Three-dimensional Spatiotemporal Analysis of Condylar Remodeling After Conservative Treatment of Pediatric Mandibular Condylar Sagittal Fractures

Three-dimensional Spatiotemporal Analysis of Condylar Remodeling After Conservative Treatment of Pediatric Mandibular Condylar Sagittal Fractures | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Three-dimensional Spatiotemporal Analysis of Condylar Remodeling After Conservative Treatment of Pediatric Mandibular Condylar Sagittal Fractures Mingyan Li, Meng Liu, Shuo Chen, Yang He This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8806987/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 11 You are reading this latest preprint version Abstract Objective This study investigated condylar remodeling and the role of the temporomandibular joint (TMJ) disc in growing patients with sagittal fractures of the mandibular condyle (SFMC) treated conservatively. Materials and methods A retrospective analysis was performed on 28 children (aged 4–12 years) with 43 SFMCs using three-dimensional models reconstructed from computed tomography (CT) and magnetic resonance imaging (MRI) obtained before treatment and at 3, 6, and 12 months after treatment. To evaluate condylar remodeling and its relationship with the articular disc, multimodal image registration was applied to fuse CT and MRI datasets. Results The results demonstrated a significant decrease in condylar volume from pre-treatment to 3 months post-treatment (Phase P1, P = 0.006). No significant change was observed between 3 and 6 months (Phase P2, P = 0.977), followed by a significant increase from 6 months to 1 year (Phase P3, P = 0.005). Bone formation predominantly occurred in regions covered by the articular disc, with significant differences in root mean square (RMS) values between disc-covered and non-disc-covered areas (P = 0.012). Conclusions These findings indicate that condylar remodeling is most active during the first 3 months following conservative treatment of pediatric SFMC and that the TMJ disc plays a critical role in this process. Clinical relevance: Clinical prognostic studies on sagittal condylar fractures in children can assist clinicians in more accurately assessing fracture severity, selecting the most appropriate treatment strategies, reducing the incidence of complications, and ultimately improving overall treatment outcomes in pediatric patients. Children Mandibular condyle Sagittal fracture Condylar remodeling Articular disc Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Sources of support This study was supported by the National Key Research and Development Program of China (Grant No. 2023YFC3011901), Capital’s Funds for Health Improvement and Research (Grant No. 2022-4-4109), and the Beijing Natural Science Foundation (Grant Nos. L242136 and L252201). 1. Introduction Mandibular fractures represent the most common type of maxillofacial fracture in children [ 1 , 2 ], with the condyle being the most frequently affected site, accounting for approximately 25%–80% of all mandibular fractures [ 1 – 5 ]. In growing children, the condyle functions as a primary growth center of the mandible, and inappropriate management may result in malocclusion, TMJ dysfunction, mandibular developmental disturbances, and even ankylosis. Previous studies have demonstrated that children younger than 12 years exhibit a strong capacity for condylar bone remodeling and growth [ 5 ]. Conservative treatment strategies, including early functional exercises, occlusal splints, soft diets, and orthodontic interventions [ 6 ], have been shown to effectively restore condylar height and normal TMJ function [ 7 , 8 ]. Owing to the potential risks associated with surgical intervention, such as secondary condylar injury, nerve damage, and scarring, conservative treatment remains the preferred therapeutic approach among most clinicians [ 9 , 10 ]. As a critical component of the TMJ, the morphology of the mandibular condyle is closely associated with joint stability and function. Previous evaluations of condylar remodeling have largely relied on clinical findings and two-dimensional (2D) imaging, which lack longitudinal and dynamic observations [ 11 – 13 ]. Advances in three-dimensional reconstruction and image registration technologies have enabled more intuitive visualization of condylar remodeling and facilitated the investigation of its spatial changes. Previous research on factors influencing condylar remodeling has primarily focused on fracture patterns and the degree of displacement. In recent years, with the widespread application of magnetic resonance imaging (MRI), increasing attention has been directed toward soft tissue injuries, particularly anterior disc displacement. Animal studies have demonstrated that the articular disc participates in condylar regeneration and mandibular growth [ 14 , 15 ]. Liu et al. [ 16 ] reported that anterior disc displacement and unfavorable condylar remodeling occurred following SFMC in children, suggesting that persistent anterior disc displacement may be associated with increased condylar width and depth and reduced condylar height. These findings indicate a potential influence of the TMJ disc on condylar remodeling. However, clinical assessment of disc displacement relies on MRI, whereas evaluation of condylar remodeling is typically based on CT imaging. The application of multimodal image registration techniques to fuse CT and MRI images allows direct visualization of the spatial relationship between the articular disc and the condyle. Sagittal fractures are characterized by a fracture line that traverses the articular surface and extends obliquely toward the medial aspect of the condylar head or neck, accounting for approximately 9%–29% of all condylar fractures [ 16 ]. In pediatric patients, sagittal fractures are predominantly managed conservatively. Under the traction of the lateral pterygoid muscle, the articular disc typically displaces anteromedially and inferiorly together with the medial condylar fragment. Consequently, this characteristic displacement pattern provides a “natural model” for investigating the dynamic relationship between condylar remodeling and the articular disc [ 16 ]. The aim of this study was to apply multimodal image registration techniques to systematically analyze condylar remodeling patterns in pediatric SFMC following conservative treatment and to investigate the influence of articular disc position on this process. 2. Materials and Methods 2.1 Patients From September 2014 to January 2025, 28 patients (19 males and 9 females; 15 bilateral fractures and 13 unilateral fractures; age range, 4–12 years) with a total of 43 SFMCs were enrolled. The inclusion criteria were as follows: (1) age ≤ 12 years; (2) initial presentation within 2 weeks after injury; (3) confirmed diagnosis of sagittal condylar fracture; (4) treatment with conservative management; and (5) availability of TMJ MRI and spiral CT or cone-beam computed tomography (CBCT) data obtained before treatment and at 3 months, 6 months, or 1 year after treatment. The exclusion criteria included: (1) developmental anomalies or inflammatory diseases (e.g., idiopathic arthritis); (2) dislocation of the ramus stump into the glenoid fossa; and (3) concomitant facial fractures. All patients were treated conservatively. They were instructed to wear occlusal splints and to perform mouth-opening, lateral excursion, and protrusive functional exercises under physician supervision for a minimum of 3 months [2]. Follow-up examinations were conducted at 3 months, 6 months, and 1 year after treatment. Spiral CT or CBCT scans were obtained at all follow-up time points, while MRI examinations were additionally performed at the 6-month and 1-year evaluations. 2.2 Image Acquisition Spiral computed tomography (CT) examinations (tube voltage, 76–80 kV; tube current, 4.2–6.0 mA; field of view [FOV], 6 × 6 cm) were performed with patients in the intercuspal position (ICP). The slice thickness was 0.48 mm. CBCT examinations (3D Accuitomo, J. Morita Mfg. Corp., Japan; 90 kV; 5 mA; FOV, 4 × 4 cm or 6 × 6 cm; voxel size, 0.25 × 0.25 × 0.25 mm) were also conducted in the intercuspal position. Temporomandibular joint (TMJ) MRI examinations (GE 1.5 T, USA; dual coil) were performed using proton density (PD)-weighted sequences (TR, 3000 ms; TE, 12 ms), with oblique sagittal localizers oriented perpendicular to the long axis of the condyle. The slice thickness was 2.5 mm. 2.3 Multimodal Image Registration Reconstruction of three-dimensional (3D) models of the condyle and articular disc: Original Digital Imaging and Communications in Medicine (DICOM) files from spiral CT/CBCT and MRI were imported into Mimics Medical 21.0 software. Three-dimensional models of the condyle and articular disc were reconstructed using threshold-based segmentation followed by manual correction (Fig. 1A, B). Color map deviation analysis of 3D condylar models: All 3D condylar models were exported in STL format and imported into Geomagic Studio 2014 software. The coronoid process and sigmoid notch regions were designated as reference regions using the “Select” tool. Based on these reference regions, the “Best Fit Alignment” function was applied to accurately superimpose the condylar models. Color map deviation analysis was then performed between adjacent time points (Fig. 1C). Reconstruction of fused 3D condyle–disc models using multimodal image registration: Three-dimensional condylar models (STL format) were imported into the Mimics project files containing the 3D articular disc models. At least three MRI slices displaying clear articular disc and condylar structures were selected, and the 3D condylar model was aligned with the corresponding condylar contours on these slices until optimal matching was achieved (Fig. 1D). Key steps in constructing models and analyzing bone remodeling using multimodal image registration technology: (A) Step 1 : Reconstruction of the 3D articular disc model from MRI data (B) Step 2 : Reconstruction of the 3D condylar model from CT/CBCT data (C) Step 3 : Precise registration of the articular disc and condyle models to form the disc-condyle complex model (D) Step 4 : Defining the sigmoid notch and coronoid process to align the 3D models, followed by color map deviation analysis of condylar models at different time points 2.4 Evaluation of 3D Condyle Models Condylar remodeling was evaluated across three phases: Phase P1 (pre-treatment to 3 months), Phase P2 (3 to 6 months), and Phase P3 (6 months to 1 year). According to the location of the fracture line, the condyle was divided into a proximal segment (ramus stump) and a distal segment (condylar fragment) (Fig. 2). 2.4.1 Evaluation of Condylar Remodeling Condylar volume was quantified by defining a reference plane tangent to the lowest point of the sigmoid notch using Mimics Research 21.0, and the volume above this plane was calculated (Fig. 3). Three-dimensional condylar models from consecutive time points were registered, and root mean square (RMS) deviation values were calculated. The spatial distribution of bone resorption and bone formation was classified into four categories: involvement of the proximal segment only, involvement of the distal segment only, involvement of both proximal and distal segments, and no obvious bone resorption or formation (Fig. 4). The number of cases in each category was recorded at 3 months, 6 months, and 1 year after treatment. 2.4.2 Evaluation of Proximal and Distal Segment Remodeling The volumes of the proximal and distal segments were measured separately to assess remodeling activity. Remodeling patterns were classified into four types: bone formation dominant, bone resorption dominant, balanced bone formation and resorption, and no obvious remodeling (Fig. 5). The number of cases corresponding to each pattern was recorded. 2.5 Evaluation of 3D Condyle–Disc Models Displacement of the fracture fragment and articular disc was evaluated before and after treatment [16]. When the majority of the condylar fracture fragment or articular disc was located within the glenoid fossa, it was defined as non-displaced; when the majority was located outside the glenoid fossa, it was defined as displaced (Fig. 6). The articular disc was projected onto the condylar surface in a superior view to delineate disc-covered and non-disc-covered areas (Fig. 7). Following registration of pre- and post-treatment models, surface deviation was assessed using color mapping, and RMS deviation values were calculated separately for each area. 2.6 Statistical Methods Statistical analyses were conducted using SPSS software (version 26.0). Paired-samples t-tests were used to evaluate changes in volume and RMS deviation of the affected condyle and to compare specific subregions (proximal versus distal segments and disc-covered versus non-disc-covered areas). For the contralateral condyle, independent-samples t-tests or Mann–Whitney U tests were applied depending on data distribution. Categorical variables were analyzed using Fisher’s exact test. Statistical significance was defined as a P value < 0.05. 3. Results The study cohort included 28 children (19 males and 9 females; mean age, 8.29 ± 2.19 years) with 15 bilateral and 13 unilateral condylar fractures. Clinically, fracture healing proceeded uneventfully, and no significant complications were observed during the follow-up period. Based on the availability of serial imaging data, cases were grouped into three intervals: pre-treatment to 3 months (8 patients, 13 joints), 3 to 6 months (6 patients, 10 joints), and 6 months to 1 year (11 patients, 18 joints). Paired MRI data were available for 9 patients (15 joints). In total, 76 three-dimensional condylar models were reconstructed across all follow-up time points (3 months, n = 20; 6 months, n = 29; 1 year, n = 27), together with 15 fused condyle–disc models. The registration process demonstrated high accuracy, with a RMS error of 0.42 mm. 3.1 Results of 3D Condyle Models 3.1.1 Condylar Remodeling As summarized in Table 1, the volume of the fractured condyle showed a significant reduction during Phase P1 (P = 0.006) and a significant increase during Phase P3 (P = 0.005), whereas no statistically significant change was observed during Phase P2 (P = 0.977). These results indicate that condylar remodeling was characterized predominantly by bone resorption within the first 3 months after treatment, followed by a shift toward bone formation after 6 months. In contrast, the contralateral condyle remained volumetrically stable throughout the study period, with no significant differences observed across the three phases (P1, P = 0.183; P2, P = 0.173; P3, P = 0.833). Sequential surface deviation analysis revealed a gradual decline in remodeling activity over time. The RMS deviation in Phase P1 was significantly higher than that in Phase P2 (P = 0.024), which was in turn significantly higher than that in Phase P3 (P = 0.020). These findings indicate that condylar remodeling activity was most pronounced in the early post-treatment period and progressively diminished thereafter. Table 1 Changes in Volume and RMS of the Affected Condyle at Different Post-Treatment Intervals(* P<0.05; ** P<0.001) As detailed in Tables 2 and 3, no statistically significant differences were observed in the overall distribution of bone formation and resorption on the fractured condyle over time (P = 0.059; P = 0.063). Bone resorption was predominantly observed in the proximal segment, with the proportion of affected cases decreasing during the first 6 months. In contrast, bone formation occurred mainly in the distal segment and demonstrated an increasing trend over the same period (Fig. 8). Phase Time piont n Condylar volume(mm 3 ) P-value RMS P-value P1 Pre-treatment 13 1612.77 ± 74.52 0.006 * - - 3 months 1380.95 ± 83.11 - P2 3 months 10 1184.43 ± 71.81 0.977 1.3628 ± 0.45 0.024 * 6 months 1186.61 ± 99.15 0.9773 ± 0.45 P3 6 months 18 1540.84 ± 98.21 0.005 * 1.6438 ± 0.85 0.020 * 1 year 1705.24 ± 111.54 1.1967 ± 0.32 Table 2 Spatial Distribution of Bone Formation at Different Post-Treatment Time Points Time piont distal segment only proximal segment only both proximal and distal segments no obvious formation P-value 3 months(n = 20) 12(60%) 1(5%) 3(15%) 4(20%) 0.059 6 months(n = 29) 14(48.3%) 0 14(48.3%) 1(3.4%) 1 year(n = 27) 12(44.4%) 2(7.4%) 10(37%) 3(11.1%) Table 3 Spatial Distribution of Bone Resorption at Different Post-Treatment Time Points bone resorption Time piont distal segment only proximal segment only both proximal and distal segments no obvious resorption P-value 3 months(n = 20) 1(5%) 9(45%) 3(15%) 7(35%) 0.063 6 months(n = 29) 0 14(48.3%) 1(3.4%) 14(48.3%) 1 year(n = 27) 1(3.7%) 6(22.2%) 1(3.7%) 19(70.4%) 3.1.2 Proximal and Distal Segment Remodeling As shown in Table 4, during Phase P1, the volume of the proximal segment decreased significantly (P < 0.000), whereas the volume of the distal segment increased significantly (P = 0.014). Quantitatively, the reduction in proximal segment volume (390.83 ± 44.87 mm³) was significantly greater than the increase in distal segment volume (203.48 ± 41.39 mm³) (P = 0.007). As detailed in Table 5 and Fig. 9, the proximal and distal segments exhibited significantly different remodeling patterns (P < 0.000). These results indicate that, during the early post-treatment phase, bone resorption, which predominated in the proximal segment, exceeded bone formation, which predominated in the distal segment. Separate volumetric analyses of the proximal and distal segments at 6 months and 1 year were not feasible because fracture healing rendered the fracture line indistinguishable for three-dimensional segmentation. Table 4 Volumetric Changes in Proximal and Distal Segments at 3 Months Post-Treatment n Proximal segment volume(mm 3 ) P-value Distal segment volume(mm 3 ) P-value Pre-treatment 13 886.01 ± 59.97 0.000 ** 726.76 ± 49.95 0.014 * 3 months 13 495.18 ± 55.25 885.77 ± 43.89 Table 5 Comparison of Remodeling Pattern Types of the Distal and Proximal Segments Post-Treatment remodeling patterns bone formation dominant bone resorption dominant Balanced bone formation and resorption no obvious remodeling P-value distal segment(n = 76) 62(81.6%) 4(5.3%) 4(5.3%) 6(9.7%) 0.000 ** proximal segment(n = 76) 27(35.5%) 30(39.5%) 3(3.9%) 16(21.1%) 3.2 Results of 3D Condyle–Disc Models Following fracture, anterior displacement was observed in 60% (26/43) of the fracture fragments (distal segments) and in 100% (15/15) of the articular discs. After conservative treatment, all fracture fragments and articular discs returned to the glenoid fossa (Fig. 10). Among the 15 reconstructed condyle–disc models, significant bone formation was observed in 93.3% (14/15) of cases. The articular disc was predominantly positioned over the surface of the distal segment (Fig. 11). As shown in Table 6, the RMS deviation values in disc-covered areas differed significantly from those in non-disc-covered areas (P = 0.012). These findings suggest that articular disc coverage may be critical for promoting bone formation. Significant bone formation is observed in the disc-covered area after conservative treatment, while the non-disc-covered area is dominated by bone resorption Table 6 RMS Differences Between Disc-Covered and Non-Disc-Covered Regions n RMS P-value disc-covered area 15 1.8670 ± 0.97 0.012 * non-disc-covered area 15 1.3911 ± 0.54 4. Discussion By integrating three-dimensional reconstruction, multimodal image registration, and color map deviation analysis, this study characterized the remodeling process of pediatric sagittal condylar fractures treated conservatively. The results demonstrated dynamic changes in condylar volume and morphology. Moreover, a significant association was identified between the articular disc and remodeling outcomes, with bone formation predominantly occurring in disc-covered regions, suggesting that the articular disc plays a crucial role in condylar remodeling. This study confirms that condylar healing in pediatric patients involves an active and complex remodeling process rather than simple osseous union of the fracture line, which is consistent with previous reports [ 4 , 11 , 17 ]. Condylar remodeling was most pronounced within the first 3 months after fracture and was characterized by a biphasic pattern of volume change, with an initial reduction followed by expansion. This pattern reflects the physiological sequence of fracture healing, in which osteoclastic resorption precedes osteoblastic bone formation. Despite this regenerative capacity, the mean condylar volume at 1 year remained lower than pre-injury levels. This finding suggests that although substantial adaptive remodeling occurs, complete restoration of pre-injury volume is difficult to achieve, in agreement with Li et al. [ 14 , 15 ], although longer-term follow-up is required to confirm this trend. Notably, the discrepancy between condylar morphology and joint function observed in the present cohort is consistent with the findings of Zhu et al. [ 4 ], who reported satisfactory TMJ function despite varied healing morphologies. Distinct remodeling patterns were identified between the proximal and distal segments. In sagittal fractures, the distal fragment is displaced anteromedially and inferiorly, creating a “bony step” relative to the vertically taller proximal ramus stump. The remodeling process therefore functions to recontour this irregularity and restore articular congruity. This mechanism is consistent with the observations of Li et al. [ 18 ], who reported that the ramus stump undergoes substantial resorption until its height approximates that of the fracture fragment. Temporally, proximal resorption was most pronounced during Phase P1. During Phase P2, a dynamic equilibrium was observed, in which proximal resorption was offset by distal bone formation, resulting in a stable overall condylar volume. After 6 months, bone formation in the distal segment became the dominant process, leading to a net increase in condylar volume. These findings suggest a gradual attenuation of proximal resorption accompanied by sustained long-term bone formation in the distal segment. The observed remodeling pattern appears to be strongly influenced by repositioning of the articular disc. The finding that the displaced disc returned to the glenoid fossa within 3–6 months is consistent with the results reported by Liu et al. [ 16 ]. It is hypothesized that the initial absence of disc coverage over the proximal segment exposes this region to excessive mechanical loading, thereby inducing bone resorption. Conversely, disc repositioning may restore a physiological biomechanical environment conducive to osteogenesis. Animal studies have demonstrated that the articular disc regulates condylar regeneration and mandibular growth in rats [ 15 ]. Disc-mediated alterations in stress distribution on the condylar surface may therefore represent a potential mechanism underlying the predominance of bone formation in disc-covered areas and bone resorption in non-disc-covered areas, although this hypothesis requires further validation through animal experiments. With respect to bone resorption, Li et al. [ 17 ] analyzed two-dimensional images from 93 patients younger than 12 years with intracapsular condylar fractures and reported that abduction of the mandibular ramus was a major contributor to condylar resorption and height reduction, particularly in complex fractures. This factor was not addressed in the present study. Consequently, future investigations should explore whether therapeutic strategies focusing solely on disc repositioning are sufficient for the management of pediatric condylar fractures. Ideally, fracture healing progresses from an early resorptive phase to a later regenerative phase. Specifically, degenerative changes in the mandibular ramus stump predominate initially, followed by regenerative remodeling. This biphasic pattern is consistent with the findings of Liu et al. [ 16 ], who reported that condylar height decreases during the first 6 months after pediatric sagittal fractures but subsequently exhibits a growth rate exceeding that of the unaffected side. Clinically, the early resorptive phase and the associated reduction in condylar height often result in transient exacerbation of mandibular deviation toward the affected side during Phase P2. As bone formation accelerates in the distal segment, this deviation is gradually corrected. Whether such compensatory growth ultimately restores complete symmetry remains to be determined through long-term follow-up studies. This study represents a novel application of multimodal MRI–CT/CBCT registration to visualize three-dimensional condylar remodeling and its spatial relationship with the articular disc in pediatric sagittal fractures. Nevertheless, several limitations should be acknowledged. First, inherent registration errors are unavoidable. Because the pediatric mandible is undergoing active growth, it is difficult to completely distinguish remodeling changes from physiological growth. Future studies should focus on optimizing registration algorithms to minimize this confounding effect. Second, the sample size of the present study was limited, and characterization of condylar remodeling patterns would benefit from validation in larger cohorts. Finally, long-term condylar development was not assessed, and the potential influence of articular disc displacement on long-term outcomes warrants further investigation. In conclusion, this study demonstrates that conservative treatment of sagittal condylar fractures in children younger than 12 years is associated with significant volumetric and morphological remodeling within the first year after injury. Remodeling activity is most pronounced during the initial 3 months and exhibits a distinct spatial pattern, with bone formation predominating in the distal segment and bone resorption occurring primarily in the proximal segment. Furthermore, condylar remodeling is closely associated with the position of the articular disc. Declarations The following additional information is required for submission. 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Competing Interests None Please state any sources of funding for your research This study was supported by National Key Research and Development Program of China (grant No. 2023YFC3011901), Capital’s Funds for Health Improvement and Research (grant No. 2022-4-4109), Beijing Natural Science Foundation (grant No. L242136) and Beijing Natural Science Foundation (grant No. L252201) DOES YOUR STUDY INVOLVE HUMAN OR ANIMALSUBJECTS? Please cross out whichever is not applicable Yes. If your study involves human or animal subjects or records of human patients you MUST have obtained ethical approval. Ethics approval or exemption are required for retrospective studies on patients' records Please state whether Ethical Approval was given, by whom and the relevant Judgement’s reference number This study was approved by the Biomedical Ethics Review Committee of Peking University School and Hospital of Stomatology (Approval No. PKUSSIRB-2025111113). Patient Consent – please state that written patient consent has been obtained to publish clinical photographs. If you have no clinical photographs, please state "not required”. The Journal may request a copy of this consent prior to acceptance Not required. Please add a statement to confirm that all authors have viewed and agreed to the submission All authors have viewed and agreed to the submission. This information must also be inserted into your manuscript under the acknowledgements section prior to the References. References Cooney M, O'connell JE, Vesey JA, Van Eeden S (2020) Non-surgical management of paediatric and adolescent mandibular condyles: A retrospective review of 49 consecutive cases treated at a tertiary referral centre[J]. J Craniomaxillofac Surg 48(7):666–671 Zhao YM, Yang J, Bai RC, Ge LH, Zhang Y (2014) A retrospective study of using removable occlusal splint in the treatment of condylar fracture in children[J]. 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Dent Traumatol 26(3):228–235 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 20 Mar, 2026 Reviews received at journal 23 Feb, 2026 Reviews received at journal 22 Feb, 2026 Reviewers agreed at journal 21 Feb, 2026 Reviews received at journal 19 Feb, 2026 Reviewers agreed at journal 19 Feb, 2026 Reviewers agreed at journal 18 Feb, 2026 Reviewers invited by journal 17 Feb, 2026 Editor assigned by journal 09 Feb, 2026 Submission checks completed at journal 09 Feb, 2026 First submitted to journal 06 Feb, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8806987","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":595176309,"identity":"d1372817-ddc8-4567-90b5-86cda8e61efd","order_by":0,"name":"Mingyan Li","email":"","orcid":"","institution":"Peking University School and Hospital of Stomatology","correspondingAuthor":false,"prefix":"","firstName":"Mingyan","middleName":"","lastName":"Li","suffix":""},{"id":595176312,"identity":"58f81c5e-d6cf-4b8f-b35a-635afcbd1277","order_by":1,"name":"Meng Liu","email":"","orcid":"","institution":"Peking University School and Hospital of Stomatology","correspondingAuthor":false,"prefix":"","firstName":"Meng","middleName":"","lastName":"Liu","suffix":""},{"id":595176313,"identity":"c25a6abc-8f56-4745-98a4-e4d3448428eb","order_by":2,"name":"Shuo Chen","email":"","orcid":"","institution":"Peking University School and Hospital of Stomatology","correspondingAuthor":false,"prefix":"","firstName":"Shuo","middleName":"","lastName":"Chen","suffix":""},{"id":595176314,"identity":"b4dbc1f5-75ee-47b2-8cc6-548d32e95a5c","order_by":3,"name":"Yang He","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA/0lEQVRIie3RMUsDMRTA8TwCueW1tzZc/Q4nDrZcab9Kg2AXZ+ecgUx2v073FW7qnHJwbnW1dLG7w3VTUDBX6uBgrqPQ/KcE3o+QhBCf7x8WSJA9QqhdQvpav48wDKWboPkhjKrLxeNtn2emjRByJIGOkJWjWE5bSFSmLx86EXmeap7hM8bEQL2/c5CuUMO5nomiAjWoB1u8ppLyxfJvMkHQvY4uRcEg3WS4xaE0jHYcBC3hX5bkGqS9yxpjM20nUXOKrODBEnMSUUl/PbsqKtE88g3ybKWcd0EMdpu3++QiV087+5XjSRiqVb13kEPAfm9ly3zT5wkzPp/Pd759AwJ/VCfuPNkRAAAAAElFTkSuQmCC","orcid":"","institution":"Peking University School and Hospital of Stomatology","correspondingAuthor":true,"prefix":"","firstName":"Yang","middleName":"","lastName":"He","suffix":""}],"badges":[],"createdAt":"2026-02-06 12:23:44","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8806987/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8806987/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":103507006,"identity":"c05f2113-fbae-4e5d-8f5a-e08d7877075a","added_by":"auto","created_at":"2026-02-26 13:40:11","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1390720,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eProcedures for constructing the articular disc-condyle model and color map deviation analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eKey steps in constructing models and analyzing bone remodeling using multimodal image registration technology:\u003cbr\u003e\n \u003cstrong\u003e(A) Step 1:\u003c/strong\u003eReconstruction of the 3D articular disc model from MRI data\u003cbr\u003e\n \u003cstrong\u003e(B) Step 2:\u003c/strong\u003eReconstruction of the 3D condylar model from CT/CBCT data\u003cbr\u003e\n \u003cstrong\u003e(C) Step 3:\u003c/strong\u003ePrecise registration of the articular disc and condyle models to form the disc-condyle complex model\u003cbr\u003e\n \u003cstrong\u003e(D) Step 4:\u003c/strong\u003eDefining the sigmoid notch and coronoid process to align the 3D models, followed by color map deviation analysis of condylar models at different time points\u003c/p\u003e","description":"","filename":"Fig.1.png","url":"https://assets-eu.researchsquare.com/files/rs-8806987/v1/93b3e0a99e4854bb1f4b8855.png"},{"id":103380611,"identity":"43fb30cd-1e98-43d7-b54d-5e29070f98f8","added_by":"auto","created_at":"2026-02-25 05:37:21","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":997098,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eDivision of the proximal and distal bone segments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe condyle is divided into proximal segments (p) and proximal segments (d) based on the fracture site（A、B）or the bone union site（B、D）\u003c/p\u003e","description":"","filename":"Fig.2.png","url":"https://assets-eu.researchsquare.com/files/rs-8806987/v1/b03e10d7ae436b581c9a4707.png"},{"id":103380604,"identity":"7c0a0401-7fa9-4a98-afa7-91f7abbce3f2","added_by":"auto","created_at":"2026-02-25 05:37:21","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":915726,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMeasurement of condylar volume\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(A)\u003c/strong\u003e Identifying the lowest point of the sigmoid notch\u003cbr\u003e\n \u003cstrong\u003e(B)\u003c/strong\u003e Determining the plane tangent to the lowest point of the sigmoid notch; the volume of the red-colored portion was measured\u003c/p\u003e","description":"","filename":"Fig.3.png","url":"https://assets-eu.researchsquare.com/files/rs-8806987/v1/eb97c4192c274566145c2443.png"},{"id":103507288,"identity":"894cba67-8c00-4acf-bfa6-1960b3bea54e","added_by":"auto","created_at":"2026-02-26 13:40:54","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":2756764,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eDistribution patterns of bone formation and bone resorption (Superior View)\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(A-D) Distribution of bone formation:\u003c/strong\u003e (A) Bone formation distributed only in the distal segment; (B) Bone formation distributed only in the proximal segment; (C) Bone formation distributed in both proximal and distal segments; (D) No obvious bone formation\u003cbr\u003e\n \u003cstrong\u003e(E-H) Distribution of bone resorption:\u003c/strong\u003e (E) Bone resorption distributed only in the proximal segment; (F) Bone resorption distributed only in the distal segment; (G) Bone resorption distributed in both proximal and distal segments; (H) No obvious bone resorption. (\u003cstrong\u003ep\u003c/strong\u003e: proximal segment; \u003cstrong\u003ed\u003c/strong\u003e: distal segment)\u003c/p\u003e","description":"","filename":"Fig.4.png","url":"https://assets-eu.researchsquare.com/files/rs-8806987/v1/47f4357e4ee8d4d2d3e9c5b2.png"},{"id":103507055,"identity":"530d4098-8ca8-4317-99ce-7868498b69ac","added_by":"auto","created_at":"2026-02-26 13:40:18","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":1245786,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFour types of condylar remodeling\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e（red：bone formation，blue：bone resorption）\u003cstrong\u003e(A)\u003c/strong\u003eBone formation dominant \u003cstrong\u003e(B)\u003c/strong\u003e Bone resorption dominant \u003cstrong\u003e(C)\u003c/strong\u003e Balanced bone formation and resorption \u003cstrong\u003e(D)\u003c/strong\u003e No obvious remodeling\u003c/p\u003e","description":"","filename":"Fig.5.png","url":"https://assets-eu.researchsquare.com/files/rs-8806987/v1/3fc7360f1c818165c920600a.png"},{"id":103380610,"identity":"ec27628e-c561-4c13-bbbb-893412592325","added_by":"auto","created_at":"2026-02-25 05:37:21","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":928164,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eDisplacment of fracture fragment and TMJ disk\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(A)\u003c/strong\u003e Non-displaced condylar fracture fragment \u003cstrong\u003e(B)\u003c/strong\u003e Displaced condylar fracture fragment \u003cstrong\u003e(C)\u003c/strong\u003eNon-displaced articular disc \u003cstrong\u003e(D)\u003c/strong\u003e Displaced articular disc (\u003cstrong\u003e↓\u003c/strong\u003e: articular disc; \u003cstrong\u003ep\u003c/strong\u003e: proximal segment; \u003cstrong\u003ed\u003c/strong\u003e: distal segment)\u003c/p\u003e","description":"","filename":"Fig.6.png","url":"https://assets-eu.researchsquare.com/files/rs-8806987/v1/c5f59cd05ccb3ca0e9a5c9ac.png"},{"id":103380613,"identity":"86d9acb4-8a5e-4e7f-a98d-19d0ad3321de","added_by":"auto","created_at":"2026-02-25 05:37:21","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":617510,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eDetermination of disc-covered area\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(A)\u003c/strong\u003e Color map analysis performed after aligning the post-treatment 3D disc-condyle model with the pre-treatment 3D condylar model\u003cbr\u003e\n \u003cstrong\u003e(B)\u003c/strong\u003e Projection of the articular disc onto the condylar surface to form the disc-covered condylar area\u003c/p\u003e","description":"","filename":"Fig.7.png","url":"https://assets-eu.researchsquare.com/files/rs-8806987/v1/19f92991464e121eb997fc51.png"},{"id":103507126,"identity":"efd30d80-21dc-4b2e-80b2-1ea2ba9c8963","added_by":"auto","created_at":"2026-02-26 13:40:31","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":333060,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eChanging trends in the distribution of bone formation/resorption in the proximal and distal segments\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Fig.8.png","url":"https://assets-eu.researchsquare.com/files/rs-8806987/v1/7fb4e94e49d19e54fb7eae90.png"},{"id":103380606,"identity":"774552e3-3a54-45d0-90ed-bac771f1056d","added_by":"auto","created_at":"2026-02-25 05:37:21","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":980822,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCondylar remodeling at different post-treatment time points\u003c/strong\u003e\u003cbr\u003e\n \u003cstrong\u003e(A)\u003c/strong\u003e at 3 months post-treatment \u003cstrong\u003e(B)\u003c/strong\u003e at 6 months post-treatment \u003cstrong\u003e(C)\u003c/strong\u003eat 1 year post-treatment (\u003cstrong\u003ep\u003c/strong\u003e: proximal segment; \u003cstrong\u003ed\u003c/strong\u003e: distal segment)\u003c/p\u003e","description":"","filename":"Fig.9.png","url":"https://assets-eu.researchsquare.com/files/rs-8806987/v1/9a6fa202257bd4823fa430dc.png"},{"id":103380609,"identity":"8521cb6f-8736-4303-bdd0-b545435e80f7","added_by":"auto","created_at":"2026-02-25 05:37:21","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":923654,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCondyle-disc position relationship before and after conservative treatment\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e(A) Pre-treatment: The condylar fracture fragment is displaced\u003cbr\u003e\n (B) 6 months post-treatment: The condyle has returned to the glenoid fossa\u003cbr\u003e\n (C) Pre-treatment: The articular disc is displaced\u003cbr\u003e\n (D) 6 months post-treatment: The articular disc has returned to the glenoid fossa\u003cbr\u003e\n (↓: articular disc; d: fracture fragment; c: condyle)\u003c/p\u003e","description":"","filename":"Fig.10.png","url":"https://assets-eu.researchsquare.com/files/rs-8806987/v1/988d1e84a7c77c792929a19e.png"},{"id":103380612,"identity":"0f11b2d1-16ed-412b-bec3-574ecd29bce5","added_by":"auto","created_at":"2026-02-25 05:37:21","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":1639949,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eDifferences in condylar remodeling between disc-covered and non-disc-covered regions\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Fig.11.png","url":"https://assets-eu.researchsquare.com/files/rs-8806987/v1/2f081c9e9a162cf39131ace6.png"},{"id":103510079,"identity":"27e54568-9ca5-4c04-8f2d-c3cedbc5f874","added_by":"auto","created_at":"2026-02-26 14:03:49","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":13585330,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8806987/v1/2ac9b374-b336-461d-a4b4-784edb488f21.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Three-dimensional Spatiotemporal Analysis of Condylar Remodeling After Conservative Treatment of Pediatric Mandibular Condylar Sagittal Fractures","fulltext":[{"header":"Sources of support","content":"\u003cp\u003eThis study was supported by the National Key Research and Development Program of China (Grant No. 2023YFC3011901), Capital\u0026rsquo;s Funds for Health Improvement and Research (Grant No. 2022-4-4109), and the Beijing Natural Science Foundation (Grant Nos. L242136 and L252201).\u003c/p\u003e"},{"header":"1. Introduction","content":"\u003cp\u003eMandibular fractures represent the most common type of maxillofacial fracture in children [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e], with the condyle being the most frequently affected site, accounting for approximately 25%\u0026ndash;80% of all mandibular fractures [\u003cspan additionalcitationids=\"CR2 CR3 CR4\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. In growing children, the condyle functions as a primary growth center of the mandible, and inappropriate management may result in malocclusion, TMJ dysfunction, mandibular developmental disturbances, and even ankylosis. Previous studies have demonstrated that children younger than 12 years exhibit a strong capacity for condylar bone remodeling and growth [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Conservative treatment strategies, including early functional exercises, occlusal splints, soft diets, and orthodontic interventions [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], have been shown to effectively restore condylar height and normal TMJ function [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Owing to the potential risks associated with surgical intervention, such as secondary condylar injury, nerve damage, and scarring, conservative treatment remains the preferred therapeutic approach among most clinicians [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAs a critical component of the TMJ, the morphology of the mandibular condyle is closely associated with joint stability and function. Previous evaluations of condylar remodeling have largely relied on clinical findings and two-dimensional (2D) imaging, which lack longitudinal and dynamic observations [\u003cspan additionalcitationids=\"CR12\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Advances in three-dimensional reconstruction and image registration technologies have enabled more intuitive visualization of condylar remodeling and facilitated the investigation of its spatial changes.\u003c/p\u003e \u003cp\u003ePrevious research on factors influencing condylar remodeling has primarily focused on fracture patterns and the degree of displacement. In recent years, with the widespread application of magnetic resonance imaging (MRI), increasing attention has been directed toward soft tissue injuries, particularly anterior disc displacement. Animal studies have demonstrated that the articular disc participates in condylar regeneration and mandibular growth [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Liu et al. [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e] reported that anterior disc displacement and unfavorable condylar remodeling occurred following SFMC in children, suggesting that persistent anterior disc displacement may be associated with increased condylar width and depth and reduced condylar height. These findings indicate a potential influence of the TMJ disc on condylar remodeling. However, clinical assessment of disc displacement relies on MRI, whereas evaluation of condylar remodeling is typically based on CT imaging. The application of multimodal image registration techniques to fuse CT and MRI images allows direct visualization of the spatial relationship between the articular disc and the condyle.\u003c/p\u003e \u003cp\u003eSagittal fractures are characterized by a fracture line that traverses the articular surface and extends obliquely toward the medial aspect of the condylar head or neck, accounting for approximately 9%\u0026ndash;29% of all condylar fractures [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. In pediatric patients, sagittal fractures are predominantly managed conservatively. Under the traction of the lateral pterygoid muscle, the articular disc typically displaces anteromedially and inferiorly together with the medial condylar fragment. Consequently, this characteristic displacement pattern provides a \u0026ldquo;natural model\u0026rdquo; for investigating the dynamic relationship between condylar remodeling and the articular disc [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe aim of this study was to apply multimodal image registration techniques to systematically analyze condylar remodeling patterns in pediatric SFMC following conservative treatment and to investigate the influence of articular disc position on this process.\u003c/p\u003e"},{"header":"2. Materials and Methods","content":"\u003cdiv id=\"Sec3\"\u003e\n \u003ch2\u003e2.1 Patients\u003c/h2\u003e\n \u003cp\u003eFrom September 2014 to January 2025, 28 patients (19 males and 9 females; 15 bilateral fractures and 13 unilateral fractures; age range, 4\u0026ndash;12 years) with a total of 43 SFMCs were enrolled. The inclusion criteria were as follows: (1) age\u0026thinsp;\u0026le;\u0026thinsp;12 years; (2) initial presentation within 2 weeks after injury; (3) confirmed diagnosis of sagittal condylar fracture; (4) treatment with conservative management; and (5) availability of TMJ MRI and spiral CT or cone-beam computed tomography (CBCT) data obtained before treatment and at 3 months, 6 months, or 1 year after treatment. The exclusion criteria included: (1) developmental anomalies or inflammatory diseases (e.g., idiopathic arthritis); (2) dislocation of the ramus stump into the glenoid fossa; and (3) concomitant facial fractures.\u003c/p\u003e\n \u003cp\u003eAll patients were treated conservatively. They were instructed to wear occlusal splints and to perform mouth-opening, lateral excursion, and protrusive functional exercises under physician supervision for a minimum of 3 months [2]. Follow-up examinations were conducted at 3 months, 6 months, and 1 year after treatment. Spiral CT or CBCT scans were obtained at all follow-up time points, while MRI examinations were additionally performed at the 6-month and 1-year evaluations.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec4\"\u003e\n \u003ch2\u003e2.2 Image Acquisition\u003c/h2\u003e\n \u003cp\u003eSpiral computed tomography (CT) examinations (tube voltage, 76\u0026ndash;80 kV; tube current, 4.2\u0026ndash;6.0 mA; field of view [FOV], 6 \u0026times; 6 cm) were performed with patients in the intercuspal position (ICP). The slice thickness was 0.48 mm. CBCT examinations (3D Accuitomo, J. Morita Mfg. Corp., Japan; 90 kV; 5 mA; FOV, 4 \u0026times; 4 cm or 6 \u0026times; 6 cm; voxel size, 0.25 \u0026times; 0.25 \u0026times; 0.25 mm) were also conducted in the intercuspal position. Temporomandibular joint (TMJ) MRI examinations (GE 1.5 T, USA; dual coil) were performed using proton density (PD)-weighted sequences (TR, 3000 ms; TE, 12 ms), with oblique sagittal localizers oriented perpendicular to the long axis of the condyle. The slice thickness was 2.5 mm.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec5\"\u003e\n \u003ch2\u003e2.3 Multimodal Image Registration\u003c/h2\u003e\n \u003cp\u003eReconstruction of three-dimensional (3D) models of the condyle and articular disc: Original Digital Imaging and Communications in Medicine (DICOM) files from spiral CT/CBCT and MRI were imported into Mimics Medical 21.0 software. Three-dimensional models of the condyle and articular disc were reconstructed using threshold-based segmentation followed by manual correction (Fig.\u0026nbsp;1A, B).\u003c/p\u003e\n \u003cp\u003eColor map deviation analysis of 3D condylar models: All 3D condylar models were exported in STL format and imported into Geomagic Studio 2014 software. The coronoid process and sigmoid notch regions were designated as reference regions using the \u0026ldquo;Select\u0026rdquo; tool. Based on these reference regions, the \u0026ldquo;Best Fit Alignment\u0026rdquo; function was applied to accurately superimpose the condylar models. Color map deviation analysis was then performed between adjacent time points (Fig.\u0026nbsp;1C).\u003c/p\u003e\n \u003cp\u003eReconstruction of fused 3D condyle\u0026ndash;disc models using multimodal image registration: Three-dimensional condylar models (STL format) were imported into the Mimics project files containing the 3D articular disc models. At least three MRI slices displaying clear articular disc and condylar structures were selected, and the 3D condylar model was aligned with the corresponding condylar contours on these slices until optimal matching was achieved (Fig. 1D).\u003c/p\u003e\n \u003cp\u003eKey steps in constructing models and analyzing bone remodeling using multimodal image registration technology:\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(A) Step 1\u003c/strong\u003e: Reconstruction of the 3D articular disc model from MRI data\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(B) Step 2\u003c/strong\u003e: Reconstruction of the 3D condylar model from CT/CBCT data\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(C) Step 3\u003c/strong\u003e: Precise registration of the articular disc and condyle models to form the disc-condyle complex model\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(D) Step 4\u003c/strong\u003e: Defining the sigmoid notch and coronoid process to align the 3D models, followed by color map deviation analysis of condylar models at different time points\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec6\"\u003e\n \u003ch2\u003e2.4 Evaluation of 3D Condyle Models\u003c/h2\u003e\n \u003cp\u003eCondylar remodeling was evaluated across three phases: Phase P1 (pre-treatment to 3 months), Phase P2 (3 to 6 months), and Phase P3 (6 months to 1 year). According to the location of the fracture line, the condyle was divided into a proximal segment (ramus stump) and a distal segment (condylar fragment) (Fig. 2).\u003c/p\u003e\n \u003cdiv id=\"Sec7\"\u003e\n \u003ch2\u003e2.4.1 Evaluation of Condylar Remodeling\u003c/h2\u003e\n \u003cp\u003eCondylar volume was quantified by defining a reference plane tangent to the lowest point of the sigmoid notch using Mimics Research 21.0, and the volume above this plane was calculated (Fig.\u0026nbsp;3). Three-dimensional condylar models from consecutive time points were registered, and root mean square (RMS) deviation values were calculated.\u003c/p\u003e\n \u003cp\u003eThe spatial distribution of bone resorption and bone formation was classified into four categories: involvement of the proximal segment only, involvement of the distal segment only, involvement of both proximal and distal segments, and no obvious bone resorption or formation (Fig. 4). The number of cases in each category was recorded at 3 months, 6 months, and 1 year after treatment.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec8\"\u003e\n \u003ch2\u003e2.4.2 Evaluation of Proximal and Distal Segment Remodeling\u003c/h2\u003e\n \u003cp\u003eThe volumes of the proximal and distal segments were measured separately to assess remodeling activity. Remodeling patterns were classified into four types: bone formation dominant, bone resorption dominant, balanced bone formation and resorption, and no obvious remodeling (Fig. 5). The number of cases corresponding to each pattern was recorded.\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec9\"\u003e\n \u003ch2\u003e2.5 Evaluation of 3D Condyle\u0026ndash;Disc Models\u003c/h2\u003e\n \u003cp\u003eDisplacement of the fracture fragment and articular disc was evaluated before and after treatment [16]. When the majority of the condylar fracture fragment or articular disc was located within the glenoid fossa, it was defined as non-displaced; when the majority was located outside the glenoid fossa, it was defined as displaced (Fig.\u0026nbsp;6).\u003c/p\u003e\n \u003cp\u003eThe articular disc was projected onto the condylar surface in a superior view to delineate disc-covered and non-disc-covered areas (Fig. 7). Following registration of pre- and post-treatment models, surface deviation was assessed using color mapping, and RMS deviation values were calculated separately for each area.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec10\"\u003e\n \u003ch2\u003e2.6 Statistical Methods\u003c/h2\u003e\n \u003cp\u003eStatistical analyses were conducted using SPSS software (version 26.0). Paired-samples t-tests were used to evaluate changes in volume and RMS deviation of the affected condyle and to compare specific subregions (proximal versus distal segments and disc-covered versus non-disc-covered areas). For the contralateral condyle, independent-samples t-tests or Mann\u0026ndash;Whitney U tests were applied depending on data distribution. Categorical variables were analyzed using Fisher\u0026rsquo;s exact test. Statistical significance was defined as a P value\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"3. Results","content":"\u003cp\u003eThe study cohort included 28 children (19 males and 9 females; mean age, 8.29\u0026thinsp;\u0026plusmn;\u0026thinsp;2.19 years) with 15 bilateral and 13 unilateral condylar fractures. Clinically, fracture healing proceeded uneventfully, and no significant complications were observed during the follow-up period.\u003c/p\u003e\n\u003cp\u003eBased on the availability of serial imaging data, cases were grouped into three intervals: pre-treatment to 3 months (8 patients, 13 joints), 3 to 6 months (6 patients, 10 joints), and 6 months to 1 year (11 patients, 18 joints). Paired MRI data were available for 9 patients (15 joints). In total, 76 three-dimensional condylar models were reconstructed across all follow-up time points (3 months, n\u0026thinsp;=\u0026thinsp;20; 6 months, n\u0026thinsp;=\u0026thinsp;29; 1 year, n\u0026thinsp;=\u0026thinsp;27), together with 15 fused condyle\u0026ndash;disc models. The registration process demonstrated high accuracy, with a RMS error of 0.42 mm.\u003c/p\u003e\n\u003cdiv id=\"Sec12\"\u003e\n \u003ch2\u003e3.1 Results of 3D Condyle Models\u003c/h2\u003e\n \u003cdiv id=\"Sec13\"\u003e\n \u003ch2\u003e3.1.1 Condylar Remodeling\u003c/h2\u003e\n \u003cp\u003eAs summarized in Table\u0026nbsp;1, the volume of the fractured condyle showed a significant reduction during Phase P1 (P\u0026thinsp;=\u0026thinsp;0.006) and a significant increase during Phase P3 (P\u0026thinsp;=\u0026thinsp;0.005), whereas no statistically significant change was observed during Phase P2 (P\u0026thinsp;=\u0026thinsp;0.977). These results indicate that condylar remodeling was characterized predominantly by bone resorption within the first 3 months after treatment, followed by a shift toward bone formation after 6 months. In contrast, the contralateral condyle remained volumetrically stable throughout the study period, with no significant differences observed across the three phases (P1, P\u0026thinsp;=\u0026thinsp;0.183; P2, P\u0026thinsp;=\u0026thinsp;0.173; P3, P\u0026thinsp;=\u0026thinsp;0.833).\u003c/p\u003e\n \u003cp\u003eSequential surface deviation analysis revealed a gradual decline in remodeling activity over time. The RMS deviation in Phase P1 was significantly higher than that in Phase P2 (P\u0026thinsp;=\u0026thinsp;0.024), which was in turn significantly higher than that in Phase P3 (P\u0026thinsp;=\u0026thinsp;0.020). These findings indicate that condylar remodeling activity was most pronounced in the early post-treatment period and progressively diminished thereafter.\u003c/p\u003e\n \u003cdiv\u003e\n \u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 1\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003e\u003cstrong\u003eChanges in Volume and RMS of the Affected Condyle at Different Post-Treatment Intervals(* P\u0026lt;0.05; ** P\u0026lt;0.001)\u003c/strong\u003e As detailed in Tables 2 and 3, no statistically significant differences were observed in the overall distribution of bone formation and resorption on the fractured condyle over time (P\u0026thinsp;=\u0026thinsp;0.059; P\u0026thinsp;=\u0026thinsp;0.063). Bone resorption was predominantly observed in the proximal segment, with the proportion of affected cases decreasing during the first 6 months. In contrast, bone formation occurred mainly in the distal segment and demonstrated an increasing trend over the same period (Fig. 8).\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePhase\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eTime piont\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003en\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eCondylar volume(mm\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eP-value\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eRMS\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eP-value\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003eP1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePre-treatment\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" rowspan=\"2\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1612.77\u0026thinsp;\u0026plusmn;\u0026thinsp;74.52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.006\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e*\u003c/strong\u003e\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3 months\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1380.95\u0026thinsp;\u0026plusmn;\u0026thinsp;83.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003eP2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3 months\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" rowspan=\"2\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1184.43\u0026thinsp;\u0026plusmn;\u0026thinsp;71.81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003e0.977\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.3628\u0026thinsp;\u0026plusmn;\u0026thinsp;0.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.024\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e*\u003c/strong\u003e\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6 months\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1186.61\u0026thinsp;\u0026plusmn;\u0026thinsp;99.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.9773\u0026thinsp;\u0026plusmn;\u0026thinsp;0.45\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003eP3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6 months\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" rowspan=\"2\"\u003e\n \u003cp\u003e18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1540.84\u0026thinsp;\u0026plusmn;\u0026thinsp;98.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.005\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e*\u003c/strong\u003e\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.6438\u0026thinsp;\u0026plusmn;\u0026thinsp;0.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.020\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e*\u003c/strong\u003e\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1 year\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1705.24\u0026thinsp;\u0026plusmn;\u0026thinsp;111.54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.1967\u0026thinsp;\u0026plusmn;\u0026thinsp;0.32\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cdiv\u003e\n \u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 2\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003eSpatial Distribution of Bone Formation at Different Post-Treatment Time Points\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eTime piont\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003edistal segment only\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eproximal segment only\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eboth proximal and distal segments\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eno obvious formation\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eP-value\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e3 months(n\u0026thinsp;=\u0026thinsp;20)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12(60%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1(5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3(15%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4(20%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"3\"\u003e\n \u003cp\u003e0.059\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"1\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e6 months(n\u0026thinsp;=\u0026thinsp;29)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14(48.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14(48.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1(3.4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"1\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e1 year(n\u0026thinsp;=\u0026thinsp;27)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12(44.4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2(7.4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10(37%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3(11.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"1\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cdiv\u003e\n \u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 3\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003eSpatial Distribution of Bone Resorption at Different Post-Treatment Time Points\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colspan=\"6\"\u003e\n \u003cp\u003ebone resorption\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eTime piont\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003edistal segment only\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eproximal segment only\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eboth proximal and distal segments\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eno obvious resorption\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eP-value\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e3 months(n\u0026thinsp;=\u0026thinsp;20)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1(5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9(45%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3(15%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7(35%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"3\"\u003e\n \u003cp\u003e0.063\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"1\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e6 months(n\u0026thinsp;=\u0026thinsp;29)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14(48.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1(3.4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14(48.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"1\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e1 year(n\u0026thinsp;=\u0026thinsp;27)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1(3.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6(22.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1(3.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e19(70.4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"1\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec14\"\u003e\n \u003ch2\u003e3.1.2 Proximal and Distal Segment Remodeling\u003c/h2\u003e\n \u003cp\u003eAs shown in Table\u0026nbsp;4, during Phase P1, the volume of the proximal segment decreased significantly (P\u0026thinsp;\u0026lt;\u0026thinsp;0.000), whereas the volume of the distal segment increased significantly (P\u0026thinsp;=\u0026thinsp;0.014). Quantitatively, the reduction in proximal segment volume (390.83\u0026thinsp;\u0026plusmn;\u0026thinsp;44.87 mm\u0026sup3;) was significantly greater than the increase in distal segment volume (203.48\u0026thinsp;\u0026plusmn;\u0026thinsp;41.39 mm\u0026sup3;) (P\u0026thinsp;=\u0026thinsp;0.007). As detailed in Table\u0026nbsp;5 and Fig.\u0026nbsp;9, the proximal and distal segments exhibited significantly different remodeling patterns (P\u0026thinsp;\u0026lt;\u0026thinsp;0.000). These results indicate that, during the early post-treatment phase, bone resorption, which predominated in the proximal segment, exceeded bone formation, which predominated in the distal segment. Separate volumetric analyses of the proximal and distal segments at 6 months and 1 year were not feasible because fracture healing rendered the fracture line indistinguishable for three-dimensional segmentation.\u003c/p\u003e\n \u003cdiv\u003e\n \u003ctable id=\"Tab4\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 4\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003eVolumetric Changes in Proximal and Distal Segments at 3 Months Post-Treatment\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003en\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eProximal segment volume(mm\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eP-value\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eDistal segment volume(mm\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eP-value\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003ePre-treatment\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e886.01\u0026thinsp;\u0026plusmn;\u0026thinsp;59.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003e0.000\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e726.76\u0026thinsp;\u0026plusmn;\u0026thinsp;49.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003e0.014\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e3 months\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e495.18\u0026thinsp;\u0026plusmn;\u0026thinsp;55.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e885.77\u0026thinsp;\u0026plusmn;\u0026thinsp;43.89\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cdiv\u003e\n \u003ctable id=\"Tab5\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 5\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003eComparison of Remodeling Pattern Types of the Distal and Proximal Segments Post-Treatment\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"6\"\u003e\n \u003cp\u003eremodeling patterns\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ebone formation dominant\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ebone resorption dominant\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBalanced bone formation and resorption\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eno obvious remodeling\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eP-value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003edistal segment(n\u0026thinsp;=\u0026thinsp;76)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e62(81.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4(5.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4(5.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6(9.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003e0.000\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003eproximal segment(n\u0026thinsp;=\u0026thinsp;76)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e27(35.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30(39.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3(3.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16(21.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec15\"\u003e\n \u003ch2\u003e3.2 Results of 3D Condyle\u0026ndash;Disc Models\u003c/h2\u003e\n \u003cp\u003eFollowing fracture, anterior displacement was observed in 60% (26/43) of the fracture fragments (distal segments) and in 100% (15/15) of the articular discs. After conservative treatment, all fracture fragments and articular discs returned to the glenoid fossa (Fig.\u0026nbsp;10).\u003c/p\u003e\n \u003cp\u003eAmong the 15 reconstructed condyle\u0026ndash;disc models, significant bone formation was observed in 93.3% (14/15) of cases. The articular disc was predominantly positioned over the surface of the distal segment (Fig. 11). As shown in Table 6, the RMS deviation values in disc-covered areas differed significantly from those in non-disc-covered areas (P\u0026thinsp;=\u0026thinsp;0.012). These findings suggest that articular disc coverage may be critical for promoting bone formation.\u003c/p\u003e\n \u003cp\u003eSignificant bone formation is observed in the disc-covered area after conservative treatment, while the non-disc-covered area is dominated by bone resorption\u003c/p\u003e\n \u003cdiv\u003e\n \u003ctable id=\"Tab6\" border=\"1\" class=\"fr-table-selection-hover\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 6\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003eRMS Differences Between Disc-Covered and Non-Disc-Covered Regions\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003en\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eRMS\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eP-value\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003edisc-covered area\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.8670\u0026thinsp;\u0026plusmn;\u0026thinsp;0.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003e0.012\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003enon-disc-covered area\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.3911\u0026thinsp;\u0026plusmn;\u0026thinsp;0.54\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n\u003c/div\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eBy integrating three-dimensional reconstruction, multimodal image registration, and color map deviation analysis, this study characterized the remodeling process of pediatric sagittal condylar fractures treated conservatively. The results demonstrated dynamic changes in condylar volume and morphology. Moreover, a significant association was identified between the articular disc and remodeling outcomes, with bone formation predominantly occurring in disc-covered regions, suggesting that the articular disc plays a crucial role in condylar remodeling.\u003c/p\u003e \u003cp\u003eThis study confirms that condylar healing in pediatric patients involves an active and complex remodeling process rather than simple osseous union of the fracture line, which is consistent with previous reports [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Condylar remodeling was most pronounced within the first 3 months after fracture and was characterized by a biphasic pattern of volume change, with an initial reduction followed by expansion. This pattern reflects the physiological sequence of fracture healing, in which osteoclastic resorption precedes osteoblastic bone formation. Despite this regenerative capacity, the mean condylar volume at 1 year remained lower than pre-injury levels. This finding suggests that although substantial adaptive remodeling occurs, complete restoration of pre-injury volume is difficult to achieve, in agreement with Li et al. [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], although longer-term follow-up is required to confirm this trend. Notably, the discrepancy between condylar morphology and joint function observed in the present cohort is consistent with the findings of Zhu et al. [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], who reported satisfactory TMJ function despite varied healing morphologies.\u003c/p\u003e \u003cp\u003eDistinct remodeling patterns were identified between the proximal and distal segments. In sagittal fractures, the distal fragment is displaced anteromedially and inferiorly, creating a \u0026ldquo;bony step\u0026rdquo; relative to the vertically taller proximal ramus stump. The remodeling process therefore functions to recontour this irregularity and restore articular congruity. This mechanism is consistent with the observations of Li et al. [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e], who reported that the ramus stump undergoes substantial resorption until its height approximates that of the fracture fragment. Temporally, proximal resorption was most pronounced during Phase P1. During Phase P2, a dynamic equilibrium was observed, in which proximal resorption was offset by distal bone formation, resulting in a stable overall condylar volume. After 6 months, bone formation in the distal segment became the dominant process, leading to a net increase in condylar volume. These findings suggest a gradual attenuation of proximal resorption accompanied by sustained long-term bone formation in the distal segment.\u003c/p\u003e \u003cp\u003eThe observed remodeling pattern appears to be strongly influenced by repositioning of the articular disc. The finding that the displaced disc returned to the glenoid fossa within 3\u0026ndash;6 months is consistent with the results reported by Liu et al. [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. It is hypothesized that the initial absence of disc coverage over the proximal segment exposes this region to excessive mechanical loading, thereby inducing bone resorption. Conversely, disc repositioning may restore a physiological biomechanical environment conducive to osteogenesis. Animal studies have demonstrated that the articular disc regulates condylar regeneration and mandibular growth in rats [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Disc-mediated alterations in stress distribution on the condylar surface may therefore represent a potential mechanism underlying the predominance of bone formation in disc-covered areas and bone resorption in non-disc-covered areas, although this hypothesis requires further validation through animal experiments. With respect to bone resorption, Li et al. [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] analyzed two-dimensional images from 93 patients younger than 12 years with intracapsular condylar fractures and reported that abduction of the mandibular ramus was a major contributor to condylar resorption and height reduction, particularly in complex fractures. This factor was not addressed in the present study. Consequently, future investigations should explore whether therapeutic strategies focusing solely on disc repositioning are sufficient for the management of pediatric condylar fractures.\u003c/p\u003e \u003cp\u003eIdeally, fracture healing progresses from an early resorptive phase to a later regenerative phase. Specifically, degenerative changes in the mandibular ramus stump predominate initially, followed by regenerative remodeling. This biphasic pattern is consistent with the findings of Liu et al. [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e], who reported that condylar height decreases during the first 6 months after pediatric sagittal fractures but subsequently exhibits a growth rate exceeding that of the unaffected side. Clinically, the early resorptive phase and the associated reduction in condylar height often result in transient exacerbation of mandibular deviation toward the affected side during Phase P2. As bone formation accelerates in the distal segment, this deviation is gradually corrected. Whether such compensatory growth ultimately restores complete symmetry remains to be determined through long-term follow-up studies.\u003c/p\u003e \u003cp\u003eThis study represents a novel application of multimodal MRI\u0026ndash;CT/CBCT registration to visualize three-dimensional condylar remodeling and its spatial relationship with the articular disc in pediatric sagittal fractures. Nevertheless, several limitations should be acknowledged. First, inherent registration errors are unavoidable. Because the pediatric mandible is undergoing active growth, it is difficult to completely distinguish remodeling changes from physiological growth. Future studies should focus on optimizing registration algorithms to minimize this confounding effect. Second, the sample size of the present study was limited, and characterization of condylar remodeling patterns would benefit from validation in larger cohorts. Finally, long-term condylar development was not assessed, and the potential influence of articular disc displacement on long-term outcomes warrants further investigation.\u003c/p\u003e \u003cp\u003eIn conclusion, this study demonstrates that conservative treatment of sagittal condylar fractures in children younger than 12 years is associated with significant volumetric and morphological remodeling within the first year after injury. Remodeling activity is most pronounced during the initial 3 months and exhibits a distinct spatial pattern, with bone formation predominating in the distal segment and bone resorption occurring primarily in the proximal segment. Furthermore, condylar remodeling is closely associated with the position of the articular disc.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eThe following additional information is required for submission. Please note that failure to respond to these questions/statements will mean your submission will be returned to you. If you have nothing to declare in any of these categories then this should be stated.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePlease state any conflict of interests.\u003c/strong\u003e A conflict of interest exists when an author or the author's institution has financial or personal relationships with other people or organisations that inappropriately influence (bias) his or her actions. Financial relationships are easily identifiable, but conflicts can also occur because of personal relationships, academic competition, or intellectual passion. A conflict can be actual or potential, and full disclosure to The Editor is the safest course.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNone\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003ePlease state any sources of funding for your research\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eThis study was supported by National Key Research and Development Program of China (grant No. 2023YFC3011901), Capital’s Funds for Health Improvement and Research (grant No. 2022-4-4109), Beijing Natural Science Foundation\u003c/p\u003e\n \u003cp\u003e(grant No. L242136) and Beijing Natural Science Foundation\u003c/p\u003e\n \u003cp\u003e(grant No. L252201)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eDOES YOUR STUDY INVOLVE HUMAN OR ANIMALSUBJECTS? Please cross out whichever is not applicable\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eYes.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eIf your study involves human or animal subjects or records of human patients you MUST have obtained ethical approval. \u0026nbsp; Ethics approval or exemption are required for retrospective studies on patients' records\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePlease state whether Ethical Approval was given, by whom and the relevant Judgement’s reference number\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eThis study was approved by the Biomedical Ethics Review Committee of Peking University School and Hospital of Stomatology (Approval No.\u0026nbsp;PKUSSIRB-2025111113).\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003ePatient Consent – please state that written patient consent has been obtained to publish clinical photographs. \u0026nbsp;If you have no clinical photographs, please state \"not required”. \u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eThe Journal may request a copy of this consent prior to acceptance\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNot required.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003ePlease add a statement to confirm that all authors have viewed and agreed to the submission\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eAll authors have viewed and agreed to the submission.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eThis information must also be inserted into your manuscript under the acknowledgements section prior to the References.\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e\u003cbr\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eCooney M, O'connell JE, Vesey JA, Van Eeden S (2020) Non-surgical management of paediatric and adolescent mandibular condyles: A retrospective review of 49 consecutive cases treated at a tertiary referral centre[J]. J Craniomaxillofac Surg 48(7):666\u0026ndash;671\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhao YM, Yang J, Bai RC, Ge LH, Zhang Y (2014) A retrospective study of using removable occlusal splint in the treatment of condylar fracture in children[J]. J Craniomaxillofac Surg 42(7):1078\u0026ndash;1082\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShi J, Chen Z, Xu B (2014) Causes and treatment of mandibular and condylar fractures in children and adolescents: a review of 104 cases[J]. JAMA Otolaryngol Head Neck Surg 140(3):203\u0026ndash;207\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDu C, Xu B, Zhu Y, Zhu M (2021) Radiographic evaluation in three dimensions of condylar fractures with closed treatment in children and adolescents[J]. J Craniomaxillofac Surg 49(9):830\u0026ndash;836\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSteed MB, Schadel CM (2017) Management of Pediatric and Adolescent Condylar Fractures[J]. Atlas Oral Maxillofac Surg Clin North Am 25(1):75\u0026ndash;83\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStaderini E, Patini R, Tepedino M, Gasparini G, Zimbalatti MA, Marradi F, Gallenzi P (2020) Radiographic Assessment of Pediatric Condylar Fractures after Conservative Treatment with Functional Appliances-A Systematic Review[J]. Int J Environ Res Public Health, 17(24)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVesnaver A (2020) Dislocated pediatric condyle fractures - should conservative treatment always be the rule?[J]. J Craniomaxillofac Surg 48(10):933\u0026ndash;941\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMalinge M, Grimaud F, Perrin JP, Loin J, Anquetil M, Mercier J, Corre P, Bertin H (2022) Outcomes of functional treatment of condylar mandibular fractures with an articular impact: a retrospective study of 108 children[J]. J Stomatol Oral Maxillofac Surg 123(2):177\u0026ndash;183\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYesantharao PS, Lopez J, Reategui A, Jenny H, Najjar O, Yu JW, Yang R, Manson PN, Dorafshar A, Redett RJ (2021) Combined Symphyseal and Condylar Fractures: Considerations for Treatment in Growing Pediatric Patients[J]. Plast Reconstr Surg 148(1):51e\u0026ndash;62e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhu YF, Zou Y, Wang SZ, Du C X, Xu B, Zhu M (2020) Three-dimensional evaluation of condylar morphology after closed treatment of unilateral intracapsular condylar fracture in children and adolescents[J]. J Craniomaxillofac Surg 48(3):286\u0026ndash;292\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChang S, Yang Y, Liu Y, Wang J, Zhang W, Ma Q (2018) How Does the Remodeling Capacity of Children Affect the Morphologic Changes of Fractured Mandibular Condylar Processes After Conservative Treatment?[J]. J Oral Maxillofac Surg, 76(6): 1279.e1-1279.e7\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBruckmoser E, Undt G (2012) Management and outcome of condylar fractures in children and adolescents: a review of the literature[J]. Oral Surg Oral Med Oral Pathol Oral Radiol 114(5 Suppl):S86\u0026ndash;s106\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhou HH, Lv K, Yang RT, Li Z, Yang XW, Li ZB (2019) Mandibular condylar fractures in children and adolescents: 5-Year retrospective cohort study[J]. Int J Pediatr Otorhinolaryngol 119:113\u0026ndash;117\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi Z, Zhang W, Li ZB (2010) The role of the disc in the healing of displaced subcondylar fracture in the growing period: an experimental study in rats[J]. Int J Oral Maxillofac Surg 39(4):388\u0026ndash;393\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi Z, Li ZB (2012) Mandibular condylar growth in growing rats after experimentally displaced condylar fracture with associated attachment damage and disc displacement: an observation by polychrome sequential labeling[J]. J Oral Maxillofac Surg 70(4):896\u0026ndash;901\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu M, Zhao Y, He Y, An J, Lei J, Zhang Y (2020) Outcomes of anterior disc displacement and condylar remodelling for sagittal fracture of the mandibular condyle in children after closed treatment[J]. Int J Oral Maxillofac Surg 49(1):82\u0026ndash;89\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhou HH, Lv K, Yang RT, Li Z, Yang XW, Li ZB (2019) Abduction of the condyle head leads to condylar resorption: A radiologic study in children with intracapsular fractures[J]. Int J Pediatr Otorhinolaryngol 123:168\u0026ndash;174\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi Z, Zhang W, Li ZB, Li JR (2010) Mechanism in favorable prognosis of pediatric condylar fractures managed by closed procedures: an experimental study in growing rats[J]. Dent Traumatol 26(3):228\u0026ndash;235\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"clinical-oral-investigations","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"cloi","sideBox":"Learn more about [Clinical Oral Investigations](http://link.springer.com/journal/784)","snPcode":"784","submissionUrl":"https://submission.nature.com/new-submission/784/3","title":"Clinical Oral Investigations","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Children, Mandibular condyle, Sagittal fracture, Condylar remodeling, Articular disc","lastPublishedDoi":"10.21203/rs.3.rs-8806987/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8806987/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eObjective\u003c/h2\u003e \u003cp\u003eThis study investigated condylar remodeling and the role of the temporomandibular joint (TMJ) disc in growing patients with sagittal fractures of the mandibular condyle (SFMC) treated conservatively.\u003c/p\u003e\u003ch2\u003eMaterials and methods\u003c/h2\u003e \u003cp\u003eA retrospective analysis was performed on 28 children (aged 4\u0026ndash;12 years) with 43 SFMCs using three-dimensional models reconstructed from computed tomography (CT) and magnetic resonance imaging (MRI) obtained before treatment and at 3, 6, and 12 months after treatment. To evaluate condylar remodeling and its relationship with the articular disc, multimodal image registration was applied to fuse CT and MRI datasets.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThe results demonstrated a significant decrease in condylar volume from pre-treatment to 3 months post-treatment (Phase P1, P\u0026thinsp;=\u0026thinsp;0.006). No significant change was observed between 3 and 6 months (Phase P2, P\u0026thinsp;=\u0026thinsp;0.977), followed by a significant increase from 6 months to 1 year (Phase P3, P\u0026thinsp;=\u0026thinsp;0.005). Bone formation predominantly occurred in regions covered by the articular disc, with significant differences in root mean square (RMS) values between disc-covered and non-disc-covered areas (P\u0026thinsp;=\u0026thinsp;0.012).\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eThese findings indicate that condylar remodeling is most active during the first 3 months following conservative treatment of pediatric SFMC and that the TMJ disc plays a critical role in this process.\u003c/p\u003e\u003ch2\u003eClinical relevance:\u003c/h2\u003e \u003cp\u003eClinical prognostic studies on sagittal condylar fractures in children can assist clinicians in more accurately assessing fracture severity, selecting the most appropriate treatment strategies, reducing the incidence of complications, and ultimately improving overall treatment outcomes in pediatric patients.\u003c/p\u003e","manuscriptTitle":"Three-dimensional Spatiotemporal Analysis of Condylar Remodeling After Conservative Treatment of Pediatric Mandibular Condylar Sagittal Fractures","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-25 05:37:16","doi":"10.21203/rs.3.rs-8806987/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-03-20T14:44:18+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-23T09:36:21+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-22T16:12:48+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"69131093212435091808753703298305532496","date":"2026-02-21T15:15:15+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-19T08:25:21+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"264086364871910506166548113208218919066","date":"2026-02-19T07:27:18+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"334389764150790674873028982630126228490","date":"2026-02-18T20:10:52+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-02-17T13:27:23+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-02-09T05:47:32+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-02-09T05:43:39+00:00","index":"","fulltext":""},{"type":"submitted","content":"Clinical Oral Investigations","date":"2026-02-06T11:55:32+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"clinical-oral-investigations","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"cloi","sideBox":"Learn more about [Clinical Oral Investigations](http://link.springer.com/journal/784)","snPcode":"784","submissionUrl":"https://submission.nature.com/new-submission/784/3","title":"Clinical Oral Investigations","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"a9588c3e-129f-4b78-aeff-d3667443e7fd","owner":[],"postedDate":"February 25th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-06T09:54:02+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-25 05:37:16","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8806987","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8806987","identity":"rs-8806987","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}