Preserved maxillary transverse width following bilateral premolar extraction in a skeletal Class III malocclusion: a case report

Preserved maxillary transverse width following bilateral premolar extraction in a skeletal Class III malocclusion: a case report | 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 Case Report Preserved maxillary transverse width following bilateral premolar extraction in a skeletal Class III malocclusion: a case report Yu-Hsiang Chang, Yi-Mien Cheng, Yuan-Hou Chen, Jian-Hong Yu This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8243460/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 Background Skeletal Class III malocclusion with simultaneous anterior and posterior crossbite is uncommon and often presents with combined sagittal and transverse discrepancies. Extraction-based camouflage treatment is traditionally associated with predictable reductions in maxillary transverse dimensions during space closure. However, rare cases may deviate from this pattern. This report describes a unique presentation in which maxillary intermolar width remained fully preserved following bilateral premolar extractions, highlighting an unusual transverse response with clinical relevance for treatment planning. Case presentation: 19-year-old woman presented with a concave facial profile, anterior and posterior crossbite, and dental crowding. She declined orthognathic surgery, and a non-surgical camouflage plan was adopted. Four premolars were extracted to create space for alignment and crossbite correction. The treatment sequence incorporated an inside-out technique aimed at maintaining transverse stability while assisting correction of the posterior crossbite, sectional archwire mechanics with adjunctive Class III elastics during space closure, and a wire-plus-aligner approach in the finishing phase for high-precision detailing. Throughout the 31-month treatment period, maxillary intermolar width remained unchanged, contrary to the transverse constriction commonly associated with extraction mechanics. Both anterior and posterior crossbite were corrected, and facial esthetics improved. Conclusion This case demonstrates an unusual transverse response during extraction-based camouflage treatment of skeletal Class III malocclusion, with complete preservation of maxillary intermolar width. Recognition of such variability may help clinicians better anticipate potential transverse outcomes when planning complex Class III camouflage treatment. Anterior crossbite Posterior crossbite Skeletal Class III Transverse width Premolar extraction Maxillary stability Orthodontic case report Figures Figure 1 Figure 2 Figure 3 Background Skeletal Class III malocclusion displays diverse skeletal components—including maxillary retrusion, mandibular prognathism, and transverse or vertical imbalances—reflecting its broad phenotypic spectrum [ 1 ]. Its clinical presentation often includes anterior crossbite, reduced facial convexity, and functional shifts, and its prevalence is notably higher in East Asian populations. The coexistence of both anterior and posterior crossbite represents a particularly challenging subtype, as it reflects simultaneous sagittal and transverse discrepancies. Early identification of skeletal Class III discrepancies is critical because dental compensation can obscure the true severity of the underlying skeletal imbalance, potentially influencing treatment decisions [ 2 ]. In adult patients who decline orthognathic surgery, camouflage treatment remains an important therapeutic alternative. However, extraction therapy—especially the removal of first premolars—is associated with predictable transverse effects. Little et al. and Shields et al. demonstrated that premolar extraction cases often exhibit long-term changes in mandibular anterior alignment, suggesting a susceptibility to post-retention instability [ 3 , 4 ]. In addition, Kim and Gianelly reported notable differences in arch widths and smile esthetics between extraction and non-extraction treatment modalities, indicating that tooth removal may alter transverse dental relationships and overall arch form [ 5 ]. These findings have shaped the conventional expectation that extraction mechanics inherently reduce transverse dimension in non-surgical Class III patients. Despite this, biomechanical research suggests that arch width changes are not solely determined by extraction patterns. The segmented arch technique offers a well-controlled force system, which can help clinicians minimize unintended effects during space closure, including potential changes in arch form [ 6 ]. Furthermore, differences in bracket–archwire friction can modify the efficiency and predictability of sliding mechanics during space closure, which may in turn influence the overall pattern in which tooth movement is expressed [ 7 ]. The clinical use of improved super-elastic nickel-titanium wires has been documented in case reports detailing successful orthodontic management of complex skeletal Class III malocclusions [ 8 , 9 ], supporting their role in comprehensive treatment approaches that may include controlled alignment and dental compensation. Given the scarcity of reports describing atypical transverse behavior during non-surgical Class III treatment, particularly cases showing preserved or stable arch width despite premolar extractions, further documentation is warranted. This case contributes to the understanding of biomechanical and biological variability in transverse response, highlighting the need for individualized diagnosis and careful interpretation of traditional expectations in camouflage therapy. Case Presentation A 19-year-old woman presented with concerns of unesthetic dental alignment and functional difficulty when incising food. She was medically healthy, with no craniofacial trauma, systemic conditions, or parafunctional habits. Extraoral examination revealed a concave soft-tissue profile, reduced maxillary prominence, and a mild mandibular deviation to the right. No temporomandibular disorders were noted. Intraoral examination showed an uncommon combination of both anterior and bilateral posterior crossbite. The patient presented with an anterior crossbite (overjet − 1.5 mm) and bilateral posterior crossbite. Maxillary crowding was severe, measuring − 4.0 mm on the right and − 9.0 mm on the left; mandibular crowding measured − 5.5 mm and − 4.5 mm, respectively. A supernumerary tooth was present in the anterior maxilla. Periodontal tissues were healthy. Panoramic radiography showed normal alveolar bone levels and intact root morphology. Lateral cephalometric analysis confirmed skeletal Class III malocclusion (SNA 80.0°, SNB 84.5°, ANB − 4.5°) with a mandibular plane angle of 28.0°. Mandibular incisors were retroclined due to dental compensation. Baseline maxillary intermolar width was 49.5 mm—within the upper range of normal—despite the presence of crowding and crossbite. Given the patient’s refusal of orthognathic surgery, a non-surgical camouflage plan was adopted. Because of the crowding severity and the need for both sagittal and transverse correction, extraction of all four first premolars was indicated. The treatment incorporated three key clinical strategies to manage the unusual combination of crossbite patterns: 1. Inside-out technique The inside-out technique was implemented using customized archwires with reversed insertion (inner surface facing outward). This approach provided controlled bilateral expansion force, successfully maintaining maxillary transverse dimension at 49.5 mm throughout the treatment despite extraction therapy. (Fig. 1 ) 2. Sectional archwire mechanics with adjunctive Class III elastics Sectional archwires were utilized for anterior retraction, with strategic archwire discontinuation between teeth 33–35 and 43–45. This design effectively minimized friction during space closure while facilitating controlled anteroposterior movement of the anterior segments. Class III elastics were initially applied from upper first molars to lower second premolars (U6-L5) and subsequently shifted to canines (U6-L3) after achieving anterior edge-to-edge relationship to reinforce lower anterior retraction force. Extrusion of upper molars was achieved to create adequate clearance for anterior crossbite correction. (Fig. 2 ) 3. Wire plus aligner (WA) orthodontics After resolution of the major crossbite components and completion of extraction space closure, clear aligners were used as an adjunctive finishing phase. The WA approach improved fine alignment, preserved arch form, and facilitated controlled expression of remaining tooth movements that would have been less predictable using fixed appliances alone. (Fig. 3 ) Serial measurements were collected throughout the 31-month active treatment period. Remarkably, despite bilateral premolar extractions and extensive space closure, the maxillary intermolar width remained unchanged at 49.5 mm, demonstrating complete transverse preservation. This finding sharply contrasted with classical expectations of transverse narrowing in extraction-based Class III camouflage treatment. At the end of therapy, both anterior and posterior crossbite were fully corrected, and ideal overjet and overbite were established. Facial esthetics improved with better upper lip support and normalization of the soft-tissue profile. The patient reported enhanced function and high satisfaction with treatment outcomes. Discussion Previous comparative studies have shown that premolar extractions may influence maxillary arch width and overall arch form, with extraction protocols generally associated with narrower transverse dimensions compared with non-extraction treatment [ 5 , 10 , 11 ]. While these long-term studies primarily addressed anteroposterior alignment and retention strategies, their findings underscore that dental arch stability is multifactorial, suggesting that transverse changes—when present—may also influence long-term outcomes [ 3 , 12 – 15 ]. Against this backdrop, the present case is notable because maxillary intermolar width remained completely preserved throughout treatment despite four-premolar extraction and crowding relief, constituting an uncommon biomechanical outcome. Several factors may explain this atypical transverse behavior. First, the inside-out technique used during early alignment is designed to transition palatally displaced incisors outward without compressing the lateral segments. By correcting the anterior crossbite before comprehensive space closure, this method minimizes the inward forces that often propagate transverse narrowing during initial leveling. Second, the use of sectional archwire mechanics with adjunctive Class III elastics allowed controlled expression of force systems during extraction space closure. Sectional mechanics, as described by Burstone, allow clinicians to isolate and control moment-to-force ratios during space closure, minimizing unwanted side effects commonly associated with continuous archwire mechanics [ 6 ]. This approach may have protected intermolar width by preventing the mesial migration of posterior segments into a constricted path. In addition, improved super-elastic nickel–titanium wires (ISW) provide light and continuous forces that enhance alignment efficiency and offer more controlled tooth movement compared with traditional stainless-steel wires [ 8 , 9 ]. The intrinsic form of the patient’s maxillary arch may also represent an important biological factor. Some arch forms exhibit inherent transverse resilience, influenced by palatal morphology, muscular balance, and alveolar bone thickness, enabling them to better resist constriction forces during space closure. This may partially explain why the expected transverse collapse did not occur in this case. The wire plus aligner (WA) approach facilitated final detailing by allowing rotational correction and improved marginal alignment during the finishing stage. Although clear aligners exhibit well-recognized limitations in producing certain buccolingual or torque movements, previous studies have demonstrated that their biomechanical expression is influenced by attachment design and material properties, which can enhance the predictability of specific tooth movements during finishing [ 16 – 18 ]. In this case, aligners were implemented after major sagittal and transverse corrections, providing high-precision control in the finishing phase while minimizing the risk of unwanted constriction. Previous studies have shown that the biomechanical expression of clear aligners—particularly the force systems generated by material stiffness and attachment design—can influence the predictability of specific tooth movements, supporting their use for precise detailing in the finishing stage [ 19 , 20 ]. The convergence of these biomechanical strategies—initial ISW leveling, inside-out technique, sectional archwire mechanics with Class III IME strategy, and a WA orthodontics—may collectively explain the complete correction of this complicated case. From a clinical perspective, this case highlights that extraction therapy in Class III camouflage treatment does not invariably lead to transverse narrowing. Instead, transverse outcomes may be modifiable through careful design and individualized sequencing of tooth movement. The findings also raise broader considerations about predicting transverse behavior in Class III patients. Conventional assumptions regarding extraction-induced constriction may not apply universally; anatomical variability, muscular influence, and appliance selection can modify expected biomechanical patterns. As this case demonstrates, patients with severe crowding and crossbite can still maintain stable transverse dimensions when force systems are carefully controlled. Continued exploration of such atypical responses may help refine current treatment paradigms and improve the predictability of outcomes for borderline non-surgical Class III cases. Conclusion This case highlights an uncommon presentation of skeletal Class III malocclusion characterized by the simultaneous presence of anterior and posterior crossbite and an unexpectedly stable maxillary transverse dimension despite four-premolar extraction therapy. Through the combined application of the inside-out technique, sectional archwire mechanics with adjunctive Class III elastics, and the wire-plus-aligner (WA) orthodontic approach, complete correction of the crossbite was achieved without inducing the transverse constriction commonly associated with extraction-based camouflage treatment. The preservation of intermolar width throughout treatment suggests that arch-form stability may be influenced by a combination of patient-specific anatomic factors and carefully controlled biomechanical strategies. This finding challenges traditional expectations of maxillary narrowing during extraction space closure and underscores the importance of individualized biomechanical planning in complex Class III cases. Recognizing such atypical transverse responses may contribute to more accurate prediction of treatment outcomes and support the refinement of non-surgical camouflage protocols in clinical practice. Abbreviations ANB: A point–Nasion–B point angle SNA: Sella–Nasion–A point angle SNB: Sella–Nasion–B point angle ISW: Improved super-elastic nickel–titanium alloy wire WA: Wire plus aligner orthodontics Declarations Acknowledgements The authors thank the clinical, imaging, and administrative staff of the Department of Dentistry, China Medical University Hospital, for their assistance during treatment and documentation. The authors also appreciate the support provided by the School of Dentistry, China Medical University. Author contributions Yu-Hsiang Chang drafted the manuscript, performed clinical treatment, and organized data acquisition. Yi-Mien Cheng contributed to diagnosis, literature review, and manuscript revision. Yuan-Hou Chen provided clinical supervision and treatment planning guidance. Jian-Hong Yu oversaw the project, provided senior orthodontic consultation, and approved the final version of the manuscript. All authors read and approved the final manuscript. Funding No external funding was received for this study . Data availability All data generated or analyzed during this case report are included in this published article. Ethics approval and consent to participate The authors declare they have the ethics approval and consent to participate in this case report. Consent for publication Written informed consent for publication of all clinical information, photographs, and radiographic images was obtained from the patient. A copy of the written consent is available for review by the Editor upon request. Competing interests The authors declare that they have no competing interests. References Guyer EC, Ellis EE 3rd, McNamara JA Jr, Behrents RG. Components of class III malocclusion in juveniles and adolescents. Angle Orthod. 1986;56(1):7–30. Ngan P, Moon W. Evolution of Class III treatment in orthodontics. Am J Orthod Dentofac Orthop. 2015;148:22–36. Little RM, Riedel RA, Artun J. An evaluation of changes in mandibular anterior alignment from 10 to 20 years postretention. Am J Orthod Dentofac Orthop. 1988;93:423–8. Shields TE, Little RM, Chapko MK. Stability and relapse of mandibular anterior alignment: a cephalometric appraisal of first premolar extraction cases treated by traditional edgewise orthodontics. Am J Orthod. 1985;87:27–38. Kim E, Gianelly AA. Extraction vs nonextraction: arch widths and smile esthetics. Angle Orthod. 2003;73:354–8. Burstone CJ. The segmented arch approach to space closure. Am J Orthod. 1982;82:361–78. Drescher D, Bourauel C, Schumacher HA. Frictional forces between bracket and arch wire. Am J Orthod Dentofac Orthop. 1989;96:397–404. Cheng YM, Lin CC, Lo YC, Chen YH, Yu JH. Improved super-elastic Ti-Ni alloy wire for the treatment of skeletal Class III with unilateral buccally positioned high canine. Taiwan J Orthod. 2023;35:Article 5. Chang YHS, Chen YH, Yu JH. Improved superelastic Ni-Ti alloy wire for treating skeletal Class III malocclusion combined with anterior crossbite: a case report. World J Clin Cases. 2025;13:101545. Paquette DE, Beattie JR, Johnston LE Jr.. A long-term comparison of nonextraction and premolar extraction edgewise therapy in borderline Class II patients. Am J Orthod Dentofac Orthop. 1992;102:1–14. Staggers JA. A comparison of results of second molar and first premolar extraction treatment. Am J Orthod Dentofac Orthop. 1990;98:430–6. Artun J, Garol JD, Little RM. Long-term stability of mandibular incisors following successful treatment of Class II, Division 1 malocclusions. Angle Orthod. 1996;66:229–38. Zachrisson BU. Important aspects of long-term stability. J Clin Orthod. 1997;31:562–83. Sadowsky C, Schneider BJ, BeGole EA, Tahir E. Long-term stability after orthodontic treatment: nonextraction with prolonged retention. Am J Orthod Dentofac Orthop. 1994;106:243–9. Johnston CD, Littlewood SJ. Retention in orthodontics. Br Dent J. 2015;218:119–22. Chen PY, Huang HL, Yu JH, Hsu JT. Effects of attachment design and aligner material on mandibular canine distal bodily movement in aligner treatment. J Med Biol Eng. 2024;44:777–87. Kravitz ND, Kusnoto B, BeGole E, Obrez A, Agran B. How well does Invisalign work? A prospective clinical study evaluating the efficacy of tooth movement with Invisalign. Am J Orthod Dentofac Orthop. 2009;135:27–35. Simon M, Keilig L, Schwarze J, Jung BA, Bourauel C. Forces and moments generated by removable thermoplastic aligners: incisor torque, premolar derotation, and molar distalization. Am J Orthod Dentofac Orthop. 2014;145:728–36. Rossini G, Parrini S, Castroflorio T, Deregibus A, Debernardi CL. Efficacy of clear aligners in controlling orthodontic tooth movement: a systematic review. Angle Orthod. 2015;85:881–9. Gomez JP, Peña FM, Martínez V, Giraldo DC, Cardona CI. Initial force systems during bodily tooth movement with plastic aligners and composite attachments: a three-dimensional finite element analysis. Angle Orthod. 2015;85:665–72. 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. 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1","display":"","copyAsset":false,"role":"figure","size":322919,"visible":true,"origin":"","legend":"\u003cp\u003eTransverse dimensional outcomes following the inside-out technique. (A) Pretreatment presentation showing anterior and posterior crossbite with maxillary intermolar width of 49.5 mm and mandibular intermolar width of 49.0 mm (August 1, 2022). (B) Application of the inside-out technique demonstrating controlled transverse development (January 24, 2024). (C) Posttreatment outcome showing harmonious arch coordination with maintenance of maxillary intermolar width at 49.5 mm and coordinated reduction in mandibular intermolar width to 47.0 mm following premolar extraction therapy (April 23, 2025). The inside-out technique effectively preserved maxillary transverse dimension while achieving optimal occlusal coordination.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8243460/v1/4292f35a3957e4f2e9028156.png"},{"id":98431561,"identity":"04f3ed40-c31a-4308-b8f1-1d9deb7cad54","added_by":"auto","created_at":"2025-12-17 16:47:55","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":652447,"visible":true,"origin":"","legend":"\u003cp\u003eTo reduce friction during anterior retraction, the archwire was cut between 33–35 and 43–45, converting the lower anterior segment into an independent unit. This design minimized sliding resistance and enabled posterior extrusion. Class III elastics were initially applied from U6–L5 for anchorage and vertical control, then shifted to U6–L3 to achieve sagittal correction and anterior crossbite resolution.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-8243460/v1/0c57e939a8f32f3d1d2dd09d.png"},{"id":98181342,"identity":"47fc34bb-6e74-4222-b191-2b0c0e0c00f0","added_by":"auto","created_at":"2025-12-15 01:10:26","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":241121,"visible":true,"origin":"","legend":"\u003cp\u003eFinishing phase using wire plus aligner (WA) orthodontics. The fixed appliance phase ended early per patient preference, and clear aligners were applied for final detailing. Rotation of tooth #11 (8.0°) was corrected within 2 months, achieving precise alignment and optimal arch coordination.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-8243460/v1/7d3698c8aeb3480435581bc3.png"},{"id":106404598,"identity":"b72af05a-e8c8-43c6-9afd-6f0a4c77a4e0","added_by":"auto","created_at":"2026-04-08 09:16:20","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2109703,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8243460/v1/84f2dad7-7d28-4bd2-aabe-a321bcd6ea4d.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Preserved maxillary transverse width following bilateral premolar extraction in a skeletal Class III malocclusion: a case report","fulltext":[{"header":"Background","content":"\u003cp\u003eSkeletal Class III malocclusion displays diverse skeletal components\u0026mdash;including maxillary retrusion, mandibular prognathism, and transverse or vertical imbalances\u0026mdash;reflecting its broad phenotypic spectrum [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Its clinical presentation often includes anterior crossbite, reduced facial convexity, and functional shifts, and its prevalence is notably higher in East Asian populations. The coexistence of both anterior and posterior crossbite represents a particularly challenging subtype, as it reflects simultaneous sagittal and transverse discrepancies. Early identification of skeletal Class III discrepancies is critical because dental compensation can obscure the true severity of the underlying skeletal imbalance, potentially influencing treatment decisions [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn adult patients who decline orthognathic surgery, camouflage treatment remains an important therapeutic alternative. However, extraction therapy\u0026mdash;especially the removal of first premolars\u0026mdash;is associated with predictable transverse effects. Little et al. and Shields et al. demonstrated that premolar extraction cases often exhibit long-term changes in mandibular anterior alignment, suggesting a susceptibility to post-retention instability [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. In addition, Kim and Gianelly reported notable differences in arch widths and smile esthetics between extraction and non-extraction treatment modalities, indicating that tooth removal may alter transverse dental relationships and overall arch form [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. These findings have shaped the conventional expectation that extraction mechanics inherently reduce transverse dimension in non-surgical Class III patients.\u003c/p\u003e\u003cp\u003eDespite this, biomechanical research suggests that arch width changes are not solely determined by extraction patterns. The segmented arch technique offers a well-controlled force system, which can help clinicians minimize unintended effects during space closure, including potential changes in arch form [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Furthermore, differences in bracket\u0026ndash;archwire friction can modify the efficiency and predictability of sliding mechanics during space closure, which may in turn influence the overall pattern in which tooth movement is expressed [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. The clinical use of improved super-elastic nickel-titanium wires has been documented in case reports detailing successful orthodontic management of complex skeletal Class III malocclusions [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], supporting their role in comprehensive treatment approaches that may include controlled alignment and dental compensation.\u003c/p\u003e\u003cp\u003eGiven the scarcity of reports describing atypical transverse behavior during non-surgical Class III treatment, particularly cases showing preserved or stable arch width despite premolar extractions, further documentation is warranted. This case contributes to the understanding of biomechanical and biological variability in transverse response, highlighting the need for individualized diagnosis and careful interpretation of traditional expectations in camouflage therapy.\u003c/p\u003e"},{"header":"Case Presentation","content":"\u003cp\u003eA 19-year-old woman presented with concerns of unesthetic dental alignment and functional difficulty when incising food. She was medically healthy, with no craniofacial trauma, systemic conditions, or parafunctional habits. Extraoral examination revealed a concave soft-tissue profile, reduced maxillary prominence, and a mild mandibular deviation to the right. No temporomandibular disorders were noted.\u003c/p\u003e\u003cp\u003eIntraoral examination showed an uncommon combination of both anterior and bilateral posterior crossbite. The patient presented with an anterior crossbite (overjet \u0026minus;\u0026thinsp;1.5 mm) and bilateral posterior crossbite. Maxillary crowding was severe, measuring \u0026minus;\u0026thinsp;4.0 mm on the right and \u0026minus;\u0026thinsp;9.0 mm on the left; mandibular crowding measured \u0026minus;\u0026thinsp;5.5 mm and \u0026minus;\u0026thinsp;4.5 mm, respectively. A supernumerary tooth was present in the anterior maxilla. Periodontal tissues were healthy.\u003c/p\u003e\u003cp\u003ePanoramic radiography showed normal alveolar bone levels and intact root morphology. Lateral cephalometric analysis confirmed skeletal Class III malocclusion (SNA 80.0\u0026deg;, SNB 84.5\u0026deg;, ANB \u0026minus;\u0026thinsp;4.5\u0026deg;) with a mandibular plane angle of 28.0\u0026deg;. Mandibular incisors were retroclined due to dental compensation. Baseline maxillary intermolar width was 49.5 mm\u0026mdash;within the upper range of normal\u0026mdash;despite the presence of crowding and crossbite.\u003c/p\u003e\u003cp\u003eGiven the patient\u0026rsquo;s refusal of orthognathic surgery, a non-surgical camouflage plan was adopted. Because of the crowding severity and the need for both sagittal and transverse correction, extraction of all four first premolars was indicated. The treatment incorporated three key clinical strategies to manage the unusual combination of crossbite patterns:\u003c/p\u003e\u003cp\u003e\u003cb\u003e1. Inside-out technique\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe inside-out technique was implemented using customized archwires with reversed insertion (inner surface facing outward). This approach provided controlled bilateral expansion force, successfully maintaining maxillary transverse dimension at 49.5 mm throughout the treatment despite extraction therapy. (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e)\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003e2. Sectional archwire mechanics with adjunctive Class III elastics\u003c/b\u003e\u003c/p\u003e\u003cp\u003eSectional archwires were utilized for anterior retraction, with strategic archwire discontinuation between teeth 33\u0026ndash;35 and 43\u0026ndash;45. This design effectively minimized friction during space closure while facilitating controlled anteroposterior movement of the anterior segments. Class III elastics were initially applied from upper first molars to lower second premolars (U6-L5) and subsequently shifted to canines (U6-L3) after achieving anterior edge-to-edge relationship to reinforce lower anterior retraction force. Extrusion of upper molars was achieved to create adequate clearance for anterior crossbite correction. (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e)\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003e3. Wire plus aligner (WA) orthodontics\u003c/b\u003e\u003c/p\u003e\u003cp\u003eAfter resolution of the major crossbite components and completion of extraction space closure, clear aligners were used as an adjunctive finishing phase. The WA approach improved fine alignment, preserved arch form, and facilitated controlled expression of remaining tooth movements that would have been less predictable using fixed appliances alone. (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e)\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eSerial measurements were collected throughout the 31-month active treatment period. Remarkably, despite bilateral premolar extractions and extensive space closure, the maxillary intermolar width remained unchanged at 49.5 mm, demonstrating complete transverse preservation. This finding sharply contrasted with classical expectations of transverse narrowing in extraction-based Class III camouflage treatment.\u003c/p\u003e\u003cp\u003eAt the end of therapy, both anterior and posterior crossbite were fully corrected, and ideal overjet and overbite were established. Facial esthetics improved with better upper lip support and normalization of the soft-tissue profile. The patient reported enhanced function and high satisfaction with treatment outcomes.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003ePrevious comparative studies have shown that premolar extractions may influence maxillary arch width and overall arch form, with extraction protocols generally associated with narrower transverse dimensions compared with non-extraction treatment [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. While these long-term studies primarily addressed anteroposterior alignment and retention strategies, their findings underscore that dental arch stability is multifactorial, suggesting that transverse changes\u0026mdash;when present\u0026mdash;may also influence long-term outcomes [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan additionalcitationids=\"CR13 CR14\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Against this backdrop, the present case is notable because maxillary intermolar width remained completely preserved throughout treatment despite four-premolar extraction and crowding relief, constituting an uncommon biomechanical outcome.\u003c/p\u003e\u003cp\u003eSeveral factors may explain this atypical transverse behavior. First, the inside-out technique used during early alignment is designed to transition palatally displaced incisors outward without compressing the lateral segments. By correcting the anterior crossbite before comprehensive space closure, this method minimizes the inward forces that often propagate transverse narrowing during initial leveling. Second, the use of sectional archwire mechanics with adjunctive Class III elastics allowed controlled expression of force systems during extraction space closure. Sectional mechanics, as described by Burstone, allow clinicians to isolate and control moment-to-force ratios during space closure, minimizing unwanted side effects commonly associated with continuous archwire mechanics [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. This approach may have protected intermolar width by preventing the mesial migration of posterior segments into a constricted path.\u003c/p\u003e\u003cp\u003eIn addition, improved super-elastic nickel\u0026ndash;titanium wires (ISW) provide light and continuous forces that enhance alignment efficiency and offer more controlled tooth movement compared with traditional stainless-steel wires [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. The intrinsic form of the patient\u0026rsquo;s maxillary arch may also represent an important biological factor. Some arch forms exhibit inherent transverse resilience, influenced by palatal morphology, muscular balance, and alveolar bone thickness, enabling them to better resist constriction forces during space closure. This may partially explain why the expected transverse collapse did not occur in this case.\u003c/p\u003e\u003cp\u003eThe wire plus aligner (WA) approach facilitated final detailing by allowing rotational correction and improved marginal alignment during the finishing stage. Although clear aligners exhibit well-recognized limitations in producing certain buccolingual or torque movements, previous studies have demonstrated that their biomechanical expression is influenced by attachment design and material properties, which can enhance the predictability of specific tooth movements during finishing [\u003cspan additionalcitationids=\"CR17\" citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. In this case, aligners were implemented after major sagittal and transverse corrections, providing high-precision control in the finishing phase while minimizing the risk of unwanted constriction. Previous studies have shown that the biomechanical expression of clear aligners\u0026mdash;particularly the force systems generated by material stiffness and attachment design\u0026mdash;can influence the predictability of specific tooth movements, supporting their use for precise detailing in the finishing stage [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe convergence of these biomechanical strategies\u0026mdash;initial ISW leveling, inside-out technique, sectional archwire mechanics with Class III IME strategy, and a WA orthodontics\u0026mdash;may collectively explain the complete correction of this complicated case. From a clinical perspective, this case highlights that extraction therapy in Class III camouflage treatment does not invariably lead to transverse narrowing. Instead, transverse outcomes may be modifiable through careful design and individualized sequencing of tooth movement.\u003c/p\u003e\u003cp\u003eThe findings also raise broader considerations about predicting transverse behavior in Class III patients. Conventional assumptions regarding extraction-induced constriction may not apply universally; anatomical variability, muscular influence, and appliance selection can modify expected biomechanical patterns. As this case demonstrates, patients with severe crowding and crossbite can still maintain stable transverse dimensions when force systems are carefully controlled. Continued exploration of such atypical responses may help refine current treatment paradigms and improve the predictability of outcomes for borderline non-surgical Class III cases.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis case highlights an uncommon presentation of skeletal Class III malocclusion characterized by the simultaneous presence of anterior and posterior crossbite and an unexpectedly stable maxillary transverse dimension despite four-premolar extraction therapy. Through the combined application of the inside-out technique, sectional archwire mechanics with adjunctive Class III elastics, and the wire-plus-aligner (WA) orthodontic approach, complete correction of the crossbite was achieved without inducing the transverse constriction commonly associated with extraction-based camouflage treatment.\u003c/p\u003e\u003cp\u003eThe preservation of intermolar width throughout treatment suggests that arch-form stability may be influenced by a combination of patient-specific anatomic factors and carefully controlled biomechanical strategies. This finding challenges traditional expectations of maxillary narrowing during extraction space closure and underscores the importance of individualized biomechanical planning in complex Class III cases. Recognizing such atypical transverse responses may contribute to more accurate prediction of treatment outcomes and support the refinement of non-surgical camouflage protocols in clinical practice.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eANB: A point\u0026ndash;Nasion\u0026ndash;B point angle\u003c/p\u003e\n\u003cp\u003eSNA: Sella\u0026ndash;Nasion\u0026ndash;A point angle\u003c/p\u003e\n\u003cp\u003eSNB: Sella\u0026ndash;Nasion\u0026ndash;B point angle\u003c/p\u003e\n\u003cp\u003eISW: Improved super-elastic nickel\u0026ndash;titanium alloy wire\u003c/p\u003e\n\u003cp\u003eWA: Wire plus aligner orthodontics\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors thank the clinical, imaging, and administrative staff of the Department of Dentistry, China Medical University Hospital, for their assistance during treatment and documentation. The authors also appreciate the support provided by the School of Dentistry, China Medical University.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eYu-Hsiang Chang\u003c/strong\u003e drafted the manuscript, performed clinical treatment, and organized data acquisition.\u003cbr\u003e\u003cstrong\u003eYi-Mien Cheng\u003c/strong\u003e contributed to diagnosis, literature review, and manuscript revision.\u003cbr\u003e\u003cstrong\u003eYuan-Hou Chen\u003c/strong\u003e provided clinical supervision and treatment planning guidance.\u003cbr\u003e\u003cstrong\u003eJian-Hong Yu\u003c/strong\u003e oversaw the project, provided senior orthodontic consultation, and approved the final version of the manuscript.\u003cbr\u003e\u0026nbsp;All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo external funding was received for this study\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data generated or analyzed during this case report are included in this published article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare they have the ethics approval and consent to participate in this case report.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWritten informed consent for publication of all clinical information, photographs, and radiographic images was obtained from the patient. A copy of the written consent is available for review by the Editor upon request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eGuyer EC, Ellis EE 3rd, McNamara JA Jr, Behrents RG. Components of class III malocclusion in juveniles and adolescents. Angle Orthod. 1986;56(1):7\u0026ndash;30.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNgan P, Moon W. Evolution of Class III treatment in orthodontics. Am J Orthod Dentofac Orthop. 2015;148:22\u0026ndash;36.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLittle RM, Riedel RA, Artun J. An evaluation of changes in mandibular anterior alignment from 10 to 20 years postretention. Am J Orthod Dentofac Orthop. 1988;93:423\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eShields TE, Little RM, Chapko MK. Stability and relapse of mandibular anterior alignment: a cephalometric appraisal of first premolar extraction cases treated by traditional edgewise orthodontics. Am J Orthod. 1985;87:27\u0026ndash;38.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKim E, Gianelly AA. Extraction vs nonextraction: arch widths and smile esthetics. Angle Orthod. 2003;73:354\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBurstone CJ. The segmented arch approach to space closure. Am J Orthod. 1982;82:361\u0026ndash;78.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDrescher D, Bourauel C, Schumacher HA. Frictional forces between bracket and arch wire. Am J Orthod Dentofac Orthop. 1989;96:397\u0026ndash;404.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCheng YM, Lin CC, Lo YC, Chen YH, Yu JH. Improved super-elastic Ti-Ni alloy wire for the treatment of skeletal Class III with unilateral buccally positioned high canine. Taiwan J Orthod. 2023;35:Article 5.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChang YHS, Chen YH, Yu JH. Improved superelastic Ni-Ti alloy wire for treating skeletal Class III malocclusion combined with anterior crossbite: a case report. World J Clin Cases. 2025;13:101545.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePaquette DE, Beattie JR, Johnston LE Jr.. A long-term comparison of nonextraction and premolar extraction edgewise therapy in borderline Class II patients. Am J Orthod Dentofac Orthop. 1992;102:1\u0026ndash;14.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eStaggers JA. A comparison of results of second molar and first premolar extraction treatment. Am J Orthod Dentofac Orthop. 1990;98:430\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eArtun J, Garol JD, Little RM. Long-term stability of mandibular incisors following successful treatment of Class II, Division 1 malocclusions. Angle Orthod. 1996;66:229\u0026ndash;38.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZachrisson BU. Important aspects of long-term stability. J Clin Orthod. 1997;31:562\u0026ndash;83.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSadowsky C, Schneider BJ, BeGole EA, Tahir E. Long-term stability after orthodontic treatment: nonextraction with prolonged retention. Am J Orthod Dentofac Orthop. 1994;106:243\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJohnston CD, Littlewood SJ. Retention in orthodontics. Br Dent J. 2015;218:119\u0026ndash;22.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChen PY, Huang HL, Yu JH, Hsu JT. Effects of attachment design and aligner material on mandibular canine distal bodily movement in aligner treatment. J Med Biol Eng. 2024;44:777\u0026ndash;87.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKravitz ND, Kusnoto B, BeGole E, Obrez A, Agran B. How well does Invisalign work? A prospective clinical study evaluating the efficacy of tooth movement with Invisalign. Am J Orthod Dentofac Orthop. 2009;135:27\u0026ndash;35.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSimon M, Keilig L, Schwarze J, Jung BA, Bourauel C. Forces and moments generated by removable thermoplastic aligners: incisor torque, premolar derotation, and molar distalization. Am J Orthod Dentofac Orthop. 2014;145:728\u0026ndash;36.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRossini G, Parrini S, Castroflorio T, Deregibus A, Debernardi CL. Efficacy of clear aligners in controlling orthodontic tooth movement: a systematic review. Angle Orthod. 2015;85:881\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGomez JP, Pe\u0026ntilde;a FM, Mart\u0026iacute;nez V, Giraldo DC, Cardona CI. Initial force systems during bodily tooth movement with plastic aligners and composite attachments: a three-dimensional finite element analysis. Angle Orthod. 2015;85:665\u0026ndash;72.\u003c/span\u003e\u003c/li\u003e\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":"Anterior crossbite, Posterior crossbite, Skeletal Class III, Transverse width, Premolar extraction, Maxillary stability, Orthodontic case report","lastPublishedDoi":"10.21203/rs.3.rs-8243460/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8243460/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eSkeletal Class III malocclusion with simultaneous anterior and posterior crossbite is uncommon and often presents with combined sagittal and transverse discrepancies. Extraction-based camouflage treatment is traditionally associated with predictable reductions in maxillary transverse dimensions during space closure. However, rare cases may deviate from this pattern. This report describes a unique presentation in which maxillary intermolar width remained fully preserved following bilateral premolar extractions, highlighting an unusual transverse response with clinical relevance for treatment planning.\u003c/p\u003e\u003ch2\u003eCase presentation:\u003c/h2\u003e\u003cp\u003e19-year-old woman presented with a concave facial profile, anterior and posterior crossbite, and dental crowding. She declined orthognathic surgery, and a non-surgical camouflage plan was adopted. Four premolars were extracted to create space for alignment and crossbite correction. The treatment sequence incorporated an inside-out technique aimed at maintaining transverse stability while assisting correction of the posterior crossbite, sectional archwire mechanics with adjunctive Class III elastics during space closure, and a wire-plus-aligner approach in the finishing phase for high-precision detailing. Throughout the 31-month treatment period, maxillary intermolar width remained unchanged, contrary to the transverse constriction commonly associated with extraction mechanics. Both anterior and posterior crossbite were corrected, and facial esthetics improved.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e\u003cp\u003eThis case demonstrates an unusual transverse response during extraction-based camouflage treatment of skeletal Class III malocclusion, with complete preservation of maxillary intermolar width. Recognition of such variability may help clinicians better anticipate potential transverse outcomes when planning complex Class III camouflage treatment.\u003c/p\u003e","manuscriptTitle":"Preserved maxillary transverse width following bilateral premolar extraction in a skeletal Class III malocclusion: a case report","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-15 01:10:20","doi":"10.21203/rs.3.rs-8243460/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":"8e3497da-8f9e-439b-8ba3-beeb9b28fea8","owner":[],"postedDate":"December 15th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-04-08T06:56:29+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-15 01:10:20","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8243460","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8243460","identity":"rs-8243460","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}