Evaluate the Changes in Root Length of the Lower Anterior Teeth after Intrusion with Clear Aligners

Evaluate the Changes in Root Length of the Lower Anterior Teeth after Intrusion with Clear Aligners | 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 Article Evaluate the Changes in Root Length of the Lower Anterior Teeth after Intrusion with Clear Aligners xuejin yuan, mingmin zhu, mi zhao, yanxiao zhang This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6835983/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract Objective: To evaluate the effects on root length and root resorption of the lower anterior teeth after intrusion with clear aligners in adults with deep overbite, using three-dimensional imaging via cone-beam computed tomography (CBCT). Methods: From January 2019 to December 2023, twenty adult patients treated at the orthodontics department with clear aligners designed specifically for the intrusion of the lower anterior teeth were selected for this study. CBCT scans were taken before and after treatment to measure changes in the root length of the lower anterior teeth, and the data were analyzed statistically. Results: The change in root length of the mandibular central incisors, lateral incisors, and canines was statistically significant (P<0.01) in all cases. Conclusion: 1.After the use of clear aligners for the intrusion of the lower anterior teeth, a reduction in root length of the lower anterior teeth was observed (P<0.01). 2.The root absorption of the mandibular canines is more than that of the lower central incisor and lateral incisor. Biological sciences/Biophysics Health sciences/Medical research Aligners CBCT root length lower anterior Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Clear aligners (CAs) have gained increasing popularity in orthodontic treatment due to their aesthetic appeal and comfort advantages. Initially limited to mild-to-moderate malocclusions, recent advancements in invisible orthodontic technologies and material properties have expanded their use to more complex cases, enabling improved outcomes [1] . Key techniques contributing to this progress include optimized treatment design, attachment composition, and vertical control for intrusion [2] . Although there are more reports on the intrusion efficiency of clear aligners, studies examining changes in the root length of lower anterior/posterior teeth remain scarce. Conventional clinical techniques for lowering anterior teeth, such as bite plates, reverse-curve archwires, and utility arches, often cause labial inclination [3] . The segmented arch technique introduced by Burstone in 1970 helps intrude mandibular incisors and level the SPEE curve [4] . Compared to fixed braces, brace-free clear aligners cover the entire tooth surface, allowing the intrusive force to be applied closer to the teeth’s center of resistance. This enables all incisors to move more deeply along their longitudinal axis. Studies indicate that the clear aligner techniques tend to result in a near-bodily movement, achieving up to 47% intrusion efficiency for mandibular incisors [5] . Research by Song et al. (2018) found that the intrusion efficiency for mandibular lateral incisors is highest at 54.6%, followed by mandibular central incisors and mandibular canines at 48.1% and 42.4%, respectively [6] . Patients undergoing treatment with the brace-free clear aligner technique effectively reduced deep overbite due to their lowered mandibular anterior teeth [7] . However, tooth intrusion also tends to increase root resorption, which can be classified into three degrees: (1) Mild‌: the root shortening is less than 2 mm or the change of the root-crown length ratio is less than 10%. (2) ‌Moderate‌: the root shortening is equal to or more than 2 mm but less than 1/3 of the original length, or the change of the root-crown length ratio is between 10% and 20%. (3) ‌Severe‌: the root shortening is more than 1/3 of the original length, or the change of the root-crown length ratio is more than 20% ［ 8 ， 9 ］ . Root resorption is influenced by several factors, including patient age, treatment duration, malocclusion type, and force application. Studies indicate that intermittent force application tends to reduce or even prevent root resorption [10] . Due to their feature of being removable, clear aligners deliver intermittent forces, which may contribute to reduced root resorption and better periodontal health compared to continuous forces. Although histological studies report that root resorption incidence with orthodontic treatment exceeds 90% [11] , radiographic measurements tend to show slightly lower rates. This study evaluates changes in root length of mandibular anterior teeth before and after clear aligner intrusion using the CBCT technique and investigates possible factors influencing root resorption. ‌1. Basic Information and Methods ‌1.1 Patients: A total of 20 adult patients (7 males and 13 females) underwent orthodontic treatment at the Orthodontic Department of Wuxi Stomatological Hospital between January 2019 and December 2023. All the patients were aged 18 to 41 years old, with a mean age of 26.60 ± 6.66 years. They were all treated using full-mouth orthodontic correction with brace-free, clear aligner-based invisible appliances. The frog-jump technique was used to intrude the mandibular anterior teeth. CBCT scans were obtained before and after treatment. Eligibility requirements:‌ 1. Having all the mandibular anterior teeth. 2. No extractions performed during orthodontic treatment. 3. Healthy periodontal tissues with no significant root or alveolar bone resorption. 4. Aged above 18 years. 5. Exclusive use of clear aligners throughout the treatment period. ‌Exclusions:‌ 1. Presence of radiographically diagnosed pulpal or periapical lesions in mandibular anterior teeth, or a history of root canal treatment. 2. Clinical signs of periodontitis affecting anterior teeth (e.g., clinical attachment loss) or alveolar bone resorption (CEJ-BC distance >2 mm) on radiographic evaluation. 3. Abnormalities in the number, morphology, or eruption of mandibular anterior teeth. 4. Having undergone orthodontic treatment. 5. Suffering from systemic diseases that affect bone metabolism or dental health. ‌1.2 Research Methods‌ All patients underwent lateral cephalogram and CBCT imaging (KaVo Dental Gmbh, Germany) at the Radiology Department of Wuxi Stomatological Hospital. The scanning parameters were shown as follows: Voltage: 120 kV; current: 5.0 mA; slice thickness: 0.3 mm; and exposure time: 20 s. During imaging, patients were positioned with their mandibles stabilized on the chin rest, their facial midline perpendicular to the ground and aligned with the scanner’s central axis, and their occlusal plane parallel to the ground. All scans were taken by the same radiologist, strictly adhering to standardized protocols and using the built-in NNT Viewer software. CBCT measurements were conducted as follows: Images were reconstructed in the MPR window using the editing function. The horizontal cross-section of the target tooth was selected and aligned with its cervical part. The sagittal plane was then chosen to bisect the mesiodistal dimension of the tooth and adjusted to pass through its long axis. Using the software’s measurement function, the required distances were measured according to the prompts. Next, the target tooth in the mandibular anterior tooth region was positioned on the horizontal plane, adjusting the section so that the sagittal section traversed the maximum buccolingual surface (Figure 1). The coronal longitudinal section was set at an angle to traverse the cusp and root tip (Figure 2). The sagittal longitudinal section was finely adjusted to also pass through the cusp and root tip (Figure 3). Repeated positioning and adjustments were performed to confirm the optimal sagittal buccolingual cross-section. All measurements were taken using the built-in NNT Viewer software. To minimize errors, each parameter was measured three times, and their mean value was used for analysis. ‌1.3 Measurement Parameters‌ (1) Root length: Distance between Point 2 and Point 5 (Figure 4). (2) L-MP (mm): Vertical distance from the incisal edge of the mandibular anterior tooth to the mandibular plane. The difference between pre-and post-treatment values represents the actual intrusion magnitude(‌Figure 5). (3) L-MP (°): Angle between the long axis of the mandibular anterior tooth and the mandibular plane. The difference between pre-and post-treatment values reflects changes in labial inclination(‌Figure 5). (4) Designed intrusion magnitude: Crown intrusion (I) values obtained from the ClinCheck tooth movement table (mm). Declaration that the patient signed the informed consent form and was reviewed by the Ethics Committee of Wuxi Stomatological Hospital (Ethics number: 025061101). Declaration that all experiments were performed in accordance with relevant guidelines and regulations. ‌1.4 Statistical Analysis‌ Statistical analysis was conducted using SPSS 22.0 software. Paired t-tests were used to compare pre- and post-treatment measurements, with statistical significance set at p < 0.05. ‌Table 4: Changes in root length of mandibular anterior teeth (mm)‌ Pre-treatment Post-treatment Pre-Post Difference T-value P-value L1 11.29±0.98 10.27±0.81 1.02 9.074 0.000** L2 12.10±1.21 10.99±0.99 1.11 8.360 0.000** L3 14.23±1.47 13.02±1.45 1.21 8.164 0.000** ‌ P<0.05 * , p<0.01 ** ‌Table 5: Comparison of actual vs. designed intrusion magnitude in mandibular anterior teeth (mm) Actual Intrusion Designed Intrusion Difference (Designed - Actual) T-value P-value L1 1.78±0.66 3.34±1.42 1.56±0.99 6.310 0.004** L2 1.73±0.81 3.27±1.30 1.54±0.71 8.664 0.000** L3 0.95±0.42 2.44±0.75 1.49±0.56 10.587 0.000** ‌ P<0.05 * , p<0.01 ** ‌Table 6: Changes in L/MP angle of mandibular anterior teeth (°) Pre-treatment Post-treatment Difference T-value P-value L1 92.86±6.48 93.17±4.03 3.76±4.81 0.170 0.868 L2 92.46±6.19 94.10±3.14 3.48±4.52 0.960 0.352 L3 94.48±4.72 95.51±2.89 2.08±1.77 0.918 0.373 P<0.05*, p<0.01** 2. Results In this study, the average root length of mandibular central incisors before treatment was (11.29 ± 0.98) mm. After intrusion, it decreased to (10.27 ± 0.81) mm, showing a statistically significant difference (P < 0.01). Similarly, the average length of mandibular lateral incisors before treatment was (12.10 ± 1.21) mm. This length reduced to (10.99 ± 0.99) mm after intrusion, showing a statistically significant difference (P < 0.01). The mandibular canines had an average length of (14.23 ± 1.47) mm before treatment. This length reduced to (13.02 ± 1.45) mm post-intrusion, showing a statistically significant difference (P < 0.01)(‌Table 4). All mandibular anterior teeth demonstrated statistically significant intrusion differences (P < 0.01), accompanied by root shortening and absorption. While different degrees of intrusion were observed across all mandibular anterior teeth (P 0.05)(‌Table 6). 3. Discussion A deep overbite is a relatively common type of malocclusion. Its correction usually involves principles such as labial inclination of the anterior teeth, intrusion of the anterior teeth, extrusion of the posterior teeth, etc. When intruding the anterior teeth, the patient’s gingival display during smiling should be taken into account. Since adults lack growth potential and extrusion of posterior molars often tends to relapse, intrusion of the mandibular anterior teeth is a more commonly chosen option to improve deep overbite. Bite plates, reverse curve arches, intrusion auxiliary arches, and segmental arches are usually used for intruding mandibular anterior teeth. However, these methods require precise archwire bending, can reduce patient comfort, and demand excellent patient compliance. With the advancement of implant anchorage techniques, mini-implants can achieve effective intrusion. However, their placement is invasive, carries risks of loosening or failure, and often faces patient resistance. In clear aligner treatment of deep overbite cases, mandibular anterior intrusion mimics the mechanism of reverse curve arches used in fixed appliances [ 12 ] . As a force-efficient system, clear aligners can intrude teeth without auxiliary devices. Multiple international studies have demonstrated the high predictability of deep overbite correction with clear aligners, consistently reporting favorable outcomes in mandibular anterior intrusion [ 13 – 15 ] . Therefore, when treating deep overbite with clear aligners, clinicians should prioritize anterior intrusion to open the bite and fully leverage the system's advantages. Root resorption is one of the most common complications in orthodontics. It has a multifactorial etiology that involves biological variability, genetic predisposition, and mechanical factors. Its mechanism involves two phases: initial surface damage exposing mineralized tissue, followed by multinucleated cell colonization triggering resorption. Without sustained stimulation, cementum-like repair occurs within 2 to 3 weeks. However, persistent inflammation can cause deeper damage to the dentin and lead to radiographically detectable resorption. Finite element analyses simulating clear aligner intrusion of mandibular anterior teeth with varying labial inclinations show that the greater the deviation of the labial inclination from the normal value of the mandibular anterior teeth, the greater the stress of the tooth root on the labial and lingual sides. These stress concentration areas increase the risk of root resorption. Therefore, when performing intrusion of mandibular anterior teeth, it is important not only to consider the amount of intrusion but also to pay attention to changes on the labial and lingual sides of the teeth to prevent root resorption [ 16 , 17 ] . This study measured changes in root length using CBCT before and after clear aligner intrusion. The results revealed mean resorption of 1.02 mm for mandibular central incisors, 1.11 mm for lateral incisors, and 1.21 mm for canines, indicating that root resorption occurs when clear orthodontic appliances are used to lower the mandibular anterior teeth. Root resorption is a complex biological process influenced by many unknown factors. It usually occurs when the force applied to the root tip exceeds the resistance and repair capacity of the periapical tissues [ 18 ] . Its known influencing factors include genetics, ethnic variation, individual susceptibility, and mechanical loading [ 19 – 22 ] . In addition, root morphology, trauma, and malocclusion types may also affect the extent of root resorption [ 23 , 24 ] . Comparative studies on fixed and invisible orthodontic appliances for correction show that clear aligners result in a lower root resorption prevalence (56.3%; 0.13 ± 0.47 mm) compared to fixed appliances (82.11%; 1.12 ± 1.34 mm) [ 25 ] . In terms of statistical significance and clinical effect, the prevalence of root resorption is lower in the invisible orthodontic appliance group compared to the fixed orthodontic appliance group, with the maxillary incisors and mandibular lateral incisors being the most affected.. confirmed root shortening in the central incisors, lateral incisors, and canines of both the upper and lower jaws after treatment with brace-free clear aligners. Meanwhile, international studies have shown that teeth subjected to greater force experienced significantly more root resorption than those with less force or the control group, particularly when the anterior teeth were pressed in [ 26 ] . 4. Conclsions Root shortening of the mandibular anterior teeth after mandibular anterior intrusion using brace-free clear aligners. The root absorption of the mandibular canines is more than that of the lower central incisor and lateral incisor. Declarations Conflicts of interest All authors have completed and submitted the ICMJE Form for disclosure of potential conflicts of interest, and none were reported. Author credit statement Mingmin Zhu:conceptualization,methodology.Xuejin Yuan:data curation,writing-original draft.Mi Zhao:writing-review.Yanxiao Zhang:editing Funding：Youth project of Wuxi health and wellness committee(Q202463) Statement of informed consent Informed consents were obtained by the patients and reviewed by the ethics committee. Data Availability All data generated or analysed during this study are included in this published article (and its Supplementary Information files). References Bollen AM, Huang G, King G, Hujoel P, Ma T. Activation time and material stiffness of sequential removable orthodontic appliances.Part 1: ability to complete treatment. 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The Curve of Spee and its relation to Vertical Eruption of Teeth among Different Malocclusion Groups[J] . Ilknur Veli,Mehmet Ali Ozturk,Tancan Uysal. American Journal of Orthodontics & Dentofacial Orthopedics . 2014 Krieger E , Drechsler T , Schmidtmann I ,et al.Apical root resorption during orthodontic treatment with aligners? A retrospective radiometric study[J].Head, Face Medicine, 2013, 9.DOI:10.1186/1746-160X-9-21. GayG，RaveraS，CastroflorioT，et al.Root resorptionduring orthodontic treatment with Invisalign®：a radiometric study［J］. ProgOrthod，2017，18（1）：12 Acar A, Canyurek U, Kocaaga M, Erverdi N. Continuous vs. discontinuous force application and root resorption. Angle Orthod. 1999;69(2):159–63. McLaughlin KD. Quantitative determination of root resorption during orthodontic treatment. Am J Orthod. 1964;50(2):143. Neal D. Kravitz, Mazyar Moshiri, Jonathan Nicozisis, Shawn Miller,Mechanical considerations for deep-bite correction with aligners,Seminars in Orthodontics［J］,2020,26(03): 134-138. Shin K. The Invisalign Appliance Could Be an Effective Modality for Treating Overbit Malocclusions Within a Mild to Moderate Range[J]. J Evid Based Dent Pract, 2017, 17(3): 278-280. Clements KM, Bollen AM, Huang G, King G, Hujoel P, Ma T. Activation time and material stiffness of sequential removable orthodontic appliances Part 2 Dental improvements[J]. Am J Orthod Dentofacial Orthop, 2003, 124(5): 502-508. Boyd RL. Surgical-orthodontic treatment of two skeletal Class III patients with Invisalign and fixed appliances[J]. J Clin Orthod, 2005, 39(4): 245-258. Miao L , Junmei Z , Orthodontics D O ,et al.A Finite Element Analysis of the Stress Distribution in Lowering Mandibular Incisor with Removable Orthodontic Appliances[J].Journal of Guizhou Medical University, 2017. Hemanth M, Deoli S, Raghuveer HP, Rani MS, Hegde C, Vedavathi B. Stress Induced in the Periodontal Ligament under Orthodontic Loading (Part I): A Finite Element Method Study Using Linear Analysis[J]. J Int Oral Health, 2015, 7(8): 129-133 Fuss Z, Tsesis I, Lin S. Root resorption–diagnosis, classification and treatment choices based on stimulation factors. Dent Traumatol. 2003;19(4):175–82 Weltman B,Vig KW,Feds HW,et al.Root resorption associated with orthodontic tooth movement:a systematic review[J].Am J Orthod Dento Orthop,2010,137(4):462-476. Linge L,Lnge BO.Patent character sticks and treatment variables associated with apical root resorption during orthodontic treatment[J].Am J Orthod Dentofac Orthop,1991,99(1):35-43. Wang J,Rousso C,Christensen B,et al. Ethnic differences in the root to crown ratios of the permanent dentition[J].Orthod CranofacRes,2019,22(2):99-104. Hartsfield J,verett ET,awasmi RG.Enetic factors in external apical root resorption and orthodontic treatment[J].CrtRev Oral Bol Med,2004,15(2):115–22. Boyd L.Complex Orthodontic treatment sign new root color he invisalign appliance[J]lin orthod,2007,9(2):525–547. Sameshima GT,Sinclair PM.Predicting and preventing root resorption part ID agnostic factors[J].AmJ Orthod DentofacOrthop,2001,119(5):505–510 Li Yuan,Deng Shiyong,Mei Li,et al.Prevalence and severity of apical root resorptionduring orthodontic treatment with clear aligners and fixed appliances: a cone beam computed tomography study[J].Prog Orthod,2020,21(1):1-4. Weltman B, Vig KW, Fields HW, Shanker S, Kaizar EE. Root resorption associated with orthodontic tooth movement: a system atic review . Am J Orthod Dentofacial Orthop. 2010,137(4):462–76. Additional Declarations No competing interests reported. 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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-6835983","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":475655429,"identity":"b0a05ee9-b0b4-4181-9fbb-c1757c925519","order_by":0,"name":"xuejin yuan","email":"","orcid":"","institution":"Wuxi Stomatological Hospital","correspondingAuthor":false,"prefix":"","firstName":"xuejin","middleName":"","lastName":"yuan","suffix":""},{"id":475655430,"identity":"3b63ec9c-760d-43be-9fc2-13952aae5a17","order_by":1,"name":"mingmin 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popularity in orthodontic treatment due to their aesthetic appeal and comfort advantages. Initially limited to mild-to-moderate malocclusions, recent advancements in invisible orthodontic technologies and material properties have expanded their use to more complex cases, enabling improved outcomes\u003csup\u003e[1]\u003c/sup\u003e. Key techniques contributing to this progress include optimized treatment design, attachment composition, and vertical control for intrusion\u003csup\u003e[2]\u003c/sup\u003e. Although there are more reports on the intrusion efficiency of clear aligners, studies examining changes in the root length of lower anterior/posterior teeth remain scarce. Conventional clinical techniques for lowering anterior teeth, such as bite plates, reverse-curve archwires, and utility arches, often cause labial inclination\u003csup\u003e[3]\u003c/sup\u003e. The segmented arch technique introduced by Burstone in 1970 helps intrude mandibular incisors and level the SPEE curve\u003csup\u003e[4]\u003c/sup\u003e. Compared to fixed braces, brace-free clear aligners cover the entire tooth surface, allowing the intrusive force to be applied closer to the teeth\u0026rsquo;s center of resistance. This enables all incisors to move more deeply along their longitudinal axis. Studies indicate that the clear aligner techniques tend to result in a near-bodily movement, achieving up to 47% intrusion efficiency for mandibular incisors\u003csup\u003e[5]\u003c/sup\u003e. Research by Song et al. (2018) found that the intrusion efficiency for mandibular lateral incisors is highest at 54.6%, followed by mandibular central incisors and mandibular canines at 48.1% and 42.4%, respectively\u003csup\u003e[6]\u003c/sup\u003e. Patients undergoing treatment with the brace-free clear aligner technique effectively reduced deep overbite due to their lowered mandibular anterior teeth\u003csup\u003e[7]\u003c/sup\u003e. However, tooth intrusion also tends to increase root resorption, which can be classified into three degrees: (1) Mild\u0026zwnj;: the root shortening is less than 2 mm or the change of the root-crown length ratio is less than 10%. (2) \u0026zwnj;Moderate\u0026zwnj;: the root shortening is equal to or more than 2 mm but less than 1/3 of the original length, or the change of the root-crown length ratio is between 10% and 20%. (3) \u0026zwnj;Severe\u0026zwnj;: the root shortening is more than 1/3 of the original length, or the change of the root-crown length ratio is more than 20%\u003csup\u003e［\u003c/sup\u003e\u003csup\u003e8\u003c/sup\u003e\u003csup\u003e，\u003c/sup\u003e\u003csup\u003e9\u003c/sup\u003e\u003csup\u003e］\u003c/sup\u003e. Root resorption is influenced by several factors, including patient age, treatment duration, malocclusion type, and force application. Studies indicate that intermittent force application tends to reduce or even prevent root resorption\u003csup\u003e[10]\u003c/sup\u003e. Due to their feature of being removable, clear aligners deliver intermittent forces, which may contribute to reduced root resorption and better periodontal health compared to continuous forces. Although histological studies report that root resorption incidence with orthodontic treatment exceeds 90%\u003csup\u003e[11]\u003c/sup\u003e, radiographic measurements tend to show slightly lower rates. This study evaluates changes in root length of mandibular anterior teeth before and after clear aligner intrusion using the CBCT technique and investigates possible factors influencing root resorption.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e"},{"header":"‌1. Basic Information and Methods","content":"\u003cp\u003e‌1.1 Patients: A total of 20 adult patients (7 males and 13 females) underwent orthodontic treatment at the Orthodontic Department of Wuxi Stomatological Hospital between January 2019 and December 2023. All the patients were aged 18 to 41 years old, with a mean age of 26.60\u0026nbsp;±\u0026nbsp;6.66 years. They were all treated using full-mouth orthodontic correction with brace-free, clear aligner-based invisible appliances. The frog-jump technique was used to intrude the mandibular anterior teeth. CBCT scans were obtained before and after treatment.\u003c/p\u003e\n\u003cp\u003eEligibility requirements:‌\u003c/p\u003e\n\u003cp\u003e1. Having all the mandibular anterior teeth.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e2. No extractions performed during orthodontic treatment.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e3. Healthy periodontal tissues with no significant root or alveolar bone resorption.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e4. Aged above 18 years.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e5. Exclusive use of clear aligners throughout the treatment period.\u003c/p\u003e\n\u003cp\u003e‌Exclusions:‌\u003c/p\u003e\n\u003cp\u003e1. Presence of radiographically diagnosed pulpal or periapical lesions in mandibular anterior teeth, or a history of root canal treatment.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e2. Clinical signs of periodontitis affecting anterior teeth (e.g., clinical attachment loss) or alveolar bone resorption (CEJ-BC distance \u0026gt;2 mm) on radiographic evaluation.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e3. Abnormalities in the number, morphology, or eruption of mandibular anterior teeth.\u003c/p\u003e\n\u003cp\u003e4. Having undergone orthodontic treatment.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e5. Suffering from systemic diseases that affect bone metabolism or dental health.\u003c/p\u003e\n\u003cp\u003e‌1.2 Research Methods‌\u003c/p\u003e\n\u003cp\u003eAll patients underwent lateral cephalogram and CBCT imaging (KaVo Dental Gmbh, Germany) at the Radiology Department of Wuxi Stomatological Hospital. The scanning parameters were shown as follows: Voltage: 120 kV; current: 5.0 mA; slice thickness: 0.3 mm; and exposure time: 20 s. During imaging, patients were positioned with their mandibles stabilized on the chin rest, their facial midline perpendicular to the ground and aligned with the scanner’s central axis, and their occlusal plane parallel to the ground. All scans were taken by the same radiologist, strictly adhering to standardized protocols and using the built-in NNT Viewer software.\u003c/p\u003e\n\u003cp\u003eCBCT measurements were conducted as follows: Images were reconstructed in the MPR window using the editing function. The horizontal cross-section of the target tooth was selected and aligned with its cervical part. The sagittal plane was then chosen to bisect the mesiodistal dimension of the tooth and adjusted to pass through its long axis. Using the software’s measurement function, the required distances were measured according to the prompts. Next, the target tooth in the mandibular anterior tooth region was positioned on the horizontal plane, adjusting the section so that the sagittal section traversed the maximum buccolingual surface (Figure 1). The coronal longitudinal section was set at an angle to traverse the cusp and root tip (Figure 2). The sagittal longitudinal section was finely adjusted to also pass through the cusp and root tip (Figure 3). Repeated positioning and adjustments were performed to confirm the optimal sagittal buccolingual cross-section. All measurements were taken using the built-in NNT Viewer software. To minimize errors, each parameter was measured three times, and their mean value was used for analysis.\u003c/p\u003e\n\u003cp\u003e‌1.3 Measurement Parameters‌\u003c/p\u003e\n\u003cp\u003e(1) Root length: Distance between Point 2 and Point 5 (Figure 4).\u003c/p\u003e\n\u003cp\u003e(2) L-MP (mm): Vertical distance from the incisal edge of the mandibular anterior tooth to the mandibular plane. The difference between pre-and post-treatment values represents the actual intrusion magnitude(‌Figure 5).\u003c/p\u003e\n\u003cp\u003e(3) L-MP (°): Angle between the long axis of the mandibular anterior tooth and the mandibular plane. The difference between pre-and post-treatment values reflects changes in labial inclination(‌Figure 5).\u003c/p\u003e\n\u003cp\u003e(4) Designed intrusion magnitude: Crown intrusion (I) values obtained from the ClinCheck tooth movement table (mm).\u003c/p\u003e\n\u003cp\u003eDeclaration that the patient signed the informed consent form and was reviewed by the Ethics Committee of Wuxi Stomatological Hospital (Ethics number: 025061101).\u003c/p\u003e\n\u003cp\u003eDeclaration that all experiments were performed in accordance with relevant guidelines and regulations.\u003c/p\u003e\n\u003cp\u003e‌1.4 Statistical Analysis‌\u003c/p\u003e\n\u003cp\u003eStatistical analysis was conducted using SPSS 22.0 software. Paired t-tests were used to compare pre- and post-treatment measurements, with statistical significance set at\u0026nbsp;p\u0026nbsp;\u0026lt; 0.05.\u003c/p\u003e\n\u003cp\u003e‌Table 4: Changes in root length of mandibular anterior teeth (mm)‌\u003c/p\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePre-treatment\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePost-treatment\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePre-Post Difference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eT-value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eP-value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eL1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e11.29±0.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e10.27±0.81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e9.074\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.000**\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eL2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e12.10±1.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e10.99±0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e8.360\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.000**\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eL3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e14.23±1.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e13.02±1.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e8.164\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.000**\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e‌\u0026nbsp;P\u0026lt;0.05\u003csup\u003e*\u003c/sup\u003e, p\u0026lt;0.01\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003e‌Table 5: Comparison of actual vs. designed intrusion magnitude in mandibular anterior teeth (mm)\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"565\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eActual Intrusion\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eDesigned Intrusion\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eDifference (Designed - Actual)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eT-value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eP-value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eL1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e1.78±0.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e3.34±1.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e1.56±0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e6.310\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e0.004**\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eL2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e1.73±0.81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e3.27±1.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e1.54±0.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e8.664\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e0.000**\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eL3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e0.95±0.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e2.44±0.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e1.49±0.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e10.587\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e0.000**\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e‌\u0026nbsp;P\u0026lt;0.05\u003csup\u003e*\u003c/sup\u003e, p\u0026lt;0.01\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003e‌Table 6: Changes in L/MP angle of mandibular anterior teeth (°)\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"538\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003ePre-treatment\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003ePost-treatment\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eDifference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eT-value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eP-value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eL1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e92.86±6.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e93.17±4.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e3.76±4.81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e0.170\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e0.868\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eL2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e92.46±6.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e94.10±3.14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e3.48±4.52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e0.960\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e0.352\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eL3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e94.48±4.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e95.51±2.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e2.08±1.77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e0.918\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e0.373\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp; P\u0026lt;0.05*, p\u0026lt;0.01**\u003c/p\u003e"},{"header":"2. Results","content":"\u003cp\u003eIn this study, the average root length of mandibular central incisors before treatment was (11.29 ± 0.98) mm. After intrusion, it decreased to (10.27 ± 0.81) mm, showing a statistically significant difference (P \u0026lt; 0.01). Similarly, the average length of mandibular lateral incisors before treatment was (12.10 ± 1.21) mm. This length reduced to (10.99 ± 0.99) mm after intrusion, showing a statistically significant difference (P \u0026lt; 0.01). The mandibular canines had an average length of (14.23 ± 1.47) mm before treatment. This length reduced to (13.02 ± 1.45) mm post-intrusion, showing a statistically significant difference (P \u0026lt; 0.01)(‌Table 4). All mandibular anterior teeth demonstrated statistically significant intrusion differences (P \u0026lt; 0.01), accompanied by root shortening and absorption. While different degrees of intrusion were observed across all mandibular anterior teeth (P \u0026lt; 0.01)(‌Table 5).A slight labial inclination was noted but was not statistically significant (P \u0026gt; 0.05)(‌Table 6).\u003c/p\u003e"},{"header":"3. Discussion","content":"\u003cp\u003eA deep overbite is a relatively common type of malocclusion. Its correction usually involves principles such as labial inclination of the anterior teeth, intrusion of the anterior teeth, extrusion of the posterior teeth, etc. When intruding the anterior teeth, the patient’s gingival display during smiling should be taken into account. Since adults lack growth potential and extrusion of posterior molars often tends to relapse, intrusion of the mandibular anterior teeth is a more commonly chosen option to improve deep overbite. Bite plates, reverse curve arches, intrusion auxiliary arches, and segmental arches are usually used for intruding mandibular anterior teeth. However, these methods require precise archwire bending, can reduce patient comfort, and demand excellent patient compliance.\u003c/p\u003e\u003cp\u003eWith the advancement of implant anchorage techniques, mini-implants can achieve effective intrusion. However, their placement is invasive, carries risks of loosening or failure, and often faces patient resistance. In clear aligner treatment of deep overbite cases, mandibular anterior intrusion mimics the mechanism of reverse curve arches used in fixed appliances\u003csup\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e. As a force-efficient system, clear aligners can intrude teeth without auxiliary devices. Multiple international studies have demonstrated the high predictability of deep overbite correction with clear aligners, consistently reporting favorable outcomes in mandibular anterior intrusion\u003csup\u003e[\u003cspan additionalcitationids=\"CR14\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e–\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/sup\u003e. Therefore, when treating deep overbite with clear aligners, clinicians should prioritize anterior intrusion to open the bite and fully leverage the system's advantages.\u003c/p\u003e\u003cp\u003eRoot resorption is one of the most common complications in orthodontics. It has a multifactorial etiology that involves biological variability, genetic predisposition, and mechanical factors. Its mechanism involves two phases: initial surface damage exposing mineralized tissue, followed by multinucleated cell colonization triggering resorption. Without sustained stimulation, cementum-like repair occurs within 2 to 3 weeks. However, persistent inflammation can cause deeper damage to the dentin and lead to radiographically detectable resorption. Finite element analyses simulating clear aligner intrusion of mandibular anterior teeth with varying labial inclinations show that the greater the deviation of the labial inclination from the normal value of the mandibular anterior teeth, the greater the stress of the tooth root on the labial and lingual sides. These stress concentration areas increase the risk of root resorption. Therefore, when performing intrusion of mandibular anterior teeth, it is important not only to consider the amount of intrusion but also to pay attention to changes on the labial and lingual sides of the teeth to prevent root resorption\u003csup\u003e[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eThis study measured changes in root length using CBCT before and after clear aligner intrusion. The results revealed mean resorption of 1.02 mm for mandibular central incisors, 1.11 mm for lateral incisors, and 1.21 mm for canines, indicating that root resorption occurs when clear orthodontic appliances are used to lower the mandibular anterior teeth. Root resorption is a complex biological process influenced by many unknown factors. It usually occurs when the force applied to the root tip exceeds the resistance and repair capacity of the periapical tissues\u003csup\u003e[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e. Its known influencing factors include genetics, ethnic variation, individual susceptibility, and mechanical loading\u003csup\u003e[\u003cspan additionalcitationids=\"CR20 CR21\" citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e–\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/sup\u003e. In addition, root morphology, trauma, and malocclusion types may also affect the extent of root resorption\u003csup\u003e[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eComparative studies on fixed and invisible orthodontic appliances for correction show that clear aligners result in a lower root resorption prevalence (56.3%; 0.13 ± 0.47 mm) compared to fixed appliances (82.11%; 1.12 ± 1.34 mm)\u003csup\u003e[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]\u003c/sup\u003e. In terms of statistical significance and clinical effect, the prevalence of root resorption is lower in the invisible orthodontic appliance group compared to the fixed orthodontic appliance group, with the maxillary incisors and mandibular lateral incisors being the most affected.. confirmed root shortening in the central incisors, lateral incisors, and canines of both the upper and lower jaws after treatment with brace-free clear aligners. Meanwhile, international studies have shown that teeth subjected to greater force experienced significantly more root resorption than those with less force or the control group, particularly when the anterior teeth were pressed in\u003csup\u003e[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e"},{"header":"4. Conclsions","content":"\u003col\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eRoot shortening of the mandibular anterior teeth after mandibular anterior intrusion using brace-free clear aligners.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eThe root absorption of the mandibular canines is more than that of the lower central incisor and lateral incisor.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003c/ol\u003e"},{"header":"Declarations","content":"\u003cp\u003eConflicts of interest\u003c/p\u003e\n\u003cp\u003eAll authors have completed and submitted the ICMJE Form for disclosure of potential conflicts of interest, and none were reported.\u003c/p\u003e\n\u003cp\u003eAuthor credit statement\u003c/p\u003e\n\u003cp\u003eMingmin Zhu:conceptualization,methodology.Xuejin Yuan:data curation,writing-original draft.Mi Zhao:writing-review.Yanxiao Zhang:editing\u003c/p\u003e\n\u003cp\u003eFunding：Youth project of Wuxi health and wellness committee(Q202463)\u003c/p\u003e\n\u003cp\u003eStatement of informed consent\u003c/p\u003e\n\u003cp\u003eInformed consents were obtained by the patients and reviewed by the ethics committee.\u003c/p\u003e\n\u003cp\u003eData Availability\u003c/p\u003e\n\u003cp\u003eAll data generated or analysed during this study are included in this published article (and its Supplementary Information files).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eBollen AM, Huang G, King G, Hujoel P, Ma T. Activation time and material stiffness of sequential removable orthodontic appliances.Part 1: ability to complete treatment. Am J Orthod DentofacialOrthop 2003;124:496-501\u003c/li\u003e\n\u003cli\u003eZhang L , Gong B , Xie X ,et al.The effectiveness of clear aligners in levelling the curve of Spee and related maxillofacial factors in patients with a deep overbite[J].AUSTRALASIAN ORTHODONTIC JOURNAL, 2024, 40(1):9.DOI:10.2478/aoj-2024-0015.\u003c/li\u003e\n\u003cli\u003eFattahi, H.; Pakshir, H.; Afzali, B.N.; Shahian, J.S. Skeletal and dentoalveolar features in patients with deep overbite malocclusion. J. Dent. (Tehran) 2014, 11, 629\u0026ndash;638.\u003c/li\u003e\n\u003cli\u003eBurstone, C.R. Deep overbite correction by intrusion. Am. J. Orthod. 1977, 72, 1\u0026ndash;22.\u003c/li\u003e\n\u003cli\u003eGabriele Ｒ，Simone P，Tommaso C，et al．Systematic Ｒeview Article Ef-ficacy of clear aligners in controlling orthodontic tooth movement: Asystematic revie［J］．Angle Orthod，2015，85( 5) : 881－889．\u003c/li\u003e\n\u003cli\u003eSong B, Wang P, Li D ,Tian J. Gu Zexu.A clinical study evaluating the efficiency of intrusion in anterior teeth by clear aligner technique[J].chinese journal of stomatology, 2018,25(04):186-190.\u003c/li\u003e\n\u003cli\u003eThe Curve of Spee and its relation to Vertical Eruption of Teeth among Different Malocclusion Groups[J] . Ilknur Veli,Mehmet Ali Ozturk,Tancan Uysal. American Journal of Orthodontics \u0026amp; Dentofacial Orthopedics . 2014\u003c/li\u003e\n\u003cli\u003eKrieger E , Drechsler T , Schmidtmann I ,et al.Apical root resorption during orthodontic treatment with aligners? A retrospective radiometric study[J].Head, Face Medicine, 2013, 9.DOI:10.1186/1746-160X-9-21.\u003c/li\u003e\n\u003cli\u003eGayG，RaveraS，CastroflorioT，et al.Root resorptionduring orthodontic treatment with Invisalign\u0026reg;：a radiometric study［J］. ProgOrthod，2017，18（1）：12\u003c/li\u003e\n\u003cli\u003eAcar A, Canyurek U, Kocaaga M, Erverdi N. Continuous vs. discontinuous force application and root resorption. Angle Orthod. 1999;69(2):159\u0026ndash;63.\u003c/li\u003e\n\u003cli\u003eMcLaughlin KD. Quantitative determination of root resorption during orthodontic treatment. Am J Orthod. 1964;50(2):143.\u003c/li\u003e\n\u003cli\u003eNeal D. Kravitz, Mazyar Moshiri, Jonathan Nicozisis, Shawn Miller,Mechanical considerations for deep-bite correction with aligners,Seminars in Orthodontics［J］,2020,26(03): 134-138.\u003c/li\u003e\n\u003cli\u003eShin K. The Invisalign Appliance Could Be an Effective Modality for Treating Overbit Malocclusions Within a Mild to Moderate Range[J]. J Evid Based Dent Pract, 2017, 17(3): 278-280.\u003c/li\u003e\n\u003cli\u003eClements KM, Bollen AM, Huang G, King G, Hujoel P, Ma T. Activation time and material stiffness of sequential removable orthodontic appliances Part 2 Dental improvements[J]. Am J Orthod Dentofacial Orthop, 2003, 124(5): 502-508.\u003c/li\u003e\n\u003cli\u003eBoyd RL. Surgical-orthodontic treatment of two skeletal Class III patients with Invisalign and fixed appliances[J]. J Clin Orthod, 2005, 39(4): 245-258.\u003c/li\u003e\n\u003cli\u003eMiao L , Junmei Z , Orthodontics D O ,et al.A Finite Element Analysis of the Stress Distribution in Lowering Mandibular Incisor with Removable Orthodontic Appliances[J].Journal of Guizhou Medical University, 2017.\u003c/li\u003e\n\u003cli\u003eHemanth M, Deoli S, Raghuveer HP, Rani MS, Hegde C, Vedavathi B. Stress Induced in the Periodontal Ligament under Orthodontic Loading (Part I): A Finite Element Method Study Using Linear Analysis[J]. J Int Oral Health, 2015, 7(8): 129-133\u003c/li\u003e\n\u003cli\u003eFuss Z, Tsesis I, Lin S. Root resorption\u0026ndash;diagnosis, classification and treatment choices based on stimulation factors. Dent Traumatol. 2003;19(4):175\u0026ndash;82\u003c/li\u003e\n\u003cli\u003eWeltman B,Vig KW,Feds HW,et al.Root resorption associated with orthodontic tooth movement:a systematic review[J].Am J Orthod Dento Orthop,2010,137(4):462-476.\u003c/li\u003e\n\u003cli\u003eLinge L,Lnge BO.Patent character sticks and treatment variables associated with apical root resorption during orthodontic treatment[J].Am J Orthod Dentofac Orthop,1991,99(1):35-43.\u003c/li\u003e\n\u003cli\u003eWang J,Rousso C,Christensen B,et al. Ethnic differences in the root to crown ratios of the permanent dentition[J].Orthod CranofacRes,2019,22(2):99-104.\u003c/li\u003e\n\u003cli\u003eHartsfield J,verett ET,awasmi RG.Enetic factors in external apical root resorption and orthodontic treatment[J].CrtRev Oral Bol Med,2004,15(2):115\u0026ndash;22.\u003c/li\u003e\n\u003cli\u003eBoyd L.Complex Orthodontic treatment sign new root color he invisalign appliance[J]lin orthod,2007,9(2):525\u0026ndash;547.\u003c/li\u003e\n\u003cli\u003eSameshima GT,Sinclair PM.Predicting and preventing root resorption part ID agnostic factors[J].AmJ Orthod DentofacOrthop,2001,119(5):505\u0026ndash;510\u003c/li\u003e\n\u003cli\u003eLi Yuan,Deng Shiyong,Mei Li,et al.Prevalence and severity of apical root resorptionduring orthodontic treatment with clear aligners and fixed appliances: a cone beam computed tomography study[J].Prog Orthod,2020,21(1):1-4.\u003c/li\u003e\n\u003cli\u003eWeltman B, Vig KW, Fields HW, Shanker S, Kaizar EE. Root resorption associated with orthodontic tooth movement: a system atic review . Am J Orthod Dentofacial Orthop. 2010,137(4):462\u0026ndash;76.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Aligners, CBCT, root length, lower anterior","lastPublishedDoi":"10.21203/rs.3.rs-6835983/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6835983/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eObjective: To evaluate the effects on root length and root resorption of the lower anterior teeth after intrusion with clear aligners in adults with deep overbite, using three-dimensional imaging via cone-beam computed tomography (CBCT).\u003c/p\u003e\n\u003cp\u003eMethods: From January 2019 to December 2023, twenty adult patients treated at the orthodontics department with clear aligners designed specifically for the intrusion of the lower anterior teeth were selected for this study. CBCT scans were taken before and after treatment to measure changes in the root length of the lower anterior teeth, and the data were analyzed statistically.\u003c/p\u003e\n\u003cp\u003eResults: The change in root length of the mandibular central incisors, lateral incisors, and canines was statistically significant (P\u0026lt;0.01) in all cases.\u003c/p\u003e\n\u003cp\u003eConclusion: 1.After the use of clear aligners for the intrusion of the lower anterior teeth, a reduction in root length of the lower anterior teeth was observed (P\u0026lt;0.01). 2.The root absorption of the mandibular canines is more than that of the lower central incisor and lateral incisor.\u003c/p\u003e","manuscriptTitle":"Evaluate the Changes in Root Length of the Lower Anterior Teeth after Intrusion with Clear Aligners","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-06-30 08:44:42","doi":"10.21203/rs.3.rs-6835983/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-07-30T05:12:11+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-07-26T12:57:57+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-07-17T09:57:07+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"272614442013171181190987737141328245729","date":"2025-07-13T18:40:03+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"212555729399233776555649761761962962174","date":"2025-06-26T09:51:46+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-06-24T09:17:23+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-06-19T02:36:11+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-06-17T06:44:51+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-06-14T04:10:16+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2025-06-06T09:54:51+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"218304fb-84eb-41f5-b949-34cbbc97fb5c","owner":[],"postedDate":"June 30th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":50507341,"name":"Biological sciences/Biophysics"},{"id":50507342,"name":"Health sciences/Medical research"}],"tags":[],"updatedAt":"2025-09-26T06:08:53+00:00","versionOfRecord":[],"versionCreatedAt":"2025-06-30 08:44:42","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6835983","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6835983","identity":"rs-6835983","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}