Characteristics of the Mandibular Canal in the Mandibular Angle Area and Its Significance in Minimally Invasive Treatment of Mandibular Angle Fractures

Characteristics of the Mandibular Canal in the Mandibular Angle Area and Its Significance in Minimally Invasive Treatment of Mandibular Angle 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 Characteristics of the Mandibular Canal in the Mandibular Angle Area and Its Significance in Minimally Invasive Treatment of Mandibular Angle Fractures Lifeng Li, Kiran Acharya, Jingyi Shi, Junbo Tu, Chengqun Hou, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4428182/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Objective To explore the clinical significance of the characteristics of the mandibular canal in the mandibular angle area by measuring its position, with a focus on minimally invasive treatment of mandibular angle fractures. Methods Sixty individuals in good health, who received cone-beam computed tomography (CBCT) scans at the Stomatological Hospital of Xi'an Jiaotong University, were chosen for evaluation. Measurements were taken of the distances between the mandibular canal and the external oblique ridge, mandibular angle, and cortical bone on the buccal side. Statistical analysis was conducted to explore the positioning trends of the mandibular canal and to discern any gender-based disparities. Results The average distance from the mandibular canal to the external oblique ridge in the mandibular angle region was 14.41 ± 2.41 mm, and the average distance from the mandibular canal to the buccal cortical thickness was 4.67 ± 1.20 mm. A notable statistical contrast was observed in the distance from the mandibular canal to the mandibular angle between males and females (P 0.05). Conclusion The distance from the mandibular canal to the external oblique ridge remains consistent, showing no statistical variance between genders. For safer management of mandibular angle fractures through minimally invasive techniques, it's recommended to maintain a minimum distance of 17 mm between internal fixation screws and the external oblique line to prevent injury to the inferior alveolar nerve. Moreover, the proximity of the canal to the buccal cortical bone is relatively short, suggesting that conventional single-cortical screws may not adequately mitigate the risk of nerve injury. Cone-beam computed tomography mandibular canal inferior alveolar nerve mandibular angle fractures Figures Figure 1 Figure 2 Figure 3 Figure 4 1. Introduction Mandibular fractures are common traumatic injuries in the maxillofacial area, with mandibular angle fractures comprising over 30% of cases[ 1 ]. The prevailing treatment typically involves open reduction and rigid internal fixation surgery, reserving conservative methods for minimally displaced fractures[ 2 ]. Traditional surgical techniques for mandibular angle fractures employ a submandibular approach. While this approach provides excellent visibility and ensures reliable reduction and fixation, it results in a visible scar beneath the chin, impacting aesthetics. Furthermore, there's a risk of temporary or permanent deviation of the lower lip or corner of the mouth due to injury to the mandibular branch of the mental nerve. Additionally, adequate exposure of fracture ends often necessitates severing the attachments of the masseter muscle, leading to temporary limitations in mouth opening and affecting chewing function postoperatively. With the advancement of minimally invasive surgical techniques, scholars often favor an approach for treating mandibular angle fractures involving an intraoral vestibular incision combined with a transbuccal incision, typically requiring the placement of two small bone plates for fixation. One plate is situated at the external oblique line, while the other is positioned as closely as feasible to the lower border of the mandible. This approach conceals the intraoral mucosal incision, shortening the path to the bone surface, thus minimizing damage to vital vessels and nerves, reducing surgical trauma and time. The transbuccal incision, following facial skin lines, results in minor scars, notably decreasing the risk of facial nerve damage. Nevertheless, this minimally invasive method has its limitations. While the transbuccal approach permits adequate traction of facial soft tissues with transbuccal instruments, the surgical field within the mouth is restricted. This limited view impedes both assessing the extent of fracture reduction and determining the placement of bone plates, especially the plate near the mandible's lower border. It's not uncommon in clinical practice to encounter bone plates used for fixation crossing or overlapping with the mandibular canal in the mandibular angle area, potentially leading to inferior alveolar nerve damage and causing varying degrees of physical and mental health impairment in patients. Traditional anatomical knowledge outlines the general trajectory of the mandibular canal, but specific data regarding its relevance to minimally invasive treatment of mandibular angle fractures are scarce. Hence, investigating the characteristics of the mandibular canal in the mandibular angle region holds significant clinical importance. This study aimed to measure and analyze the mandibular canal's position in healthy adults to elucidate its clinical relevance in mitigating complications within this area. 2. Data and Methods 2.1 Clinical Data : The study comprised sixty healthy adults who met the selection criteria and underwent CBCT at Stomatological hospital, Xi'an Jiaotong University including 50 males and 10 females, with ages ranging from 22 to 56 years and an average age of 39 years. Inclusion criteria encompassed subjects without systemic diseases, significant lesions, or facial deformities in both mandibles, possessing normal occlusion, devoid of substantial alveolar bone absorption, and lacking lateral chewing habits. Exclusion criteria involved individuals with missing or significantly tilted mandibular first or second molars and those with a history of orthodontic treatment. The Ethics Committee of Xi'an Jiaotong University Stomatological Hospital approved this study. 1.2 Methods : CBCT was performed on all 60 subjects using a Korean-made Vatech cone-beam CT machine with the following parameters: 7 mA, 90 kV, 0.3 mm scan layer thickness, 30 s exposure time, scanning range covering the entire mandible, image reconstruction interval of 0.1 mm, subjects in an upright relaxed position, fixed head position, facial midline perpendicular to the ground, and orbits-ears plane parallel to the ground. CBCT images were saved as Dicom files and measured using EZ3D software. All CBCT image data were marked by the same oral and maxillofacial surgeon using EZ3D software to indicate the mandibular canal in the mandibular angle area. The measurement plane was adjusted to the transverse section position for measurement: an imaginary intersection point formed by the posterior edge tangent of the mandibular ramus and the inferior edge tangent of the mandible, connected to the distal mesial cusp of the mandibular second molar to form an imaginary line. The measurement plane in this study passed through the imaginary line connecting both sides of the mandible. The following data were measured on this plane: distance from the mandibular canal to the external oblique line (L1), distance from the mandibular canal to the mandibular angle (L2), buccal cortical thickness of the mandibular canal (W1), and mandibular thickness at the mandibular canal (W2). All data were measured three times by the same person for each subject and averaged, with a one-week interval between measurements to reduce measurement errors. 2.3 Statistical Analysis : Data analysis was performed using SPSS 17.0 statistical software, and independent sample t-tests were used to analyze the mean values and their relationship with gender, with P < 0.05 considered statistically significant. 3. Results The mean distance from the mandibular canal to the external oblique line in the mandibular angle area was 14.41 ± 2.41 mm; the mean distance from the mandibular canal to the mandibular angle was 14.41 ± 2.41 mm; the mean distance from the mandibular canal to the buccal cortical thickness was 4.67 ± 1.20 mm; and the mean mandibular thickness at the mandibular canal was 16.15 ± 2.66 mm. There was a statistically significant difference in the distance from the mandibular canal to the mandibular angle between males and females (P 0.05). Table 1 Comparison of the location characteristics of the mandibular canal in the mandibular angle area in genders Distance from Mandibular Canal to External Oblique Line (mm) Distance from Mandibular Canal to Mandibular Angle (mm) Distance from Mandibular Canal to Buccal Cortical Bone (mm) The average thickness of the mandible at the location of the mandibular canal(mm) Male 14.41 ± 2.41 21.27 ± 3.38 4.67 ± 1.20 9.68 ± 1.74 Female 14.40 ± 1.96 18.50 ± 2.81 4.68 ± 1.01 9.16 ± 1.29 P value 0.988 0.018 0.988 0.376 4. Discussion Clinically, the traditional approach for treating mandibular angle fractures involved a submandibular incision. This method required making an incision below the mandible, cutting through the skin and platysma muscle, and proceeding upwards along the deep surface of the platysma to the lower border of the mandible. The masseter muscle was then detached to fully expose the fracture site for anatomical reduction. While this approach provided excellent visibility and facilitated straightforward and reliable surgery, it left a noticeable scar, significantly impacting aesthetics, and carried the risk of damaging the marginal mandibular branch of the facial nerve. This could lead to complications such as postoperative deviation of the corner of the mouth on the affected side. In recent years, the adoption of minimally invasive techniques has increased, with an intraoral approach combined with a transbuccal incision gaining attention for the reduction and internal fixation of mandibular angle fractures. The transbuccal approach avoids the noticeable skin scars and the risk of damaging the marginal mandibular branch of the facial nerve associated with the traditional submandibular approach. However, the limited surgical visibility and operational space in this method often lead to complications such as injury to the inferior alveolar nerve due to the placement of the osteosynthesis plate, especially near the lower border of the mandible, resulting in numbness in the lower lip. Therefore, accurately measuring and analyzing the depth of the mandibular nerve canal and the thickness of the buccal cortical bone in the mandibular angle region is crucial. The mandibular nerve canal is a critical anatomical structure within the mandible that houses the inferior alveolar neurovascular bundle. It begins at the mandibular foramen, travels forward and downward through the ramus, and runs almost horizontally within the body of the mandible[ 3 ]. At the apex of the second premolar, part of the neurovascular bundle exits through the mental foramen to supply the labial gingiva of the first premolar and anterior teeth, the lower lip, and the chin. The remainder continues anteriorly within the mandibular canal to supply the first premolar, canine, and incisors. Studies indicate that the mandibular nerve canal follows three "closer" patterns: 1. closer to the inner cortical plate than the outer cortical plate. 2. Closer to the anterior border of the mandibular ramus than the posterior border. 3. Closer to the lower border of the mandible than the alveolar border. Various clinical procedures can potentially damage the inferior alveolar nerve, including molar treatments, extractions—especially of impacted teeth—and firm internal fixation[ 4 – 10 ]. Such injuries can cause numbness in the lower lip, leading to significant inconvenience for patients. Traditional anatomical descriptions provide a general overview of the mandibular nerve canal's trajectory. However, there is a need for simple and practical data specifically tailored for minimally invasive treatments of mandibular angle fractures. The mandibular angle region, a common site for fractures, refers to the triangular area bordered by the anterior and posterior attachments of the masseter muscle, typically located distal to the third molar. This area is subject to high stress, making it a frequent fracture site. Although the mandibular angle can resist rotational forces effectively, the region from the posterior molar triangle to the anterior masseter attachment is relatively weak. The presence of impacted third molars or unerupted tooth buds further exacerbates this weakness by reducing bone height, making it more susceptible to fractures under lateral force. The mandibular angle has thin cross-sections, thick cortices, and a poor blood supply. Combined with the presence of the third molar, these factors lead to higher postoperative complications. Mandibular angle fractures typically present with pain, swelling, and significant limitation of mouth opening. If the fracture displacement damages the inferior alveolar nerve, patients may experience numbness in the lower lip and gingiva. For surgical repair, the bone in the external oblique ridge area is thicker and preferred for placing the first fixation plate due to its tensile strength. The lower border of the mandible, being a compressive stress trajectory area, is another critical site for placing the second fixation plate [ 11 , 12 ]. While placing and securing both plates is straightforward with a submandibular approach, the transbuccal minimally, invasive approach poses significant challenges for placing the plate near the lower border of the mandible. This is due to limited surgical visibility and operational space, making accurate placement more difficult and increasing the risk of complications such as inferior alveolar nerve injury[ 13 ]. Titanium alloy plates are the most commonly used materials for the fixation of mandibular fractures, known for their reliability in bearing masticatory pressure. Screws are employed to secure these plates to the bone, making it crucial to understand the distance from the mandibular cortex to the nerve canal to prevent nerve damage. Screws must not be too long to avoid injuring important structures, nor too short to ensure the stability of the titanium plate. Therefore, when performing open reduction and internal fixation of mandibular angle fractures, it is essential to understand the trajectory of the mandibular nerve canal and its proximity to the buccal cortical bone, especially in the absence of preoperative CBCT imaging. Measuring and analyzing the average distance from the mandibular nerve canal to the external oblique ridge and buccal cortex provides critical data to guide the safe placement of plates and screws, thus reducing the risk of inferior alveolar nerve injury. In this study, the average distance from the mandibular nerve canal to the external oblique ridge in the mandibular angle region was found to be 14.41 ± 2.41 mm, and the average distance to the buccal cortex was 4.67 ± 1.20 mm, with no statistically significant differences between genders. Therefore, during open reduction and internal fixation of mandibular angle fractures, after fixing the tensile band plate on the external oblique ridge, the placement of the compression band plate below it should be at least 17 mm away from the external oblique ridge to ensure safety. The length of the screws, to avoid damaging the inferior alveolar nerve, should theoretically be less than 3.4 mm. This recommended length is considerably shorter than the shortest screws typically used in clinical practice, indicating that, in the absence of clear preoperative knowledge of the nerve canal's trajectory, surgeons should avoid taking risks with screw length in the compression band area and opt for fixation in relatively safer zones. The measurement plane used in this study was designed to standardize measurements, representing an "ideal" fracture line in the mandibular angle region. While the location of the fracture line in actual clinical practice can vary, the trajectory of the mandibular nerve canal in this region does not show sudden directional changes. Small fixation plates often require at least four screws, which would overlap with part of the measurement plane in this study. Therefore, the data obtained provide valuable references for the fixation of non-"ideal" mandibular angle fractures as well. Although the positional data of the mandibular nerve canal found in this study are relatively consistent, and the sample primarily consisted of males—reflecting the general occurrence pattern of mandibular fractures—the sample size was not large enough to allow for further subdivision by race, region, and nutritional factors. Therefore, more reliable conclusions will require further multicenter studies with larger sample sizes. 5. Conclusion Indeed, comprehending the characteristics of the mandibular canal in the mandibular angle region holds crucial clinical significance for the minimally invasive treatment of mandibular angle fractures. This understanding serves as a guiding light for surgeons, aiding in the reduction of the risk of inferior alveolar nerve injury and enhancing the safety and effectiveness of surgical interventions in this anatomical area. Declarations A. Ethical Approval and Consent to participant Guidelines - This research experiment is carried out on the humans according to the relevant guidelines and regulation approved by Clinical Research Center of Shaanxi Province for Dental and Maxillofacial Diseases, College of Stomatology, Xi’an Jiaotong University. Ethical Approval - This research is approved by ethical committee of Stomatology hospital of Xian Jiaotong university. Consent to participant- It is confirmed that written and informed consent was obtained from all the subjects and/ or their legal guardian(s). B. Consent for publication Not applicable. C. Availability of data and materials : All relevant datasets and their supporting information files generated and/or analyzed during this study are available from the corresponding author upon reasonable request. D. Competing interests No competing interests exist. E. Funding This study was supported in part by the National Key Research and Development Program of China(2019YFB1311604) and The Key Research and Development Program of Shaanxi (Program No. 2020SF-182). F. Acknowledgment We would like to express our sincere gratitude to our co-authors, other members of Clinical Research Center of Shaanxi Province for Dental and Maxillofacial Diseases, College of Stomatology, Xi’an Jiaotong University for their invaluable contributions to this article. Their expertise and insights have greatly improved the quality of our research, and their support and encouragement have been instrumental in completing this project. We are fortunate to have had the opportunity to work with such talented colleagues and we thank them for their dedication and commitment to this work. G. Authors Contribution AUTHORS Conception and design of study/review/case series Acquisition of data: laboratory or clinical/literature search Analysis and interpretation of data collected Drafting of article and/or critical revision Final approval and guarantor of manuscript Lifeng Li ✓ ✓ ✓ ✓ Kiran Acharya ✓ ✓ ✓ Jingyi Shi ✓ ✓ Junbo Tu ✓ ✓ Chengqun Hou ✓ ✓ Xiaoyi Hu ✓ ✓ ✓ ✓ References Rashid A, et al. Incidence and patterns of mandibular fractures during a 5-year period in a London teaching hospital. Br J Oral Maxillofac Surg. 2013;51(8):794–8. Braasch DC, Abubaker AO. Management of mandibular angle fracture. Oral Maxillofacial Surg Clin. 2013;25(4):591–600. de Oliveira Júnior MR, et al. Morphometrical analysis of the human mandibular canal: a CT investigation. Surg radiologic anatomy: SRA. 2011;33(4):345–52. Pogrel MA. Damage to the inferior alveolar nerve as the result of root canal therapy. J Am Dent Assoc. 2007;138(1):65–9. Jun SH, et al. Anatomical differences in lower third molars visualized by 2D and 3D X-ray imaging: clinical outcomes after extraction. Int J Oral Maxillofac Surg. 2013;42(4):489–96. Dannan A. Traumatic Injury of the Inferior Alveolar Nerve after Dental Implant Surgery; a Literature Review. Internet J Dent Sci, 2013. 12. Jerjes W, et al. Permanent sensory nerve impairment following third molar surgery: a prospective study. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2006;102(4):e1–7. Gomes AC, et al. Sensitivity and specificity of pantomography to predict inferior alveolar nerve damage during extraction of impacted lower third molars. J Oral Maxillofac Surg. 2008;66(2):256–9. Hasegawa T, et al. Risk factors associated with inferior alveolar nerve injury after extraction of the mandibular third molar–a comparative study of preoperative images by panoramic radiography and computed tomography. Int J Oral Maxillofac Surg. 2013;42(7):843–51. Park W, et al. Cortical integrity of the inferior alveolar canal as a predictor of paresthesia after third-molar extraction. J Am Dent Assoc. 2010;141(3):271–8. Naghipur S, Shah A, Elgazzar RF. Does the presence or position of lower third molars alter the risk of mandibular angle or condylar fractures? J Oral Maxillofac Surg. 2014;72(9):1766–72. Borgonovo AE, et al. CBCT evaluation of the tridimensional relationship between impacted lower third molar and the inferior alveolar nerve position. Minerva Stomatol. 2017;66(1):9–19. Singh RK, et al. Role of fixation in posttraumatic nerve injury recovery in displaced mandibular angle fracture. Natl J Maxillofac Surg. 2016;7(1):29–32. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4428182","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":310139559,"identity":"712c6415-1303-4c26-bde7-d575c419acec","order_by":0,"name":"Lifeng Li","email":"","orcid":"","institution":"Xi'an Jiaotong University","correspondingAuthor":false,"prefix":"","firstName":"Lifeng","middleName":"","lastName":"Li","suffix":""},{"id":310139560,"identity":"e138c540-b07b-4247-8b45-8f047cb8219a","order_by":1,"name":"Kiran Acharya","email":"","orcid":"","institution":"Xi'an Jiaotong University","correspondingAuthor":false,"prefix":"","firstName":"Kiran","middleName":"","lastName":"Acharya","suffix":""},{"id":310139561,"identity":"37b78ddd-6adb-476b-88cb-cf8eacad78c2","order_by":2,"name":"Jingyi Shi","email":"","orcid":"","institution":"Xi'an Jiaotong University","correspondingAuthor":false,"prefix":"","firstName":"Jingyi","middleName":"","lastName":"Shi","suffix":""},{"id":310139562,"identity":"2c619bdb-860c-44bc-a16a-b9f0e7541a4b","order_by":3,"name":"Junbo Tu","email":"","orcid":"","institution":"Xi'an Jiaotong University","correspondingAuthor":false,"prefix":"","firstName":"Junbo","middleName":"","lastName":"Tu","suffix":""},{"id":310139563,"identity":"0dfd6fab-2e7c-485a-8e9e-b61fadf8a6b0","order_by":4,"name":"Chengqun Hou","email":"","orcid":"","institution":"Xi'an Jiaotong University","correspondingAuthor":false,"prefix":"","firstName":"Chengqun","middleName":"","lastName":"Hou","suffix":""},{"id":310139564,"identity":"84b82c4e-e14b-40ce-8464-07bd85ce389c","order_by":5,"name":"Xiaoyi Hu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA1ElEQVRIiWNgGAWjYDCCA1CSn4EhAcRibCBCC0jRAQbJBobEBtK0GEAYRGjhO978/MHHPXcSN99IeP6Yh8FGdsMB5mcP8GmRPHPMsHHGs2eJ284cSGzmYUgz3nCAzdwAnxaDGzmMzTwHDiduO94A0nI4ccMBHjYJorRsbmYAaflPgpYN7GBbDhDWAvLLzBkHDhvPAPpl5hyDZOOZh9nM8GoBhtiDDx8OHJbtn5GT8OFNhZ1s3/HmZ3i1IAGeBKA7gTQzkeqBgP0A8WpHwSgYBaNgRAEAHBxXdNE+fwoAAAAASUVORK5CYII=","orcid":"","institution":"Xi'an Jiaotong University","correspondingAuthor":true,"prefix":"","firstName":"Xiaoyi","middleName":"","lastName":"Hu","suffix":""}],"badges":[],"createdAt":"2024-05-16 03:36:10","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4428182/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4428182/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":57948505,"identity":"42f8d09c-d986-4e9f-a6ba-193406ac69e4","added_by":"auto","created_at":"2024-06-07 20:38:04","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":253268,"visible":true,"origin":"","legend":"\u003cp\u003eThe distance between the mandibular canal and the oblique line.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-4428182/v1/4ac3a4cdf30adcf496af73ad.png"},{"id":57948508,"identity":"b4abe466-173d-4dcb-a32b-2f20bfd9fc2c","added_by":"auto","created_at":"2024-06-07 20:38:04","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":258157,"visible":true,"origin":"","legend":"\u003cp\u003eThe distance between the mandibular canal and lower edge of the mandibular angle.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-4428182/v1/2b6619d5256502e24de00aca.png"},{"id":57948506,"identity":"ad611afb-8c1f-4011-a4ad-bfbd23fd32d3","added_by":"auto","created_at":"2024-06-07 20:38:04","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":99548,"visible":true,"origin":"","legend":"\u003cp\u003eThe distance of the mandibular canal between buccal cortex.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-4428182/v1/38dffc483ca4f6118c2f1d54.png"},{"id":57948507,"identity":"38f40da2-9d7e-4fc9-ba4e-a49f2e28bf27","added_by":"auto","created_at":"2024-06-07 20:38:04","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":97785,"visible":true,"origin":"","legend":"\u003cp\u003eThe thickness of the mandible at the mandibular canal.\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-4428182/v1/4446b0257e4e8d1b71d9693a.png"},{"id":61142259,"identity":"d652d099-ab4a-4ca3-956e-33da1a30a5f9","added_by":"auto","created_at":"2024-07-26 07:14:25","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1076060,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4428182/v1/0356e919-7cfe-4d09-a79d-99a3f69126a3.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Characteristics of the Mandibular Canal in the Mandibular Angle Area and Its Significance in Minimally Invasive Treatment of Mandibular Angle Fractures","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eMandibular fractures are common traumatic injuries in the maxillofacial area, with mandibular angle fractures comprising over 30% of cases[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. The prevailing treatment typically involves open reduction and rigid internal fixation surgery, reserving conservative methods for minimally displaced fractures[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Traditional surgical techniques for mandibular angle fractures employ a submandibular approach. While this approach provides excellent visibility and ensures reliable reduction and fixation, it results in a visible scar beneath the chin, impacting aesthetics. Furthermore, there's a risk of temporary or permanent deviation of the lower lip or corner of the mouth due to injury to the mandibular branch of the mental nerve. Additionally, adequate exposure of fracture ends often necessitates severing the attachments of the masseter muscle, leading to temporary limitations in mouth opening and affecting chewing function postoperatively.\u003c/p\u003e \u003cp\u003eWith the advancement of minimally invasive surgical techniques, scholars often favor an approach for treating mandibular angle fractures involving an intraoral vestibular incision combined with a transbuccal incision, typically requiring the placement of two small bone plates for fixation. One plate is situated at the external oblique line, while the other is positioned as closely as feasible to the lower border of the mandible. This approach conceals the intraoral mucosal incision, shortening the path to the bone surface, thus minimizing damage to vital vessels and nerves, reducing surgical trauma and time. The transbuccal incision, following facial skin lines, results in minor scars, notably decreasing the risk of facial nerve damage. Nevertheless, this minimally invasive method has its limitations. While the transbuccal approach permits adequate traction of facial soft tissues with transbuccal instruments, the surgical field within the mouth is restricted. This limited view impedes both assessing the extent of fracture reduction and determining the placement of bone plates, especially the plate near the mandible's lower border. It's not uncommon in clinical practice to encounter bone plates used for fixation crossing or overlapping with the mandibular canal in the mandibular angle area, potentially leading to inferior alveolar nerve damage and causing varying degrees of physical and mental health impairment in patients.\u003c/p\u003e \u003cp\u003eTraditional anatomical knowledge outlines the general trajectory of the mandibular canal, but specific data regarding its relevance to minimally invasive treatment of mandibular angle fractures are scarce. Hence, investigating the characteristics of the mandibular canal in the mandibular angle region holds significant clinical importance. This study aimed to measure and analyze the mandibular canal's position in healthy adults to elucidate its clinical relevance in mitigating complications within this area.\u003c/p\u003e"},{"header":"2. Data and Methods","content":"\u003cp\u003e \u003cb\u003e2.1 Clinical Data\u003c/b\u003e: The study comprised sixty healthy adults who met the selection criteria and underwent CBCT at Stomatological hospital, Xi'an Jiaotong University including 50 males and 10 females, with ages ranging from 22 to 56 years and an average age of 39 years.\u003c/p\u003e \u003cp\u003eInclusion criteria encompassed subjects without systemic diseases, significant lesions, or facial deformities in both mandibles, possessing normal occlusion, devoid of substantial alveolar bone absorption, and lacking lateral chewing habits.\u003c/p\u003e \u003cp\u003eExclusion criteria involved individuals with missing or significantly tilted mandibular first or second molars and those with a history of orthodontic treatment.\u003c/p\u003e \u003cp\u003e The Ethics Committee of Xi'an Jiaotong University Stomatological Hospital approved this study.\u003c/p\u003e \u003cp\u003e \u003cb\u003e1.2 Methods\u003c/b\u003e: CBCT was performed on all 60 subjects using a Korean-made Vatech cone-beam CT machine with the following parameters: 7 mA, 90 kV, 0.3 mm scan layer thickness, 30 s exposure time, scanning range covering the entire mandible, image reconstruction interval of 0.1 mm, subjects in an upright relaxed position, fixed head position, facial midline perpendicular to the ground, and orbits-ears plane parallel to the ground. CBCT images were saved as Dicom files and measured using EZ3D software.\u003c/p\u003e \u003cp\u003eAll CBCT image data were marked by the same oral and maxillofacial surgeon using EZ3D software to indicate the mandibular canal in the mandibular angle area. The measurement plane was adjusted to the transverse section position for measurement: an imaginary intersection point formed by the posterior edge tangent of the mandibular ramus and the inferior edge tangent of the mandible, connected to the distal mesial cusp of the mandibular second molar to form an imaginary line. The measurement plane in this study passed through the imaginary line connecting both sides of the mandible. The following data were measured on this plane: distance from the mandibular canal to the external oblique line (L1), distance from the mandibular canal to the mandibular angle (L2), buccal cortical thickness of the mandibular canal (W1), and mandibular thickness at the mandibular canal (W2). All data were measured three times by the same person for each subject and averaged, with a one-week interval between measurements to reduce measurement errors.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003e2.3 Statistical Analysis\u003c/b\u003e: Data analysis was performed using SPSS 17.0 statistical software, and independent sample t-tests were used to analyze the mean values and their relationship with gender, with P\u0026thinsp;\u0026lt;\u0026thinsp;0.05 considered statistically significant.\u003c/p\u003e"},{"header":"3. Results","content":"\u003cp\u003eThe mean distance from the mandibular canal to the external oblique line in the mandibular angle area was 14.41\u0026thinsp;\u0026plusmn;\u0026thinsp;2.41 mm; the mean distance from the mandibular canal to the mandibular angle was 14.41\u0026thinsp;\u0026plusmn;\u0026thinsp;2.41 mm; the mean distance from the mandibular canal to the buccal cortical thickness was 4.67\u0026thinsp;\u0026plusmn;\u0026thinsp;1.20 mm; and the mean mandibular thickness at the mandibular canal was 16.15\u0026thinsp;\u0026plusmn;\u0026thinsp;2.66 mm. There was a statistically significant difference in the distance from the mandibular canal to the mandibular angle between males and females (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05), while the other measured parameters showed no statistically significant differences between genders (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of the location characteristics of the mandibular canal in the mandibular angle area in genders\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDistance from Mandibular Canal to External Oblique Line (mm)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDistance from Mandibular Canal to Mandibular Angle (mm)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eDistance from Mandibular Canal to Buccal Cortical Bone (mm)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eThe average thickness of the mandible at the location of the mandibular canal(mm)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14.41\u0026thinsp;\u0026plusmn;\u0026thinsp;2.41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e21.27\u0026thinsp;\u0026plusmn;\u0026thinsp;3.38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4.67\u0026thinsp;\u0026plusmn;\u0026thinsp;1.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e9.68\u0026thinsp;\u0026plusmn;\u0026thinsp;1.74\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14.40\u0026thinsp;\u0026plusmn;\u0026thinsp;1.96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18.50\u0026thinsp;\u0026plusmn;\u0026thinsp;2.81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4.68\u0026thinsp;\u0026plusmn;\u0026thinsp;1.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e9.16\u0026thinsp;\u0026plusmn;\u0026thinsp;1.29\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.988\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.018\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.988\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.376\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eClinically, the traditional approach for treating mandibular angle fractures involved a submandibular incision. This method required making an incision below the mandible, cutting through the skin and platysma muscle, and proceeding upwards along the deep surface of the platysma to the lower border of the mandible. The masseter muscle was then detached to fully expose the fracture site for anatomical reduction. While this approach provided excellent visibility and facilitated straightforward and reliable surgery, it left a noticeable scar, significantly impacting aesthetics, and carried the risk of damaging the marginal mandibular branch of the facial nerve. This could lead to complications such as postoperative deviation of the corner of the mouth on the affected side. In recent years, the adoption of minimally invasive techniques has increased, with an intraoral approach combined with a transbuccal incision gaining attention for the reduction and internal fixation of mandibular angle fractures. The transbuccal approach avoids the noticeable skin scars and the risk of damaging the marginal mandibular branch of the facial nerve associated with the traditional submandibular approach. However, the limited surgical visibility and operational space in this method often lead to complications such as injury to the inferior alveolar nerve due to the placement of the osteosynthesis plate, especially near the lower border of the mandible, resulting in numbness in the lower lip. Therefore, accurately measuring and analyzing the depth of the mandibular nerve canal and the thickness of the buccal cortical bone in the mandibular angle region is crucial.\u003c/p\u003e \u003cp\u003eThe mandibular nerve canal is a critical anatomical structure within the mandible that houses the inferior alveolar neurovascular bundle. It begins at the mandibular foramen, travels forward and downward through the ramus, and runs almost horizontally within the body of the mandible[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. At the apex of the second premolar, part of the neurovascular bundle exits through the mental foramen to supply the labial gingiva of the first premolar and anterior teeth, the lower lip, and the chin. The remainder continues anteriorly within the mandibular canal to supply the first premolar, canine, and incisors. Studies indicate that the mandibular nerve canal follows three \"closer\" patterns: 1. closer to the inner cortical plate than the outer cortical plate. 2. Closer to the anterior border of the mandibular ramus than the posterior border. 3. Closer to the lower border of the mandible than the alveolar border. Various clinical procedures can potentially damage the inferior alveolar nerve, including molar treatments, extractions\u0026mdash;especially of impacted teeth\u0026mdash;and firm internal fixation[\u003cspan additionalcitationids=\"CR5 CR6 CR7 CR8 CR9\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Such injuries can cause numbness in the lower lip, leading to significant inconvenience for patients.\u003c/p\u003e \u003cp\u003eTraditional anatomical descriptions provide a general overview of the mandibular nerve canal's trajectory. However, there is a need for simple and practical data specifically tailored for minimally invasive treatments of mandibular angle fractures.\u003c/p\u003e \u003cp\u003eThe mandibular angle region, a common site for fractures, refers to the triangular area bordered by the anterior and posterior attachments of the masseter muscle, typically located distal to the third molar. This area is subject to high stress, making it a frequent fracture site. Although the mandibular angle can resist rotational forces effectively, the region from the posterior molar triangle to the anterior masseter attachment is relatively weak. The presence of impacted third molars or unerupted tooth buds further exacerbates this weakness by reducing bone height, making it more susceptible to fractures under lateral force.\u003c/p\u003e \u003cp\u003eThe mandibular angle has thin cross-sections, thick cortices, and a poor blood supply. Combined with the presence of the third molar, these factors lead to higher postoperative complications. Mandibular angle fractures typically present with pain, swelling, and significant limitation of mouth opening. If the fracture displacement damages the inferior alveolar nerve, patients may experience numbness in the lower lip and gingiva. For surgical repair, the bone in the external oblique ridge area is thicker and preferred for placing the first fixation plate due to its tensile strength. The lower border of the mandible, being a compressive stress trajectory area, is another critical site for placing the second fixation plate [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. While placing and securing both plates is straightforward with a submandibular approach, the transbuccal minimally, invasive approach poses significant challenges for placing the plate near the lower border of the mandible. This is due to limited surgical visibility and operational space, making accurate placement more difficult and increasing the risk of complications such as inferior alveolar nerve injury[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eTitanium alloy plates are the most commonly used materials for the fixation of mandibular fractures, known for their reliability in bearing masticatory pressure. Screws are employed to secure these plates to the bone, making it crucial to understand the distance from the mandibular cortex to the nerve canal to prevent nerve damage. Screws must not be too long to avoid injuring important structures, nor too short to ensure the stability of the titanium plate. Therefore, when performing open reduction and internal fixation of mandibular angle fractures, it is essential to understand the trajectory of the mandibular nerve canal and its proximity to the buccal cortical bone, especially in the absence of preoperative CBCT imaging. Measuring and analyzing the average distance from the mandibular nerve canal to the external oblique ridge and buccal cortex provides critical data to guide the safe placement of plates and screws, thus reducing the risk of inferior alveolar nerve injury. In this study, the average distance from the mandibular nerve canal to the external oblique ridge in the mandibular angle region was found to be 14.41\u0026thinsp;\u0026plusmn;\u0026thinsp;2.41 mm, and the average distance to the buccal cortex was 4.67\u0026thinsp;\u0026plusmn;\u0026thinsp;1.20 mm, with no statistically significant differences between genders. Therefore, during open reduction and internal fixation of mandibular angle fractures, after fixing the tensile band plate on the external oblique ridge, the placement of the compression band plate below it should be at least 17 mm away from the external oblique ridge to ensure safety. The length of the screws, to avoid damaging the inferior alveolar nerve, should theoretically be less than 3.4 mm. This recommended length is considerably shorter than the shortest screws typically used in clinical practice, indicating that, in the absence of clear preoperative knowledge of the nerve canal's trajectory, surgeons should avoid taking risks with screw length in the compression band area and opt for fixation in relatively safer zones. The measurement plane used in this study was designed to standardize measurements, representing an \"ideal\" fracture line in the mandibular angle region. While the location of the fracture line in actual clinical practice can vary, the trajectory of the mandibular nerve canal in this region does not show sudden directional changes. Small fixation plates often require at least four screws, which would overlap with part of the measurement plane in this study. Therefore, the data obtained provide valuable references for the fixation of non-\"ideal\" mandibular angle fractures as well.\u003c/p\u003e \u003cp\u003eAlthough the positional data of the mandibular nerve canal found in this study are relatively consistent, and the sample primarily consisted of males\u0026mdash;reflecting the general occurrence pattern of mandibular fractures\u0026mdash;the sample size was not large enough to allow for further subdivision by race, region, and nutritional factors. Therefore, more reliable conclusions will require further multicenter studies with larger sample sizes.\u003c/p\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003eIndeed, comprehending the characteristics of the mandibular canal in the mandibular angle region holds crucial clinical significance for the minimally invasive treatment of mandibular angle fractures. This understanding serves as a guiding light for surgeons, aiding in the reduction of the risk of inferior alveolar nerve injury and enhancing the safety and effectiveness of surgical interventions in this anatomical area.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eA.\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eEthical Approval and Consent to participant\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eGuidelines - This research experiment is carried out on the humans according to the relevant guidelines and regulation approved by\u0026nbsp;Clinical Research Center of Shaanxi Province for Dental and\u0026nbsp;Maxillofacial Diseases, College of Stomatology, Xi\u0026rsquo;an Jiaotong\u0026nbsp;University.\u003c/p\u003e\n\u003cp\u003eEthical Approval - This research is approved by ethical committee of Stomatology hospital of Xian Jiaotong university.\u003c/p\u003e\n\u003cp\u003eConsent to participant- It is confirmed that written and informed consent was obtained from all the subjects and/ or their legal guardian(s).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eB. Consent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eC. Availability of data and materials\u003c/strong\u003e:\u003c/p\u003e\n\u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;All relevant datasets and their supporting information files generated and/or analyzed during this study are available from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eD. Competing interests\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo competing interests exist.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eE. Funding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was supported in part by the National Key\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003eResearch and Development Program of China(2019YFB1311604) and\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eThe Key Research and Development Program of Shaanxi (Program No. 2020SF-182).\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003eF. Acknowledgment\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe would like to express our sincere gratitude to our co-authors, other members of\u0026nbsp;Clinical Research Center of Shaanxi Province for Dental and\u0026nbsp;Maxillofacial Diseases, College of Stomatology, Xi\u0026rsquo;an Jiaotong\u0026nbsp;University\u0026nbsp;for their invaluable contributions to this article. Their expertise and insights have greatly improved the quality of our research, and their support and encouragement have been instrumental in completing this project. We are fortunate to have had the opportunity to work with such talented colleagues and we thank them for their dedication and commitment to this work.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eG. Authors Contribution\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"702\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"18.945868945868945%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;AUTHORS\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.66096866096866%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eConception and design of study/review/case series\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.37891737891738%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eAcquisition of data: laboratory or clinical/literature search\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.814814814814815%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eAnalysis \u0026nbsp;and interpretation of data collected\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.54131054131054%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eDrafting of article and/or critical revision\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.65811965811966%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eFinal approval and guarantor\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eof manuscript\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"18.945868945868945%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eLifeng Li\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.66096866096866%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e✓\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.37891737891738%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e✓\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.814814814814815%\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"10.54131054131054%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e✓\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.65811965811966%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e✓\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"18.945868945868945%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eKiran Acharya\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.66096866096866%\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"17.37891737891738%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e✓\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.814814814814815%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e✓\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.54131054131054%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e✓\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.65811965811966%\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"18.945868945868945%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eJingyi Shi\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.66096866096866%\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"17.37891737891738%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e✓\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.814814814814815%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e✓\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.54131054131054%\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"19.65811965811966%\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"18.945868945868945%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eJunbo Tu\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.66096866096866%\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"17.37891737891738%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e✓\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.814814814814815%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e✓\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.54131054131054%\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"19.65811965811966%\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"18.945868945868945%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eChengqun Hou\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.66096866096866%\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"17.37891737891738%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e✓\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.814814814814815%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e✓\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.54131054131054%\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"19.65811965811966%\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"18.945868945868945%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eXiaoyi Hu\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.66096866096866%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e✓\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.37891737891738%\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"14.814814814814815%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e✓\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.54131054131054%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e✓\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.65811965811966%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e✓\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eRashid A, et al. Incidence and patterns of mandibular fractures during a 5-year period in a London teaching hospital. Br J Oral Maxillofac Surg. 2013;51(8):794\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBraasch DC, Abubaker AO. Management of mandibular angle fracture. Oral Maxillofacial Surg Clin. 2013;25(4):591\u0026ndash;600.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ede Oliveira J\u0026uacute;nior MR, et al. Morphometrical analysis of the human mandibular canal: a CT investigation. Surg radiologic anatomy: SRA. 2011;33(4):345\u0026ndash;52.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePogrel MA. Damage to the inferior alveolar nerve as the result of root canal therapy. J Am Dent Assoc. 2007;138(1):65\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJun SH, et al. Anatomical differences in lower third molars visualized by 2D and 3D X-ray imaging: clinical outcomes after extraction. Int J Oral Maxillofac Surg. 2013;42(4):489\u0026ndash;96.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDannan A. Traumatic Injury of the Inferior Alveolar Nerve after Dental Implant Surgery; a Literature Review. Internet J Dent Sci, 2013. 12.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJerjes W, et al. Permanent sensory nerve impairment following third molar surgery: a prospective study. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2006;102(4):e1\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGomes AC, et al. Sensitivity and specificity of pantomography to predict inferior alveolar nerve damage during extraction of impacted lower third molars. J Oral Maxillofac Surg. 2008;66(2):256\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHasegawa T, et al. Risk factors associated with inferior alveolar nerve injury after extraction of the mandibular third molar\u0026ndash;a comparative study of preoperative images by panoramic radiography and computed tomography. Int J Oral Maxillofac Surg. 2013;42(7):843\u0026ndash;51.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePark W, et al. Cortical integrity of the inferior alveolar canal as a predictor of paresthesia after third-molar extraction. J Am Dent Assoc. 2010;141(3):271\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNaghipur S, Shah A, Elgazzar RF. Does the presence or position of lower third molars alter the risk of mandibular angle or condylar fractures? J Oral Maxillofac Surg. 2014;72(9):1766\u0026ndash;72.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBorgonovo AE, et al. CBCT evaluation of the tridimensional relationship between impacted lower third molar and the inferior alveolar nerve position. Minerva Stomatol. 2017;66(1):9\u0026ndash;19.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSingh RK, et al. Role of fixation in posttraumatic nerve injury recovery in displaced mandibular angle fracture. Natl J Maxillofac Surg. 2016;7(1):29\u0026ndash;32.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Cone-beam computed tomography, mandibular canal, inferior alveolar nerve, mandibular angle fractures","lastPublishedDoi":"10.21203/rs.3.rs-4428182/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4428182/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eObjective\u003c/h2\u003e \u003cp\u003eTo explore the clinical significance of the characteristics of the mandibular canal in the mandibular angle area by measuring its position, with a focus on minimally invasive treatment of mandibular angle fractures.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eSixty individuals in good health, who received cone-beam computed tomography (CBCT) scans at the Stomatological Hospital of Xi'an Jiaotong University, were chosen for evaluation. Measurements were taken of the distances between the mandibular canal and the external oblique ridge, mandibular angle, and cortical bone on the buccal side. Statistical analysis was conducted to explore the positioning trends of the mandibular canal and to discern any gender-based disparities.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThe average distance from the mandibular canal to the external oblique ridge in the mandibular angle region was 14.41\u0026thinsp;\u0026plusmn;\u0026thinsp;2.41 mm, and the average distance from the mandibular canal to the buccal cortical thickness was 4.67\u0026thinsp;\u0026plusmn;\u0026thinsp;1.20 mm. A notable statistical contrast was observed in the distance from the mandibular canal to the mandibular angle between males and females (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Conversely, there were no statistically significant differences between genders for the other measured parameters (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eThe distance from the mandibular canal to the external oblique ridge remains consistent, showing no statistical variance between genders. For safer management of mandibular angle fractures through minimally invasive techniques, it's recommended to maintain a minimum distance of 17 mm between internal fixation screws and the external oblique line to prevent injury to the inferior alveolar nerve. Moreover, the proximity of the canal to the buccal cortical bone is relatively short, suggesting that conventional single-cortical screws may not adequately mitigate the risk of nerve injury.\u003c/p\u003e","manuscriptTitle":"Characteristics of the Mandibular Canal in the Mandibular Angle Area and Its Significance in Minimally Invasive Treatment of Mandibular Angle Fractures","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-06-07 20:37:59","doi":"10.21203/rs.3.rs-4428182/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"8ba81e2a-95ec-4595-bc78-b793601116db","owner":[],"postedDate":"June 7th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-07-26T07:06:18+00:00","versionOfRecord":[],"versionCreatedAt":"2024-06-07 20:37:59","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4428182","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4428182","identity":"rs-4428182","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}