surgery (T0) and at the six-month postoperative period (T1). All selected patients underwent computed tomography scans using the same device at both the T0 and T1 stages. The images were acquired using the i-CAT\u0026trade; Cone Beam three-dimensional (3D) Imaging System (\u003cem\u003eImaging Sciences International Inc\u003c/em\u003e., Hatfield, PA, USA) with a field of view (FOV) of 16 \u0026times; 13 cm, a resolution of 0.25 mm, 37.07 mAs, and 120 kVp, and an exposure time of 26.9 seconds. Patient positioning in the tomograph followed the standard protocol at the Imaging Teaching and Research Laboratory of UFPR (LABIM), with the Camper's plane parallel to the ground and the sagittal plane parallel to it. The generated images were in \u003cem\u003eDICOM\u003c/em\u003e format. After acquisition, images were processed on a workstation using the i-Cat Vision\u0026trade; software (\u003cem\u003eImaging Science International\u003c/em\u003e, Hatfield, USA) for image reconstruction. Images were then exported to a specific 3D reconstruction program.\u003c/p\u003e\n\u003cp\u003eFurthermore, during the same time frame, participants underwent an analysis of the signs and symptoms of TMD using the DC/TMD.\u003c/p\u003e\n\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n\u003ch2\u003eModel Generation\u003c/h2\u003e\n\u003cp\u003eGeometric solids were modeled using tomographic images and manipulated in the \u003cem\u003eInvesalius\u003c/em\u003e\u0026trade; 3.1 software (CC-GPL 2 \u0026ndash; Brazil), as illustrated in Figure I. Segmentation was performed based on the Hounsfield number threshold principle to separate the regions of interest through tomographic images, including the cortical bone, medullary bone, dentin, and enamel.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\n\u003ch2\u003eModel Preparation\u003c/h2\u003e\n\u003cp\u003eThe 3D anatomical model and all data, including structural properties, application of muscular forces, and generation of the finite element mesh, were imported and manipulated using the \u003cem\u003eAnsys Student 2019 R2 software (NASDAQ: ANSS - United States)\u003c/em\u003e, where the simulation was conducted.\u003c/p\u003e\n\u003cp\u003eThe muscles responsible for mastication include the masseter, temporalis, medial pterygoid, lateral pterygoid, and digastric muscles. The muscles involved in vertical masticatory activity (temporalis, masseter, and medial pterygoid) were used for the simulation. Based on this information, forces were applied during the simulation at the insertion of the masticatory muscles. Simulation was applied in the following manner: the temporalis muscle, average force of 235 N; masseter, average force of 151 N; and medial pterygoid, average force of 145 N (Figure II) [\u003cspan class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003eThe anatomical structures are considered to have isotropic, homogeneous, and linear elastic behaviors [\u003cspan class=\"CitationRef\"\u003e7\u003c/span\u003e]. The Poisson's ratio and Young's modulus of cortical bone, trabecular bone, dentin, and enamel are shown in Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e [\u003cspan class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003ctable id=\"Tab1\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eMaterial Properties.\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eMaterial\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eYoung's Modulus (MPa)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003ePoisson's Ratio\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eCortical Bone\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e13800\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e0.26\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eTrabecular Bone\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e345\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e0.38\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eDentin\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e18600\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e0.31\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eEnamel\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e84100\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e0.2\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eThe software discretizes the anatomical model using a finite element mesh. This mesh divides the geometry into smaller elements, allowing the analysis to be conducted separately for each element. In this analysis, a 3D tetrahedral mesh was created consisting of an average of 836,039 elements and 1,470,201 nodes. The mesh was generated automatically using \u003cem\u003eAnsys Student 2019 R2 software (NASDAQ: ANSS - United States)\u003c/em\u003e.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\n\u003ch2\u003eSimulation\u003c/h2\u003e\n\u003cp\u003eAfter the previous steps have been completed, the software is capable of automating the application of the solid mechanics equations. The program uses these equations to calculate the stresses in all elements of the mesh, considering the applied loads and material characteristics. These calculations yield a numerical scale expressing the magnitude of stress and provide a visual representation highlighting areas of higher and lower stress concentrations.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\n\u003ch2\u003eAnalysis of Signs and Symptoms of Temporomandibular Dysfunction (TMD)\u003c/h2\u003e\n\u003cp\u003eThe diagnostic assessment of TMD was conducted using Axis I of the DC/TMD one week before and six months after surgery. An examiner was calibrated against the gold standard. Reproducibility was analyzed through simultaneous agreement among the three examiners. The inter-examiner reliability for the clinical evaluation associated with the validated criteria of the DC/TMD, regarding the presence or absence of TMD, was excellent (kappa\u0026thinsp;\u0026ge;\u0026thinsp;0.87).\u003c/p\u003e\n\u003cp\u003eInitially, information was requested regarding the location of pain and headache in the last 30 days, which was recorded as 0 (no, pain) or 1 (yes, pain). Subsequent measurements recorded for the jaw included the standard opening pattern, opening movements (pain-free opening, unassisted maximum opening, and maximum assisted opening), lateral movements (right and left lateral), and protrusive movements. Additionally, sounds from the TMJ during opening, closing, lateral, and protrusive movements, and joint locking were recorded. The final measurement included pain experienced during palpation of the TMJ and supplementary muscles.\u003c/p\u003e\n\u003cp\u003eAn approximate digital pressure of 1 kg was applied to the masseter muscle (three horizontal zones: origin, body, and insertion of the masseter) and temporalis muscle (three vertical zones: anterior, middle, and posterior, as well as around the lateral joint pole); a 0.5 kg finger pressure was applied to the lateral joint pole and supplementary muscles. Palpation pressure was maintained for two seconds to determine pain, five seconds for referred pain, two seconds for muscle palpation, and five seconds for at and around the lateral joint pole. Kappa reliability testing was used to analyze the reliability of the clinical findings such as \"yes\" and \"no\" responses, pain based on muscle palpation, and joint sounds.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\n\u003ch2\u003eStatistical Analysis\u003c/h2\u003e\n\u003cp\u003eTo enhance our understanding of the collected data, descriptive and inferential analyses of the sample were conducted. Means and standard deviations were used as numerical variables for stress. The paired t-test was used to compare preoperative and postoperative values. The normal distribution of the sample data was confirmed using the Kolmogorov-Smirnov test (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e\n\u003cp\u003eRegarding the signs and symptoms of TMD, we conducted a descriptive analysis, categorizing cases of muscular TMD as local myalgia, myofascial pain with spread, and referred myofascial pain as 'With TMD.' The absence of pain was categorized as 'Without TMD.' For articular TMD, we investigated the presence of clicking or crepitus on the right and left sides individually and bilaterally, classifying those participants with clicking and crepitus as 'With TMD,' and those without these signs as 'Without TMD.' The McNemar test was used to compare pre and postoperative conditions.\u003c/p\u003e\n\u003cp\u003eStatistical analyses were conducted using IBM SPSS version 21.0 - \u003cem\u003eStatistical Package for Social Sciences\u003c/em\u003e, with the significance level set at 95% (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e\n\u003c/div\u003e"},{"header":"RESULTS","content":"\u003cp\u003ePatients between 18 and 49 years of age of White ethnicity comprised the participant group.\u003c/p\u003e\n\u003cp\u003eThe mean preoperative stress was 723.82\u0026thinsp;\u0026plusmn;\u0026thinsp;306.70 megapascals (MPa), which decreased to 465.53\u0026thinsp;\u0026plusmn;\u0026thinsp;268.27 MPa after orthognathic surgery (p\u0026thinsp;=\u0026thinsp;0.115) (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\n\u003cp\u003eColor-coded visual representation is crucial for highlighting identified patterns. Areas of high tension are distinctly represented by warm colors such as red, whereas regions with low tension are represented by cool colors such as blue. Using this color coding allows for the quick identification of critical areas and trends in stress distribution. Our results revealed a significant predominance of stress in the posterior region of the head and mandibular neck, as shown in Figure III.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003ctable id=\"Tab2\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eMean and Standard Deviation in Class II and III Patients.\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n\u003cth colspan=\"5\" align=\"left\"\u003e\n\u003cp\u003eStress (MPA)\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003ePreoperative\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003ePostoperative\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eP-Value\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eMean\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eSD\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eMean\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eSD\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eClass II\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e723.83\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e341.52\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e465.53\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e156.02\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.115\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003ctfoot\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"6\"\u003eNote: Paired t-test; Significance level of 5%.\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tfoot\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eRegarding changes in the diagnoses of muscular and articular TMD after orthognathic surgery, 4 out of 5 patients who previously had muscular TMD improved and were diagnosed with the absence of TMD after surgery (p\u0026thinsp;=\u0026thinsp;0.250). Similarly, in the context of articular TMD, the analysis points to a positive trend, with 3 out of 4 patients having a previous diagnosis of articular TMD who were without dysfunction after surgery (p\u0026thinsp;=\u0026thinsp;0.500). The results are summarized in Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003ctable id=\"Tab3\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eDC/TMD Data.\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eAngle Classification\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eDiagnosis\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003ePre \u0026ndash; n\u003c/p\u003e\n\u003cp\u003e(%)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003ePost \u0026ndash; n\u003c/p\u003e\n\u003cp\u003e(%)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eP-Value\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"4\" align=\"left\"\u003e\n\u003cp\u003eClass II\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eMuscular TMD\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eWithout\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e1 (20%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e4 (80%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd rowspan=\"2\" align=\"char\" char=\".\"\u003e\n\u003cp\u003e0.250\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eWith\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e4 (80%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e1 (20%)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eArticular TMD\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eWithout\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e2 (40%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e4 (80%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd rowspan=\"2\" align=\"char\" char=\".\"\u003e\n\u003cp\u003e0.500\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eWith\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e3 (60%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e1 (20%)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003ctfoot\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"6\"\u003eNote: McNemar's test with a 95% confidence interval.\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tfoot\u003e\n\u003c/table\u003e\n\u003c/div\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThis study aimed to investigate the effects of orthognathic surgery on tension distribution in the jaw heads of women with Class II malocclusion. The results indicated that orthognathic surgery tended to reduce tension in the mandibular head, with a trending decrease in stress after the procedure. Furthermore, improvements in the diagnosis of muscular and articular TMD underscore the significance of this procedure for alleviating TMD symptoms. However, our study showed no statistically significant differences between the preoperative and postoperative data. These results can be explained by the small sample size used in this study. For FEM, considering the complexity and technical requirements inherent in such simulations is crucial. Developing detailed models coupled with extensive computational processing requires specialized resources and skills, along with a substantial allotted time for the completion of each simulation. The inclusion of ten simulations (pre- and postoperative) in this study reflects the methodological rigor which is of great importance in the literature.\u003c/p\u003e \u003cp\u003eAnother noteworthy aspect of this study is the complementarity between the FEM and DC/TMD. Finite element analysis allows the simulation and quantification of tension in the mandibular head and provides insights into the biomechanical changes resulting from surgery. In contrast, the DC/TMD enables a subjective assessment of improvements in patient complaints related to pain and TMD.\u003c/p\u003e \u003cp\u003eA strength of our study was the homogeneity of the sample, which was restricted to women with Class II malocclusion who underwent mandibular advancement. This careful approach established a solid foundation for the analysis, eliminating potential confounding variables associated with different types of orthognathic surgery or specific sex characteristics. This refined approach provided more specific conclusions regarding the impact of orthognathic surgery, highlighting the interest of the current study in exclusively analyzing women with Class II malocclusion.\u003c/p\u003e \u003cp\u003eOur department performed a previous study that revealed smaller mandibular head dimensions in women [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. This smaller dimension, associated with factors such as morphological changes in the mandibular condyles, which are frequently present in patients with Class II malocclusion, reinforces the importance of specifically focusing on this group of patients. Additionally, women with a Class II malocclusion pattern have a predisposition to idiopathic condylar resorption, as evidenced by YANG and HWANG [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. These insights contribute to a more comprehensive understanding of the relationship between sex and specific facial patterns, consolidating the importance of the current study in the exclusive analysis of women with Class II malocclusion.\u003c/p\u003e \u003cp\u003eThe reduction in tension in the disc, condyle, and temporal cartilage, as indicated by SHU et al. [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], consistently aligns with the decrease in tension observed in the present study after surgery. Moreover, the association between stress reduction and improvement in TMD symptoms, as discussed by SHU et al. [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e], suggests that a decrease in tension in the mandibular head may correlate with clinical benefits observed in patients, reinforcing the importance of the results obtained in the current study. The conclusions of SUN et al. [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] and LI et al. [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] also support the idea that orthognathic surgery plays a vital role in reducing mechanical overload and relieving tension associated with functional alterations and painful symptoms in the jaw region, highlighting the clinical and therapeutic relevance of these findings.\u003c/p\u003e \u003cp\u003eAnother important aspect of our study was the analysis of muscular and articular TMD before and after treatment. The data obtained are similar with the findings of ABRAHAMSSON [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e] and ABRAHAMSSON et al. [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], who showed that orthognathic surgery promotes positive patient outcomes, improving TMD signs and symptoms. The improvement in this condition after six months of treatment suggests that orthognathic surgery can be considered an effective option for treating these dysfunctions in patients with Class II malocclusion. The literature also addresses controversial results regarding the effects of surgery on TMJ health. While BERMELL et al. [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] observed that orthognathic surgery was associated with fewer TMDs, other studies, such as that by MORAISSI et al. [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], found no significant differences in TMD after surgery. These discrepancies emphasize the importance of considering individual patient factors and the need to investigate the specific effects of each surgical procedure.\u003c/p\u003e \u003cp\u003eIn summary, the results of previous studies and the present study provide valuable data on the effects of orthognathic surgery on joint tension in patients with Class II malocclusions. Nevertheless, the limitations of the present study must be considered when interpreting the results. The sample size used for the statistical analysis was small. However, to our knowledge, our sample size represents one of the largest samples ever described in the literature concerning computational simulations. Additionally, the six-month follow-up duration may not have been sufficient to capture all the changes resulting from orthosurgical treatment. Further research is required to enhance the understanding of the biomechanical impacts of different orthognathic surgeries on the TMJ and their effects on TMD symptoms, thereby enabling more personalized and effective treatment approaches for patients with dentofacial deformities. Another limitation is the absence of mandibular volume measurements. Assessment of the mandibular volume could assist in a detailed understanding of the structural modifications resulting from orthognathic surgery, particularly regarding the distribution of tension in the TMJ.\u003c/p\u003e \u003cp\u003eTo broaden and enhance our understanding of the long-term effects of orthognathic surgery, future studies with larger sample sizes and extended patient follow-ups are required. Using a larger sample would allow for a more comprehensive understanding of the effects of orthognathic surgery, enabling a more precise assessment of changes over time and ensuring the stability of surgical outcomes. This, in turn, would contribute to improving clinical practice and the therapeutic outcomes for patients.\u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eThe results, as indicated by the FEM, suggest that orthognathic surgery tends to reduce tension in the mandibular head six months postoperatively. The decrease in postoperative tension implies an improvement in the biomechanical stability of the region, indicating the benefits of this surgical procedure for managing mandibular tension imbalance.\u003c/p\u003e \u003cp\u003eRegarding muscular and articular TMD, our findings suggest a positive trend towards symptom reduction six months after orthognathic surgery, although statistical significance was not achieved.\u003c/p\u003e"},{"header":"DECLARATIONS","content":"\u003cp\u003e\u003cstrong\u003eAuthor Contribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study in question benefited from the notable contribution of a multidisciplinary team, led by the lead author, Ricardo Sommerfeld. Sommerfeld played a central role in conducting and coordinating all phases of the research, from the study design to the analysis and interpretation of results. Additionally, his expertise was crucial in drafting the article. Juliana Feltrin played a crucial role in the statistical analysis of the collected data, providing a robust foundation for the study\u0026apos;s conclusions. Bernardo Olsson and Luciana Signorini conducted clinical examinations on patients, ensuring the quality and accuracy of clinical data essential for the study. Aline Monise Sebastiani contributed with a finite element analysis, providing valuable insights into the biomechanical aspects addressed in the article. Her expertise was crucial for a deeper understanding of the physical and mechanical properties involved in the research. Rafaela Scariot took on the role of co-supervisor, offering academic guidance and contributing to the critical review of the article, ensuring its quality and compliance with academic standards. Delson Jo\u0026atilde;o da Costa acted as the research supervisor, overseeing the project and contributing to the methodological integrity of the research. The effective collaboration among these professionals resulted in a comprehensive and robust work, highlighting the importance of their distinct contributions to the advancement of knowledge in the field.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics Approval and Consent to Participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study involved human participants; however, we solely utilized data from clinical findings without the use of personal information or individual images. Additionally, we obtained approval from the Research Ethics Committee of the Health Sciences Sector of UFPR (CAAE Number: 45269221.2.0000.0102). Individuals were invited to participate in the study and received information through an Informed Consent Form.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo funding was obtained for this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of Interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe have no conflicts of interest to disclose about financial support, corporate involvement, patent holdings, etc.\u003c/p\u003e"},{"header":"REFERENCES","content":"\u003col\u003e\n\u003cli\u003eRavelo V, Olate G, De Moraes M, Huentequeo C, Sacco R, Olate S. Condylar Positional Changes in Skeletal Class II and Class III Malocclusions after Bimaxillary Orthognathic Surgery. J. Pers. Med., 11:1544, 2023.\u003c/li\u003e\n\u003cli\u003eShu JH, Yao J, Zhang YL, Chong DYR, Liu Z. The influence of bilateral sagittal split ramus osteotomy on the stress distributions in the temporomandibular joints of the patients with facial asymmetry under symmetric occlusions. Medicine (Baltimore), 25:97, 2018.\u003c/li\u003e\n\u003cli\u003eLiu F, Steinkeler A. Epidemiology, diagnosis, and treatment of temporomandibular disorders. Dent Clin North Am, 3:465-479, 2013. \u003c/li\u003e\n\u003cli\u003eCampos JADB, Carrascosa AC, Loffredo LCM, Faria JB. Consist\u0026ecirc;ncia interna e reprodutibilidade da vers\u0026atilde;o em portugu\u0026ecirc;s do crit\u0026eacute;rio de diagn\u0026oacute;stico na pesquisa para desordens temporomandibulares (RDC/TMD - Eixo II). Rev. bras. fisioter., 11:451-459, 2007.\u003c/li\u003e\n\u003cli\u003eSommerfeld RS, Bergamaschi IP, Scariot R, Costa DJ. Evaluation of Tissue Tensions in Segmental Maxillary Osteotomies by Finite Element Analysis. J Oral Maxillofac Surg, 78:2298, 2020.\u003c/li\u003e\n\u003cli\u003eTrento GS, Sommerfeld R, Onuki LT, Stringhini DJ, Rebellato NLB, Costa DJ. An\u0026aacute;lise por Elementos Finitos das For\u0026ccedil;as Mastigat\u0026oacute;rias em uma Placa de Reconstru\u0026ccedil;\u0026atilde;o Mandibular. Br J Oral Maxillofac Surg,16:13-17, 2016.\u003c/li\u003e\n\u003cli\u003eStringhini DJ, Sommerfeld R, Uetanabaro LC, Leonardi DP, Ara\u0026uacute;jo MR, Rebellato NLB, Costa DJ, Scariot R. Resistance and Stress Finite Element Analysis of Different Types of Fixation for Mandibular Orthognathic Surgery. Braz. Dent. J., 27:284-291, 2016.\u003c/li\u003e\n\u003cli\u003ePacheco AA, Saga AY, De Lima KF, Paese VN, Tanaka O. M: Stress Distribution Evaluation of the Periodontal Ligament in the Maxillary Canine for Retraction by Different Alveolar Corticotomy Techniques: A Three-dimensional Finite Element Analysis. J Contemp Dent Pract 17: 32-7, 2016. \u003c/li\u003e\n\u003cli\u003ePoblete FAO, Noritomi PY, Coto NP, Almeida AS, Nacl\u0026eacute;rio-Homem MG: An\u0026aacute;lise por meio do m\u0026eacute;todo dos elementos finitos de um protetor bucal para atividades esportivas. RPG Rev P\u0026oacute;s Grad 19: 159-64, 2012.\u003c/li\u003e\n\u003cli\u003ePetinati MFP, Corso PFCL, Souza JF, Rebellato NLB, Scariot R, Costa DJ. Condylar process and temporomandibular disorders in orthognathic patients: cross-sectional study. RSBO, 1:18-28, 2022.\u003c/li\u003e\n\u003cli\u003eYang HJ, Hwang SJ. Bone mineral density and mandibular advancement as contributing factors for postoperative relapse after orthognathic surgery in patients with preoperative idiopathic condylar resorption: A prospective study with preliminary one-year follow-up. Oral Surg Oral Med Oral Pathol Oral Radiol., 2:112-8, 2015.\u003c/li\u003e\n\u003cli\u003eShu H, Tang Z, Wang X, Ma L. Biomechanical Effects of Numerically Optimized Orthognathic Surgery on Stress Distribution in the Temporomandibular Joint: A Three-Dimensional Finite Element Analysis. J Oral Maxillofac Surg, 5, 942-952, 2019.\u003c/li\u003e\n\u003cli\u003eShu H, Tang Z, Wang X, Ma L. Biomechanical Effects of Orthognathic Surgery on Stress Distribution in the Temporomandibular Joint: A Three-Dimensional Finite Element Analysis. J Oral Maxillofac Surg, 1:45-52, 2020.\u003c/li\u003e\n\u003cli\u003eSun Y, Zhou J, Hu Y, Li Z, Li Z. Biomechanical Effects of Sagittal Split Ramus Osteotomy and Mandibular Protraction: A Three-Dimensional Finite Element Analysis. J Oral Maxillofac Surg, 12:2427-2437, 2015.\u003c/li\u003e\n\u003cli\u003eLi J, Wang X, Tang Z, Huang. Biomechanical Effects of Sagittal Split Ramus Osteotomy and Mandibular Protraction: A Three-Dimensional Finite Element Analysis. J Oral Maxillofac Surg, 11:2195-2206, 2014.\u003c/li\u003e\n\u003cli\u003eAbrahamsson H. Orthognathic Surgery and Temporomandibular Disorders: A Retrospective Study on the Effect of Orthognathic Surgery on Signs and Symptoms of Temporomandibular Disorders. Int J Oral Maxillofac Surg, 42:20-25, 2013.\u003c/li\u003e\n\u003cli\u003eAbrahamsson H, Westergren H, Pashapour A. Orthognathic Surgery and Temporomandibular Disorders: A Retrospective Study on the Effect of Orthognathic Surgery on Signs and Symptoms of Temporomandibular Disorders. J Oral Maxillofac Surg, 70:358-364, 2012.\u003c/li\u003e\n\u003cli\u003eBermell A, Pe\u0026ntilde;arrocha M, Bag\u0026aacute;n J. Temporomandibular Joint Dysfunction and Orthognathic Surgery: A Prospective Study. Int J Oral Maxillofac Surg, 44:438-445, 2015.\u003c/li\u003e\n\u003cli\u003eMoraissi G, Shu H., Tang Z, Ma, L. Biomechanical Effects of Orthognathic Surgery on Stress Distribution in the Temporomandibular Joint: A Three-Dimensional Finite Element Analysis. J Oral Maxillofac Surg, 7:1440-1452, 2017.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"orthognathic surgery, dentofacial deformity, temporomandibular dysfunction, finite element analysis","lastPublishedDoi":"10.21203/rs.3.rs-3953698/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3953698/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eObjectives\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOrthognathic surgery aims to correct dentofacial deformities to improve both function and aesthetics. However, it can affect the position of the jaw head in the mandibular fossa, impacting the temporomandibular joint (TMJ) and leading to temporomandibular dysfunction (TMD). Computational simulations using the finite element method (FEM) help measure changes that may occur in the TMJ, simulating \u003cem\u003ein vivo\u003c/em\u003e situations. The goal of this study is to investigate the effects of orthognathic surgery on TMJ and TMD symptoms, using computational simulations and clinical analysis methods to assess changes in stress distribution in the jaw head.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMaterials and Methods\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFive women with Class II malocclusion undergoing orthognathic surgery were analyzed, with clinical and computed tomography assessments performed one week before and six months after the procedure.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eStatistical analysis showed a mean reduction in preoperative stress (723.82 ± 306.70 MPa) to postoperative stress (465.53 ± 268.27 MPa) without significance (p = 0.115). Four out of five patients did not present TMD after surgery (p = 0.250), while three out of four patients with previous articular TMD no longer had it after surgery (p = 0.500).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn conclusion, there was a trend of reduced stress in the jaw head and TMD symptoms six months after orthognathic surgery.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical Relevance\u003c/strong\u003e: This study can contribute to the improvement of surgical techniques, development of postoperative follow-up protocols, and enhancement of clinical outcomes and quality of life for patients undergoing orthognathic surgery.\u003c/p\u003e","manuscriptTitle":"Impact of Orthognathic Surgery on Stress Distribution in the Jaw of Class ll Women: An Integrated Analysis of Finite Element and DC/TMD.","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-02-22 19:33:00","doi":"10.21203/rs.3.rs-3953698/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"bebcf973-dc79-402a-9104-33c7aa8882bb","owner":[],"postedDate":"February 22nd, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-04-17T04:33:25+00:00","versionOfRecord":[],"versionCreatedAt":"2024-02-22 19:33:00","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3953698","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3953698","identity":"rs-3953698","version":["v1"]},"buildId":"WrCJVZZCHTDjtuVLN7oU0","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}