Stress and Movement Trends of Maxillary Anterior Teeth During Molar Distalization with Clear Aligners Under Different Arrangement Conditions: A Finite Element Study

Stress and Movement Trends of Maxillary Anterior Teeth During Molar Distalization with Clear Aligners Under Different Arrangement Conditions: A Finite Element Study | 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 Stress and Movement Trends of Maxillary Anterior Teeth During Molar Distalization with Clear Aligners Under Different Arrangement Conditions: A Finite Element Study zhixin Li, Yuan Gao, Hui Wang, Rong Huang, Lina Ren, Liling Ren This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9468881/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 12 You are reading this latest preprint version Abstract Introduction: The aim of this study is to investigate the force distribution of the anterior teeth with the different alignment statements during the molar distalization with clear aligners. Methods A three-dimensional (3D) finite element model of maxillary molar distalization with clear aligners (CA) and four types of anterior tooth arrangement was developed. These include Group A with properly aligned incisors, Group B with anterior teeth rotation alignment, Group C with labiolingual malpositioning of anterior teeth, and group D with anterior teeth absence. Each group simulated the sequential distal movement of the maxillary second molars by 0.2mm. The study recorded the trends of 3D displacement and force distribution in the maxillary incisors during the process of molar distalization Results the total displacement of the central incisors, lateral incisors, and canines in Group B was found to be the least. The total displacement of anterior tooth was similar in Groups A and D. Interestingly, the anterior teeth of all groups demonstrated an extrusion trend, and compared to Groups A and D, the Group B and Group C showed significantly less extrusion. Additionally, the lingual surface of the crowns in the anterior teeth area of Group B experienced higher compressive stress than in the other groups. Conclusions the arrangement of the anterior teeth affects the design of anchorage during the process of molar distalization. The crowded anterior teeth can significantly enhance the "anterior anchorage" during the molar distal movement, which potentially reduce the need for supplementary anchorage devices. clear aligner molar distalization anterior teeth arrangements finite element analysis Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Background Compared with the traditional appliance, clear aligners are favored due to their aesthetics, comfort, and precision [ 1 ] . As a push appliance, several studies have demonstrated that pushing the molars backward is one of the most predictable tooth movements with clear aligners [ 2 – 5 ] . Simon et al. reported that the efficiency of molar distalization with prescribed movement of at least 1.5mm was 88% [6] . The success of the molar distalization depend on many factors, especially, adequate anchorage [ 7 – 8 ] . Therefore, to achieve more effective and precise control during the molar push-back process, Class II elastic, micro-screw implants, and other auxiliary means are often employed to minimize the anterior teeth labial inclination [ 9 – 15 ] . Many researches have focused on the the movement tendency and initial displacement of the posterior region during molar distalization, as well as the roles played by different attachments, elastic traction, or implant nails in this process [6, 19–24] . However, fewer reports are available on the alignment of anterior teeth and the force characteristics in the anterior teeth area during the molar push-back process. Finite element analysis (FEA) is a digital simulation technique used to model and analyze the responses of teeth to orthodontic forces [ 16 ] . In the field of orthodontics, FEA has been extensively used to gain a deeper understanding of tooth movement and the application of forces. Several studies have employed FEA to analyze the biomechanical characteristics of maxillary molar distalization using clear aligners, such as comparisons of different attachments and traction devices [ 16 – 18 ] . In this study, we established a three-dimensional finite element model representing a commonly encountered and representative dental arrangement of the anterior teeth in clinical practice. This model was used to simulate the process of moving the molars distally with a clear aligner, and to explore the biomechanical characteristics of the anterior teeth under the influence of clear aligner. Material and methods[16] Materials and equipment Cone beam computed tomography (CBCT) data (KaVo 3D eXamCBCT (USA), Sirona 3-in-1 CBCT (Germany)); MIMICS 21.0 software; GEOMAGIC Studio 2021; SOLIDWORK 2021; ANSYS Workbench 2024 (ANSYS, Pennsylvania, USA). Relevant statement The ethics committee of School of Stomatology, Lanzhou University, China, approved the study (LZUKQ-2023-033). The authors confirmed that all the methods were performed in accordance with the relevant guidelines and regulations. Construction of the model CBCT data (KaVo 3D eXamCBCT) were acquired class I with well-aligned dentition, no missing teeth, and healthy periodontal condition. First, the data were imported into MIMICS 21.0 software to generate three dimensional base models of the maxillary dentition. Then, we used GEOMAGIC Studio 2021 to optimize the basic model and create a surface model structure. The outer surface of the maxillary teeth roots was extended outwards by 0.25 mm to generate a preliminary model for PDL. The maxillary crown and attachment were extended outwards by 0.7 mm to simulate the thickness of the appliance, and each tooth was treated as an independent component. Finally, all components were imported into ANSYS Workbench 2024 to generate a three-dimensional finite element model for FEA. Furthermore, four groups of models were created: (1) Group A: Group with anterior teeth alignment, (2) Group B: Group with anterior teeth rotation alignment (3) Group C: Group with anterior dental misalignment (4) Group D: Missing teeth 12 and 22 in the anterior region (Fig. 1 ) "Bonded" contact was set between the roots and PDLs, as well as between the PDLs and alveolar bone. "Frictional" contact was set between the external surface of the clinical crown and the internal surface of the CA. The friction factor was set as 0.2 based on the reported literature. The upper surface of maxilla was "fixed", restricting all degrees of freedom for the elements. With these settings, convergence of the contact calculations for the model was achieved. [ 25 ] Material properties For simulation of the involved structures, We defined the physical properties for different structures. The alveolar bone, teeth, periodontal ligament (PDL), and clear aligners were assumed to exhibit linear elastic, isotropic, and homogeneous behaviors, with their mechanical parameters derived from previous studies. Differences between cortical bone and cancellous bone, as well as differences between enamel, dentin, and cementum, were not considered. Mechanical properties were inferred from previous studies [ 18 , 24 ] (Table 1 ). Table 1 Material properties Components Young’s Modulus(Mpa) Poisson’s Ratio Alveolar bone 1370 0.30 Teeth 19, 600 0.30 PDL 0.69 0.45 CA 1, 000 0.4 Design of a 3D coordinate system A 3D coordinate system was used to define the direction of x, y and z axes in order to clearly determine the displacement value of the anterior teeth. The X-axis represented the direction of the coronal plane with the positive mesial direction ; the Y-axis represents the sagittal plane with the positive lingual direction, and the Z-axis represents the vertical plane with the positive gingival direction . Loading method In the 3D model, the added forces in clinical usage were imitated, the second molar was first moved back 0.20mm into the sagittal direction and the forces resulted in deformation of the aligner. The forces of the aligner deformation on each anterior tooth were then calculated (ANSYS Workbench 2024) [ 20 ] . Results Movement Trends in the Anterior Teeth (Figs. 2 , 3 and 5) In the mesiodistal dimension, the buccolingually malpositioned group (Group C) exhibited a pronounced distal movement trend. The well-aligned group (Group A) and the rotated group (Group B) demonstrated similar mesiodistal movement patterns, with most incisors in Group B showing the smallest initial displacement. In the labiolingual dimension, all anterior teeth across groups displayed a trend of crown movement toward the labial side, except for tooth 22 in Group C. In cases with no missing anterior teeth, most teeth in the rotated group (Group B) exhibited the smallest initial displacement. In the vertical dimension, all incisors showed an extrusion trend except for tooth 22 in Group C. The rotated group (Group B) presented the least amount of extrusion, with some teeth even exhibiting intrusive movement. Overall, during clear aligner-mediated molar distalization, the anterior teeth consistently demonstrated a labial crown tipping trend. The rotated group (Group B) showed the smallest initial displacement across all three dimensions: mesiodistal, labiolingual, and vertical.(Fig. 5) Periodontal Ligament Stress Distribution Stress was primarily concentrated near the gingival margin and on the buccolingual surfaces, while stress values on the mesiodistal surfaces were relatively low. When no anterior teeth were missing, the rotated/crowded anterior tooth group exhibited the lowest equivalent stress values in the periodontal ligament, indicating the least stress. In scenarios with a missing anterior tooth, no significant change in equivalent stress was observed in the periodontal ligament of the maxillary central incisor. (Fig. 4 ) Figure 5. Displacement tendencies of crowns and roots in maxillary anterior teeth across different groups . Discussion The distalization of maxillary molars is commonly used to treat mild and moderate skeletal Class II cases, aiming to achieve the correction from a molars Class II to a molars Class I through a non-extraction orthodontic treatment plan. [ 10 ] Simon et al. [6] found that when designed for an average distal movement of 2.7 mm, the efficiency of maxillary molar distalization was the highest (reached to 88%). The authors reported that accuracy was best when there were attachments on the teeth to assist in movement. They also emphasized the crucial role of staging in treatment predictability. However, their study focused on the movement efficiency of molars and did not consider the arrangement of anchorage teeth, especially the arrangement of anterior teeth. clear aligners use elastic resin as the force carrier and apply continuous, low-intensity orthodontic forces through conformal deformation with the tooth surface, and their force transmission efficiency is highly dependent on the consistency of tooth alignment within the dental arch. During the distalization of maxillary molars with clear aligners, based on the core principle of "action and reaction" in orthodontic biomechanics, when the aligner exerts a distal driving force on the molars through elastic deformation, an equal and opposite reactive force is inevitably generated. This reactive force is transmitted through the entire dental arch to the anterior teeth and non-target teeth in the posterior region that serve as anchorage units, forming a dynamic balance between the anchorage system and the orthodontic force [ 26 ] . The stability of the anchorage system directly determines the actual efficiency and displacement accuracy of molar distalization, while the initial alignment status of anchorage teeth, as a key anatomical variable affecting anchorage strength, requires a comprehensive analysis of its clinical value in combination with the mechanical characteristics of different orthodontic techniques. This study employed three-dimensional finite element analysis to simulate different anterior tooth alignment patterns during clear aligner-mediated molar distalization. As shown in Fig. 4 , each group exhibited distinct movement characteristics in both labiolingual and vertical dimensions. The rotated anterior teeth group (Group B) demonstrated the smallest initial displacement for each incisor compared to other groups, indicating the strongest anterior anchorage during molar distalization. Both the labiolingually malpositioned group (Group C) and well-aligned group (Group A) showed significant labial inclination of tooth 12 with substantially greater initial displacement than Group B, suggesting that labiolingual malpositioning fails to enhance and may even deplete anterior anchorage . During clear aligner-mediated molar distalization, reactive forces typically induce undesirable labial inclination of anterior teeth. Stronger anterior anchorage results in greater distal movement trend of second molars, which suggested that increasing anchorage can improve the efficiency of molar distalization. As illustrated in Fig. 1 , Group B (rotated anterior teeth) exhibited the greatest initial distal displacement of second molars, while the missing anterior teeth group showed significantly less movement trend than that of the other groups. These findings further confirm that rotated anterior tooth alignment enhances anterior anchorage effectiveness. In the vertical dimension, most anterior teeth exhibited extrusion, consistent with clinical observations of anchorage loss. The rotated group (Group B) showed minimal vertical displacement, with some teeth even intruding, suggesting that initial rotation or crowding may enhance vertical anchorage under effective aligner control, which is clinically relevant for overbite management. In the mesiodistal dimension, the buccolingually malpositioned group (Group C) demonstrated pronounced distal movement, while the well-aligned (Group A) and rotated (Group B) groups displayed similar but smaller displacements. This likely results from the deviation of Group C teeth from the normal arch curvature, leading to a greater distal force component. Clinically, additional anchorage measures, such as optimized attachments or micro-implants, should be considered for severely malpositioned anterior teeth during molar distalization to prevent unwanted movement. Regarding canines, their displacement did not show significant group-specific trends in this study, likely due to their unique anatomical and biomechanical characteristics. Notably, the atypical displacement of tooth 22 in Group C—such as lack of extrusion and atypical labiolingual movement—appears related to its smaller crown size and the absence of additional attachments in this experimental setup. This highlights the need for enhanced aligner retention, possibly through optimized attachments, when moving teeth with smaller clinical crowns to ensure predictable control. Considering that orthodontic treatment primarily relies on tooth movement, more anchorage control is required. [ 27 ] In clinical, we need to consider the anchorage issue thoroughly to achieve a higher efficiency of molar distal movement. Our research suggests that when the anterior teeth are crowded due to twisting, it may not be necessary to use additional appliance such as mini-implant to reinforce the anchorage during the process of pushing molars back, as the anterior region already has strong anchorage [ 28 ] . To minimize experimental variables, this study did not incorporate attachments and consider the occlusal contacts between maxillary and mandibular dentitions. However, in clinical practice, attachments are commonly used to enhance appliance control for better management of posterior tooth movement and anterior torque. Occlusal contacts may significantly alter the anterior tooth loading pattern, thereby affecting anchorage efficacy. Future studies incorporating attachments in both posterior and anterior regions could provide more clinically relevant simulations of anterior tooth effects during clear aligner-mediated molar distalization. This study specifically demonstrates that rotated anterior teeth configuration enhances "anterior anchorage." The potential differential effects of various rotation angles warrant further investigation. Subsequent studies should simulate additional clinical scenarios to enhance the generalizability of conclusions. Besides, Randomized clinical trials would be valuable to further validate these findings. Conclusions 1. Compared to well-aligned anterior teeth, anterior teeth with labiolingual malpositioning, and missing anterior teeth, rotated anterior teeth demonstrated the least labial inclination tendency and initial displacement during molar distalization, along with a significantly reduced extrusion tendency. 2. During clear aligner-mediated molar distalization, rotated anterior teeth effectively enhance "anterior anchorage" potential. Declarations Ethics approval and consent to participate This study was approved by the Institutional Review Board of the School of Stomatology, Lanzhou University (approval number: LZUKQ-2024-62). The finite element model was constructed based on computed tomography (CT) data obtained from a healthy volunteer, who provided written informed consent prior to participation. Consent for publication The volunteer whose CT data were used in this study has provided written informed consent for the publication of this study and any accompanying anonymized images. No individual person’s data are presented in this manuscript. Availability of data and material The datasets generated and/or analyzed during the current study are available from the corresponding author upon reasonable request. Funding Not applicable References Weir T. Clear aligners in orthodontic treatment. 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Cite Share Download PDF Status: Under Revision Version 1 posted Editorial decision: Revision requested 05 May, 2026 Reviews received at journal 01 May, 2026 Reviewers agreed at journal 29 Apr, 2026 Reviewers agreed at journal 29 Apr, 2026 Reviews received at journal 28 Apr, 2026 Reviewers agreed at journal 21 Apr, 2026 Reviewers agreed at journal 21 Apr, 2026 Reviewers invited by journal 21 Apr, 2026 Editor invited by journal 21 Apr, 2026 Editor assigned by journal 20 Apr, 2026 Submission checks completed at journal 20 Apr, 2026 First submitted to journal 20 Apr, 2026 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. 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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-9468881","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":632087095,"identity":"19f1309d-81d3-4a51-83e3-3d97fb5bcdb3","order_by":0,"name":"zhixin Li","email":"","orcid":"","institution":"Lanzhou University","correspondingAuthor":false,"prefix":"","firstName":"zhixin","middleName":"","lastName":"Li","suffix":""},{"id":632087096,"identity":"a3161570-6ce6-4559-8cf3-65ea47755564","order_by":1,"name":"Yuan Gao","email":"","orcid":"","institution":"Lanzhou 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views.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-9468881/v1/2990b1bed5194b2cfd1a1522.png"},{"id":108202794,"identity":"7a38fa73-df23-4f2f-945f-7b361e235418","added_by":"auto","created_at":"2026-04-30 12:21:08","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":4214656,"visible":true,"origin":"","legend":"\u003cp\u003eThe displacement tendencies of the anterior from different groups.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-9468881/v1/aea5062651f83c13c8ee7753.png"},{"id":108491202,"identity":"a1ce6d5c-c57b-4457-a0c9-645652fd60d4","added_by":"auto","created_at":"2026-05-05 09:52:52","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":264973,"visible":true,"origin":"","legend":"\u003cp\u003eEquivalent Stress distribution in the maxillary Periodontal ligament with clear aligners\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-9468881/v1/cc5e9f73d7072fae88aefd9c.png"},{"id":108202795,"identity":"f38e91ff-f0ec-4411-bfca-5523e3149105","added_by":"auto","created_at":"2026-04-30 12:21:08","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":594919,"visible":true,"origin":"","legend":"\u003cp\u003eDisplacement tendencies of crowns and roots in maxillary anterior teeth across different groups\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-9468881/v1/ee7c07e73779d844726b0dbe.png"},{"id":109067642,"identity":"1974beed-06b7-4228-812f-22078300d090","added_by":"auto","created_at":"2026-05-12 09:58:43","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":9266038,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9468881/v1/0ba16ba4-f103-4249-ae53-834b709be80d.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Stress and Movement Trends of Maxillary Anterior Teeth During Molar Distalization with Clear Aligners Under Different Arrangement Conditions: A Finite Element Study","fulltext":[{"header":"Background","content":"\u003cp\u003eCompared with the traditional appliance, clear aligners are favored due to their aesthetics, comfort, and precision \u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/sup\u003e. As a push appliance, several studies have demonstrated that pushing the molars backward is one of the most predictable tooth movements with clear aligners \u003csup\u003e[\u003cspan additionalcitationids=\"CR3 CR4\" citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e. Simon et al. reported that the efficiency of molar distalization with prescribed movement of at least 1.5mm was 88%\u003csup\u003e[6]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe success of the molar distalization depend on many factors, especially, adequate anchorage\u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e. Therefore, to achieve more effective and precise control during the molar push-back process, Class II elastic, micro-screw implants, and other auxiliary means are often employed to minimize the anterior teeth labial inclination\u003csup\u003e[\u003cspan additionalcitationids=\"CR10 CR11 CR12 CR13 CR14\" citationid=\"CR8\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/sup\u003e. Many researches have focused on the the movement tendency and initial displacement of the posterior region during molar distalization, as well as the roles played by different attachments, elastic traction, or implant nails in this process \u003csup\u003e[6, 19\u0026ndash;24]\u003c/sup\u003e. However, fewer reports are available on the alignment of anterior teeth and the force characteristics in the anterior teeth area during the molar push-back process.\u003c/p\u003e \u003cp\u003eFinite element analysis (FEA) is a digital simulation technique used to model and analyze the responses of teeth to orthodontic forces\u003csup\u003e[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e. In the field of orthodontics, FEA has been extensively used to gain a deeper understanding of tooth movement and the application of forces. Several studies have employed FEA to analyze the biomechanical characteristics of maxillary molar distalization using clear aligners, such as comparisons of different attachments and traction devices \u003csup\u003e[\u003cspan additionalcitationids=\"CR17\" citationid=\"CR15\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e. In this study, we established a three-dimensional finite element model representing a commonly encountered and representative dental arrangement of the anterior teeth in clinical practice. This model was used to simulate the process of moving the molars distally with a clear aligner, and to explore the biomechanical characteristics of the anterior teeth under the influence of clear aligner.\u003c/p\u003e"},{"header":"Material and methods[16]","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eMaterials and equipment\u003c/h2\u003e \u003cp\u003eCone beam computed tomography (CBCT) data (KaVo 3D eXamCBCT (USA), Sirona 3-in-1 CBCT (Germany)); MIMICS 21.0 software; GEOMAGIC Studio 2021; SOLIDWORK 2021; ANSYS Workbench 2024 (ANSYS, Pennsylvania, USA).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eRelevant statement\u003c/h3\u003e\n\u003cp\u003eThe ethics committee of School of Stomatology, Lanzhou University, China, approved the study (LZUKQ-2023-033). The authors confirmed that all the methods were performed in accordance with the relevant guidelines and regulations.\u003c/p\u003e\n\u003ch3\u003eConstruction of the model\u003c/h3\u003e\n\u003cp\u003eCBCT data (KaVo 3D eXamCBCT) were acquired class I with well-aligned dentition, no missing teeth, and healthy periodontal condition. First, the data were imported into MIMICS 21.0 software to generate three dimensional base models of the maxillary dentition. Then, we used GEOMAGIC Studio 2021 to optimize the basic model and create a surface model structure. The outer surface of the maxillary teeth roots was extended outwards by 0.25 mm to generate a preliminary model for PDL. The maxillary crown and attachment were extended outwards by 0.7 mm to simulate the thickness of the appliance, and each tooth was treated as an independent component. Finally, all components were imported into ANSYS Workbench 2024 to generate a three-dimensional finite element model for FEA. Furthermore, four groups of models were created: (1) Group A: Group with anterior teeth alignment, (2) Group B: Group with anterior teeth rotation alignment (3) Group C: Group with anterior dental misalignment (4) Group D: Missing teeth 12 and 22 in the anterior region (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e)\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e\"Bonded\" contact was set between the roots and PDLs, as well as between the PDLs and alveolar bone. \"Frictional\" contact was set between the external surface of the clinical crown and the internal surface of the CA. The friction factor was set as 0.2 based on the reported literature. The upper surface of maxilla was \"fixed\", restricting all degrees of freedom for the elements. With these settings, convergence of the contact calculations for the model was achieved. \u003csup\u003e[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e25\u003c/span\u003e]\u003c/sup\u003e\u003c/p\u003e\n\u003ch3\u003eMaterial properties\u003c/h3\u003e\n\u003cp\u003eFor simulation of the involved structures, We defined the physical properties for different structures. The alveolar bone, teeth, periodontal ligament (PDL), and clear aligners were assumed to exhibit linear elastic, isotropic, and homogeneous behaviors, with their mechanical parameters derived from previous studies. Differences between cortical bone and cancellous bone, as well as differences between enamel, dentin, and cementum, were not considered. Mechanical properties were inferred from previous studies\u003csup\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e24\u003c/span\u003e]\u003c/sup\u003e (Table \u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMaterial properties\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComponents\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYoung\u0026rsquo;s Modulus(Mpa)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePoisson\u0026rsquo;s Ratio\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAlveolar bone\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1370\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTeeth\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e19, 600\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePDL\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.69\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.45\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1, 000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\n\u003ch3\u003eDesign of a 3D coordinate system\u003c/h3\u003e\n\u003cp\u003eA 3D coordinate system was used to define the direction of x, y and z axes in order to clearly determine the displacement value of the anterior teeth. The X-axis represented the direction of the coronal plane with the positive mesial direction ; the Y-axis represents the sagittal plane with the positive lingual direction, and the Z-axis represents the vertical plane with the positive gingival direction .\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eLoading method\u003c/h2\u003e \u003cp\u003eIn the 3D model, the added forces in clinical usage were imitated, the second molar was first moved back 0.20mm into the sagittal direction and the forces resulted in deformation of the aligner. The forces of the aligner deformation on each anterior tooth were then calculated (ANSYS Workbench 2024) \u003csup\u003e[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e20\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eMovement Trends in the Anterior Teeth (Figs.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e and 5)\u003c/p\u003e \u003cp\u003eIn the mesiodistal dimension, the buccolingually malpositioned group (Group C) exhibited a pronounced distal movement trend. The well-aligned group (Group A) and the rotated group (Group B) demonstrated similar mesiodistal movement patterns, with most incisors in Group B showing the smallest initial displacement.\u003c/p\u003e \u003cp\u003eIn the labiolingual dimension, all anterior teeth across groups displayed a trend of crown movement toward the labial side, except for tooth 22 in Group C. In cases with no missing anterior teeth, most teeth in the rotated group (Group B) exhibited the smallest initial displacement.\u003c/p\u003e \u003cp\u003eIn the vertical dimension, all incisors showed an extrusion trend except for tooth 22 in Group C. The rotated group (Group B) presented the least amount of extrusion, with some teeth even exhibiting intrusive movement.\u003c/p\u003e \u003cp\u003eOverall, during clear aligner-mediated molar distalization, the anterior teeth consistently demonstrated a labial crown tipping trend. The rotated group (Group B) showed the smallest initial displacement across all three dimensions: mesiodistal, labiolingual, and vertical.(Fig.\u0026nbsp;5)\u003c/p\u003e \u003cp\u003ePeriodontal Ligament Stress Distribution\u003c/p\u003e \u003cp\u003eStress was primarily concentrated near the gingival margin and on the buccolingual surfaces, while stress values on the mesiodistal surfaces were relatively low. When no anterior teeth were missing, the rotated/crowded anterior tooth group exhibited the lowest equivalent stress values in the periodontal ligament, indicating the least stress. In scenarios with a missing anterior tooth, no significant change in equivalent stress was observed in the periodontal ligament of the maxillary central incisor. (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e)\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure 5. Displacement tendencies of crowns and roots in maxillary anterior teeth across different groups\u003c/p\u003e \u003cp\u003e .\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe distalization of maxillary molars is commonly used to treat mild and moderate skeletal Class II cases, aiming to achieve the correction from a molars Class II to a molars Class I through a non-extraction orthodontic treatment plan. \u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eSimon et al. \u003csup\u003e[6]\u003c/sup\u003e found that when designed for an average distal movement of 2.7 mm, the efficiency of maxillary molar distalization was the highest (reached to 88%). The authors reported that accuracy was best when there were attachments on the teeth to assist in movement. They also emphasized the crucial role of staging in treatment predictability. However, their study focused on the movement efficiency of molars and did not consider the arrangement of anchorage teeth, especially the arrangement of anterior teeth.\u003c/p\u003e \u003cp\u003eclear aligners use elastic resin as the force carrier and apply continuous, low-intensity orthodontic forces through conformal deformation with the tooth surface, and their force transmission efficiency is highly dependent on the consistency of tooth alignment within the dental arch. During the distalization of maxillary molars with clear aligners, based on the core principle of \"action and reaction\" in orthodontic biomechanics, when the aligner exerts a distal driving force on the molars through elastic deformation, an equal and opposite reactive force is inevitably generated. This reactive force is transmitted through the entire dental arch to the anterior teeth and non-target teeth in the posterior region that serve as anchorage units, forming a dynamic balance between the anchorage system and the orthodontic force \u003csup\u003e[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e26\u003c/span\u003e]\u003c/sup\u003e. The stability of the anchorage system directly determines the actual efficiency and displacement accuracy of molar distalization, while the initial alignment status of anchorage teeth, as a key anatomical variable affecting anchorage strength, requires a comprehensive analysis of its clinical value in combination with the mechanical characteristics of different orthodontic techniques.\u003c/p\u003e \u003cp\u003eThis study employed three-dimensional finite element analysis to simulate different anterior tooth alignment patterns during clear aligner-mediated molar distalization. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, each group exhibited distinct movement characteristics in both labiolingual and vertical dimensions. The rotated anterior teeth group (Group B) demonstrated the smallest initial displacement for each incisor compared to other groups, indicating the strongest anterior anchorage during molar distalization. Both the labiolingually malpositioned group (Group C) and well-aligned group (Group A) showed significant labial inclination of tooth 12 with substantially greater initial displacement than Group B, suggesting that labiolingual malpositioning fails to enhance and may even deplete anterior anchorage .\u003c/p\u003e \u003cp\u003eDuring clear aligner-mediated molar distalization, reactive forces typically induce undesirable labial inclination of anterior teeth. Stronger anterior anchorage results in greater distal movement trend of second molars, which suggested that increasing anchorage can improve the efficiency of molar distalization. As illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, Group B (rotated anterior teeth) exhibited the greatest initial distal displacement of second molars, while the missing anterior teeth group showed significantly less movement trend than that of the other groups. These findings further confirm that rotated anterior tooth alignment enhances anterior anchorage effectiveness.\u003c/p\u003e \u003cp\u003eIn the vertical dimension, most anterior teeth exhibited extrusion, consistent with clinical observations of anchorage loss. The rotated group (Group B) showed minimal vertical displacement, with some teeth even intruding, suggesting that initial rotation or crowding may enhance vertical anchorage under effective aligner control, which is clinically relevant for overbite management.\u003c/p\u003e \u003cp\u003eIn the mesiodistal dimension, the buccolingually malpositioned group (Group C) demonstrated pronounced distal movement, while the well-aligned (Group A) and rotated (Group B) groups displayed similar but smaller displacements. This likely results from the deviation of Group C teeth from the normal arch curvature, leading to a greater distal force component. Clinically, additional anchorage measures, such as optimized attachments or micro-implants, should be considered for severely malpositioned anterior teeth during molar distalization to prevent unwanted movement.\u003c/p\u003e \u003cp\u003eRegarding canines, their displacement did not show significant group-specific trends in this study, likely due to their unique anatomical and biomechanical characteristics.\u003c/p\u003e \u003cp\u003eNotably, the atypical displacement of tooth 22 in Group C\u0026mdash;such as lack of extrusion and atypical labiolingual movement\u0026mdash;appears related to its smaller crown size and the absence of additional attachments in this experimental setup. This highlights the need for enhanced aligner retention, possibly through optimized attachments, when moving teeth with smaller clinical crowns to ensure predictable control.\u003c/p\u003e \u003cp\u003eConsidering that orthodontic treatment primarily relies on tooth movement, more anchorage control is required. \u003csup\u003e[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e27\u003c/span\u003e]\u003c/sup\u003e In clinical, we need to consider the anchorage issue thoroughly to achieve a higher efficiency of molar distal movement. Our research suggests that when the anterior teeth are crowded due to twisting, it may not be necessary to use additional appliance such as mini-implant to reinforce the anchorage during the process of pushing molars back, as the anterior region already has strong anchorage\u003csup\u003e[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e28\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eTo minimize experimental variables, this study did not incorporate attachments and consider the occlusal contacts between maxillary and mandibular dentitions. However, in clinical practice, attachments are commonly used to enhance appliance control for better management of posterior tooth movement and anterior torque. Occlusal contacts may significantly alter the anterior tooth loading pattern, thereby affecting anchorage efficacy. Future studies incorporating attachments in both posterior and anterior regions could provide more clinically relevant simulations of anterior tooth effects during clear aligner-mediated molar distalization.\u003c/p\u003e \u003cp\u003eThis study specifically demonstrates that rotated anterior teeth configuration enhances \"anterior anchorage.\" The potential differential effects of various rotation angles warrant further investigation. Subsequent studies should simulate additional clinical scenarios to enhance the generalizability of conclusions. Besides, Randomized clinical trials would be valuable to further validate these findings.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003e1. Compared to well-aligned anterior teeth, anterior teeth with labiolingual malpositioning, and missing anterior teeth, rotated anterior teeth demonstrated the least labial inclination tendency and initial displacement during molar distalization, along with a significantly reduced extrusion tendency.\u003c/p\u003e\n\u003cp\u003e2. During clear aligner-mediated molar distalization, rotated anterior teeth effectively enhance \u0026quot;anterior anchorage\u0026quot; potential.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was approved by the Institutional Review Board of the School of Stomatology, Lanzhou University (approval number: LZUKQ-2024-62). The finite element model was constructed based on computed tomography (CT) data obtained from a healthy volunteer, who provided written informed consent prior to participation.\u003c/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe volunteer whose CT data were used in this study has provided written informed consent for the publication of this study and any accompanying anonymized images. No individual person\u0026rsquo;s data are presented in this manuscript.\u003c/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eAvailability of data and material\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated and/or analyzed during the current study are available from the corresponding author upon reasonable request.\u003c/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eWeir T. Clear aligners in orthodontic treatment. Aust Dent J 2017; 62:58\u0026ndash;62. \u003c/li\u003e\n\u003cli\u003eWu D, Zhao Y, Ma M, Zhang Q, Lei H, Wang Y, Li Y, Chen X. Efficacy of mandibular molar distalization by clear aligner treatment. Zhong Nan Da Xue Xue Bao Yi Xue Ban. 2021 Oct 28;46(10):1114-1121. doi: 10.11817/j.issn.1672-7347.2021.200391. \u003c/li\u003e\n\u003cli\u003eInchingolo A.M, Inchingolo A.D, Carpentiere V, Del Vecchio G, Ferrante L, Di Noia A, Palermo A, Di Venere D, Dipalma G, Inchingolo F. Predictability of Dental Distalization with Clear Aligners:A Systematic Review. Bioengineering.2023; 10: 1390.doi: 10.3390/bioengineering10121390\u003c/li\u003e\n\u003cli\u003eGalan-Lopez L., Barcia-Gonzalez J., Plasencia E. A systematic review of the accuracy and efficiency of dental movements with Invisalign(R) Korean J. Orthod. 2019; 49:140\u0026ndash;149. doi: 10.4041/kjod.2019.49.3.140.\u003c/li\u003e\n\u003cli\u003eAikaterini, Papadimitriou, Sophia,et al.Clinical effectiveness of Invisalign orthodontic treatment: a systematic review.[J].Progress in orthodontics, 2018.DOI:10.1186/s40510-018-0235-z. \u003c/li\u003e\n\u003cli\u003eSimon M, Keilig L, Schwarze J, Jung BA, Bourauel C. Treatment outcome and efficacy of an aligner technique\u0026mdash;regarding incisor torque, premolar derotation and molar distalization. BMC Oral Health. 2014; 14: 68. doi: 10.1186/1472-6831-14-68.\u003c/li\u003e\n\u003cli\u003eMao B, Tian Y, Liu D, Zhou Y, Wang S. The effect of maxillary premolar distalization with different designed clear aligners: a 4D finite element study with staging simulation. Prog Orthod. 2024 Dec 2;25(1):46. doi: 10.1186/s40510-024-00545-z.\u003c/li\u003e\n\u003cli\u003eMiao Z, Yang Y, Zhang H, Zheng C, Gao X, Zhu J, Han Y, Wang S. Anchorage loss in maxillary premolar and anterior teeth during maxillary molar distalization in clear aligner treatment. Am J Orthod Dentofacial Orthop. 2025 Jun;167(6):690-702. doi: 10.1016/j.ajodo.2025.01.010. \u003c/li\u003e\n\u003cli\u003eWang Q, Dai D, Wang J, Chen Y, Zhang C. Biomechanical analysis of effective mandibular enmasse retraction using Class II elastics with a clear aligner: a finite element study. Prog Orthod. 2022 Jul 11;23(1):23. doi: 10.1186/s40510-022-00417-4.\u003c/li\u003e\n\u003cli\u003eCheng Y, Liu X, Chen X, Li X, Fang S, Wang W, Ma Y, Jin Z. The three-dimensional displacement tendency of teeth depending on incisor torque compensation with clear aligners of different thicknesses in cases of extraction: a finite element study. BMC Oral Health. 2022 Nov 16;22(1):499. doi: 10.1186/s12903-022-02521-7.\u003c/li\u003e\n\u003cli\u003ePadmanabhan A, Khan Y, Lambate V, K U, Naveed N, Singh M, Nagi PK. Efficacy of Clear Aligners in Treating Class III Malocclusion with Mandibular Molar Distalization: A Systematic Review. Cureus. 2023 Nov 1;15(11): e48134. doi: 10.7759/cureus.48134.\u003c/li\u003e\n\u003cli\u003eCui J, Yao C, Zhang Z, et al. Maxillary molar distalization treated with clear aligners combined with mini-implants and angel button using different traction force: a finite element study. 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Evaluation of the effects of the third molar on distalization and the effects of attachments on distalization and expansion with clear aligners: Three-dimensional finite element study. Korean J Orthod. 2025 Jan 25;55(1):69-81. doi: 10.4041/kjod24.202. \u003c/li\u003e\n\u003cli\u003eZarif Najafi H, Pakshir HR, Bahraini F. Stress Distribution and Tooth Displacement Analysis of Maxillary Molar Distalization by Different Designs of Jig in a Finite Element Study. J Dent (Shiraz). 2025 Mar 1;26(1):33-47. doi: 10.30476/dentjods.2024.100556.2230.\u003c/li\u003e\n\u003cli\u003eGOMEZ J P, PE\u0026Ntilde;A F M, MART\u0026Iacute;NEZ V, et al. Initial force systems during bodily tooth movement with plastic aligners and composite attachments: A three-dimensional finite element analysis[J]. Angle Orthod, 2015, 85(3): 454-460. doi: 10.2319/050714-330.1.\u003c/li\u003e\n\u003cli\u003eHmud R, Alamri A. Evaluating the efficacy and predictability of distalization protocols for maxillary molars in Class II treatment with clear Aligners: A narrative review. Saudi Dent J. 2024 Sep;36(9):1184-1189. doi: 10.1016/j.sdentj.2024.06.019.\u003c/li\u003e\n\u003cli\u003eProffit WR, Fields HW Jr, Sarver DM. Contemporary Orthodontics. 6th ed. St. Louis: Elsevier Saunders; 2013: 452-478.\u003c/li\u003e\n\u003cli\u003eBowman SJ, Celenza F, Sparaga J, Papadopoulos MA, Ojima K, Lin JC. Creative adjuncts for clear aligners, part 1: class II treatment. J Clin Orthod. 2015;49:83\u0026ndash;94. PMID: 26106819.\u003c/li\u003e\n\u003cli\u003eLiu H, Tang Z, Gong Z, Ye C, Wu H. Evaluation of maxillary miniscrew-anchored molar distalization appliance versus clear aligners in adult with Class II malocclusion: study protocol for a randomized controlled trial. Trials. 2025 Apr 7;26(1):123. doi: 10.1186/s13063-025-08827-5.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"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":"bmc-oral-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ohea","sideBox":"Learn more about [BMC Oral Health](http://bmcoralhealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ohea/default.aspx","title":"BMC Oral Health","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"clear aligner, molar distalization, anterior teeth, arrangements, finite element analysis","lastPublishedDoi":"10.21203/rs.3.rs-9468881/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9468881/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eIntroduction:\u003c/h2\u003e \u003cp\u003eThe aim of this study is to investigate the force distribution of the anterior teeth with the different alignment statements during the molar distalization with clear aligners.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eA three-dimensional (3D) finite element model of maxillary molar distalization with clear aligners (CA) and four types of anterior tooth arrangement was developed. These include Group A with properly aligned incisors, Group B with anterior teeth rotation alignment, Group C with labiolingual malpositioning of anterior teeth, and group D with anterior teeth absence. Each group simulated the sequential distal movement of the maxillary second molars by 0.2mm. The study recorded the trends of 3D displacement and force distribution in the maxillary incisors during the process of molar distalization\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003ethe total displacement of the central incisors, lateral incisors, and canines in Group B was found to be the least. The total displacement of anterior tooth was similar in Groups A and D. Interestingly, the anterior teeth of all groups demonstrated an extrusion trend, and compared to Groups A and D, the Group B and Group C showed significantly less extrusion. Additionally, the lingual surface of the crowns in the anterior teeth area of Group B experienced higher compressive stress than in the other groups.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003ethe arrangement of the anterior teeth affects the design of anchorage during the process of molar distalization. The crowded anterior teeth can significantly enhance the \"anterior anchorage\" during the molar distal movement, which potentially reduce the need for supplementary anchorage devices.\u003c/p\u003e","manuscriptTitle":"Stress and Movement Trends of Maxillary Anterior Teeth During Molar Distalization with Clear Aligners Under Different Arrangement Conditions: A Finite Element Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-30 12:21:03","doi":"10.21203/rs.3.rs-9468881/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-05-05T06:08:21+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-01T08:35:47+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"229224770450475911917852261543828187046","date":"2026-04-29T07:22:41+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"315286910727761750749496010194137490773","date":"2026-04-29T04:49:37+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-28T15:42:09+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"274306143460317727619641342456331218110","date":"2026-04-22T02:37:38+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"261144084270923091965049404975189828542","date":"2026-04-21T23:13:11+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-21T15:10:33+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-04-21T08:52:45+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-04-21T02:46:02+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-04-21T02:45:54+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Oral Health","date":"2026-04-20T07:59:20+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-oral-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ohea","sideBox":"Learn more about [BMC Oral Health](http://bmcoralhealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ohea/default.aspx","title":"BMC Oral Health","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"1224876f-e6d3-4cef-9bff-d2f9e28b0f61","owner":[],"postedDate":"April 30th, 2026","published":true,"recentEditorialEvents":[{"type":"decision","content":"Revision requested","date":"2026-05-05T06:08:21+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-01T08:35:47+00:00","index":36,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"in-revision","subjectAreas":[],"tags":[],"updatedAt":"2026-05-05T06:25:47+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-30 12:21:03","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9468881","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9468881","identity":"rs-9468881","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}