Root position relative to the mandibular canal is the dominant predictor of cortical wall defects in impacted mandibular third molars: a CBCT-based retrospective study in a Middle-Eastern cohort

Root position relative to the mandibular canal is the dominant predictor of cortical wall defects in impacted mandibular third molars: a CBCT-based retrospective study in a Middle-Eastern cohort | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Root position relative to the mandibular canal is the dominant predictor of cortical wall defects in impacted mandibular third molars: a CBCT-based retrospective study in a Middle-Eastern cohort Mohammed Hadi Al‑Quhali, Majdi Khaled Jubari, Salah M. Bin Hafedh This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8360194/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 Objectives: To quantify the association between mandibular third molar (MTM) root position relative to the mandibular canal (MC) and MC cortical wall defects on cone‑beam CT (CBCT), and to explore impaction‑type and age correlates. Materials and methods: Retrospective cross‑sectional analysis of impacted MTMs (n=344) from private radiology centers in Yemen. Variables: coronal‑plane root position (superior/buccal/lingual), Winter angulation and Pell & Gregory depth, MC wall integrity (intact vs defective), and orthopantomogram (OPG) warning signs (interrupted white line, diversion, narrowing). Associations were evaluated with chi‑square tests (α=0.05). (Figure 2). MC integrity by position: superior intact 94/128 (73.4%); buccal intact 18/66 (27.3%), defects 48/66 (72.7%); lingual intact 95/150 (63.3%); χ² p<0.001 (Figure 1). Conclusions: Buccal root position was the dominant predictor of MC cortical wall defects, followed by lingual; superior roots were least risky. Findings support selective CBCT when OPG suggests close MTM–MC proximity to guide nerve‑sparing strategies (e.g., coronectomy) in high‑risk anatomy. Clinical relevance: CBCT refines risk stratification beyond OPG when bucco‑lingual relationships are uncertain and may influence the choice of nerve‑sparing techniques. Health sciences/Anatomy Health sciences/Diseases Health sciences/Health care Health sciences/Medical research mandibular third molar inferior alveolar nerve mandibular canal CBCT cortical wall defect coronectomy panoramic radiography Figures Figure 1 Figure 2 Introduction Inferior alveolar nerve (IAN) injury is a principal concern in mandibular third molar (MTM) surgery. Classical panoramic (OPG) warning signs—such as interruption of the canal’s white line, diversion/narrowing of the canal, and darkening/deflection of roots—are associated with close MTM–MC proximity and higher risk of nerve exposure [ 1 , 7 , 8 ]. However, OPG cannot reliably resolve the bucco‑lingual relationship. CBCT provides multiplanar assessment of root‑canal spatial relationships and cortical integrity and is recommended selectively when OPG suggests proximity or when 3‑D information will alter the surgical plan [ 2 – 6 ]. This study reports population‑specific prevalence of CBCT‑verified MC cortical defects adjacent to impacted MTMs, and quantifies the association between coronal‑plane root position (superior, buccal, lingual) and MC cortical integrity. (Fig. 2 ). Materials and Methods Study design and setting We performed a retrospective cross‑sectional analysis of CBCT volumes (2022–2024) from private radiology centers in Sana’a, Yemen. Eligibility included adults with fully formed MTM roots and diagnostic‑quality CBCTs encompassing the inferior alveolar canal (IAC); scans with metallic artifacts or confounding pathology were excluded. CBCT justification followed international guidance on selective use and radiation protection [3]. Ethics approval and adherence to guidelines: This retrospective analysis of anonymized CBCT datasets was approved by the University of Science and Technology Research Ethics Committee, Sana’a, Yemen (Study ID 1447/0073/UREC/UST; approval date 04-12-2025). All methods were performed in accordance with relevant institutional and national guidelines and regulations and with the principles of the Declaration of Helsinki. The requirement for individual informed consent was waived by the Ethics Committee because only de-identified imaging data acquired previously for diagnostic purposes were used. Image evaluation Volumes were reviewed in axial, sagittal, and coronal planes by calibrated examiners. We recorded age, sex, Winter angulation (vertical, mesioangular, horizontal, distoangular), Pell & Gregory depth (A/B/C), root position relative to the MC (superior, buccal, lingual), and MC wall integrity (intact vs defective). Standard OPG signs (interrupted white line, canal diversion, canal narrowing) were scored on reconstructed panoramic views [1,7,8]. (Figure 2). Outcomes and statistics The primary outcome was MC wall integrity on CBCT. Descriptive statistics summarized distributions, and associations (root position vs integrity; impaction variables vs integrity) were evaluated with chi‑square tests (α=0.05). Selective CBCT for equivocal/high‑risk OPG findings is consistent with prior evidence on diagnostic accuracy and clinical utility [2,4,5,8,9]. Results Sample characteristics: 344 impacted MTMs met inclusion. Winter classification: vertical 130 (38%), mesioangular 124 (36%), horizontal 59 (17%), distoangular 31 (9%). Pell & Gregory depth: A 170 (49.4%), B 139 (40.4%), C 35 (10.2%). MC integrity by position: superior intact 94/128 (73.4%); buccal intact 18/66 (27.3%), defects 48/66 (72.7%); lingual intact 95/150 (63.3%); χ² p < 0.001 (Fig. 1 ). OPG descriptors: Interruption of the canal’s white line was present in 260/344 with 133/260 (51.2%) defects on CBCT; canal diversion present in 8/344 (100% defects); canal narrowing present in 20/344 (30% defects). These patterns are consistent with prior reports of asymmetric predictive value of OPG signs for IAN risk [ 1 , 7 , 8 ]. (Fig. 2 ). See Table 1 (Winter distribution), Table 2 (Pell & Gregory depth), Table 3 (MC integrity by root position), and Table 4 (OPG features vs MC integrity). Figures are supplied separately. Table 1 Winter classification of impaction (n = 344) Impaction type n % Vertical 130 38.0 Mesioangular 124 36.0 Horizontal 59 17.1 Distoangular 31 9.0 Table 2 Pell & Gregory depth classification (n = 344) Depth level n % A (High) 170 49.4 B (Medium) 139 40.4 C (Low) 35 10.2 Table 3 Mandibular canal wall integrity by CBCT root position (n = 344) Root position n Intact Defective Defective % Root within canal (n) Superior 128 94 34 26.6 — Buccal 66 18 48 72.7 — Lingual 150 95 55 36.7 — Total 344 207 137 39.8 71 Table 4 OPG features (present) and CBCT‑confirmed canal defects OPG feature (present) n (present) Defects (n) Defect % Interrupted white line (present) 260 133 51.2 Diversion of canal (present) 8 8 100.0 Narrowing of canal (present) 20 6 30.0 Complete white line (present) 84 4 4.8 Discussion Principal findings: Buccal root position relative to the MC was strongly associated with CBCT‑confirmed cortical wall defects; lingual positioning carried intermediate risk, while superior positioning was comparatively protective. This gradient aligns with prior CBCT‑based studies and reviews demonstrating superior delineation of root–canal relationships versus OPG and frequent impact on surgical planning [ 2 , 4 , 5 , 8 , 9 ]. Clinical implications: When OPG reveals high‑risk features (e.g., interrupted white line, canal diversion/narrowing), selective CBCT is warranted to guide nerve‑sparing strategies such as precise sectioning or coronectomy [ 6 , 10 , 11 ]. This approach balances diagnostic value with radiation protection principles [ 3 ]. (Fig. 2 ). Limitations: Retrospective design and absence of postoperative neurosensory outcomes; OPG signs were scored on reconstructions rather than dedicated exposures. Prospective studies linking CBCT risk phenotypes to postoperative nerve outcomes are warranted [ 9 , 16 ]. Conclusions In this Middle‑Eastern cohort, buccal root position was the dominant predictor of CBCT‑confirmed MC cortical wall defects, followed by lingual; superior roots were least risky. Selective CBCT is justified where OPG suggests close MTM–MC proximity or where 3‑D mapping is likely to change treatment. Declarations Compliance with ethical standards Ethics approval: University of Science and Technology Research Ethics Committee, Study ID 1447/0073/UREC/UST, approved 04-12-2025 (retrospective analysis of anonymized imaging; consent waived). Competing interests: The authors declare no competing interests. Funding: None. Author contributions: M.H. Al‑Quhali—conceptualization, data curation, drafting; M.K. Jubari—supervision, clinical interpretation, critical revision; S.M. Bin Hafedh—statistics, interpretation, critical revision. All authors approved the final manuscript and agree to be accountable for all aspects of the work. Data availability: All de-identified datasets generated and/or analysed during the current study are available from the corresponding author on reasonable request, in line with institutional and national regulations governing clinical imaging data. References Rood JP, Shehab BAAN. The radiological prediction of inferior alveolar nerve injury during third molar surgery. Br J Oral Maxillofac Surg. 1990;28(1):20–25. Available from: https://www.sciencedirect.com/science/article/pii/0266435690900056 Matzen LH, Wenzel A. Efficacy of CBCT for assessment of impacted mandibular third molars: review based on a hierarchical model of evidence. Dentomaxillofac Radiol. 2015;44(1):20140189. Available from: https://academic.oup.com/dmfr/article-abstract/44/1/20140189/7263899 SEDENTEXCT Consortium. Radiation Protection No. 172: Cone Beam CT for Dental and Maxillofacial Radiology—Evidence‑based Guidelines. European Commission; 2012. Available from: https://sedentexct.eu/files/radiation_protection_172.pdf Ghaeminia H, Meijer GJ, Soehardi A, Borstlap WA, Mulder J, Bergé SJ. The use of CBCT for removal of wisdom teeth changes the surgical approach compared with panoramic radiography: pilot study. Int J Oral Maxillofac Surg. 2011;40(8):834–839. Available from: https://www.sciencedirect.com/science/article/pii/S0901502711001184 Reia VCB, Telles‑Araujo GT, Peralta‑Mamani M, Biancardi MR, Rubira CMF, Rubira‑Bullen IRF. Diagnostic accuracy of CBCT vs panoramic radiography in predicting IAN exposure: systematic review and meta‑analysis. Clin Oral Investig. 2021;25(10):5699–5713. doi:10.1007/s00784-021-03942-4 American Association of Oral and Maxillofacial Surgeons (AAOMS). Management of Third Molar Teeth (White Paper). 2022. Available from: https://aaoms.org/wp-content/uploads/2022/06/management_third_molar_white_paper.pdf Sedaghatfar M, August MA, Dodson TB. Panoramic findings as predictors of inferior alveolar nerve exposure after third molar extraction. J Oral Maxillofac Surg. 2005;63(11):1479–1485. Available from: https://www.sciencedirect.com/science/article/pii/S0278239104012650 Tantanapornkul W, Okouchi K, Fujiwara Y, et al. Comparison of panoramic radiography and computed tomography for determining the relationship of the IAN to mandibular third molars. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2007;103(2):253–259. Available from: https://www.sciencedirect.com/science/article/pii/S1079210406007692 Petersen LB, Vaeth M, Wenzel A. Neurosensoric disturbances after third molar surgery based on either panoramic imaging or CBCT: randomized controlled trial. Dentomaxillofac Radiol. 2016;45(2):20150224. Available from: https://www.birpublications.org/doi/10.1259/dmfr.20150224 Leung YY, Cheung LK. Safety of coronectomy versus excision of wisdom teeth: randomized controlled trial. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2009;108(6):821–827. Available from: https://www.sciencedirect.com/science/article/abs/pii/S1079210409004624 Long H, Zhou Y, Liao L, Pyakurel U, Wang Y, Lai W. Coronectomy vs total removal for high‑risk third molars: systematic review. J Oral Maxillofac Surg. 2012;70(1):4–13. doi:10.1016/j.joms.2011.03.051 Scarfe WC, Farman AG, Sukovic P. Clinical applications of cone‑beam computed tomography in dental practice. J Can Dent Assoc. 2006;72(1):75–80. Available from: https://jcda.ca/article/b75 Kim ST, Hu KS, Song WC, et al. Location of the mandibular canal and patterns of impaction. Clin Anat. 2009;22(5):557–567. doi:10.1002/ca.20708 Valmaseda‑Castellón E, Berini‑Aytés L, Gay‑Escoda C. Inferior alveolar nerve damage after lower third molar extraction: prospective study of 1,117 extractions. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2001;92(4):377–383. doi:10.1067/moe.2001.118367 de Melo Albert DG, Gomes AC, Hummig KL, et al. Accuracy of CBCT for predicting IAN exposure: systematic review. J Craniomaxillofac Surg. 2019;47(5):768–775. doi:10.1016/j.jcms.2019.02.020 Matzen LH, Christensen J, Wenzel A. Patients’ risk of nerve injury after MTM removal based on OPG vs CBCT. Oral Surg Oral Med Oral Pathol Oral Radiol. 2013;115(4):463–470. Available from: https://www.sciencedirect.com/science/article/pii/S2212440313000332 Gadiwalla Y, Shah N, Renton T, et al. Review of national and international third molar guidelines. Int J Oral Maxillofac Surg. 2021;50(5):691–698. doi:10.1016/j.ijom.2020.05.013 Kapila SD, Nervina JM. CBCT in orthodontics: indications and hazards. Semin Orthod. 2015;21(3):152–160. Available from: https://www.sciencedirect.com/science/article/pii/S1073874615000474 Ludlow JB, Timothy R, Walker C, Hunter R, Benavides E, Samuelson DB, et al. Effective dose of dental CBCT: meta‑analysis. Dentomaxillofac Radiol. 2015;44(1):20140197. Available from: https://academic.oup.com/dmfr/article/44/1/20140197/7263895 Guerrero ME, Noriega J, Castro C, et al. Relationship between mandibular third molars and mandibular canal using CBCT. Oral Surg Oral Med Oral Pathol Oral Radiol. 2012;114(5 Suppl):S34–S41. Available from: https://www.sciencedirect.com/science/article/pii/S2212440312003239 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-8360194","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":563732031,"identity":"57e30bab-b939-4def-bcd7-10858b77ce48","order_by":0,"name":"Mohammed Hadi Al‑Quhali","email":"","orcid":"","institution":"University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Mohammed","middleName":"Hadi","lastName":"Al‑Quhali","suffix":""},{"id":563732036,"identity":"a542ebae-1ea1-4127-b1e3-cb1b7b0baea1","order_by":1,"name":"Majdi Khaled Jubari","email":"","orcid":"","institution":"Sana'a University","correspondingAuthor":false,"prefix":"","firstName":"Majdi","middleName":"Khaled","lastName":"Jubari","suffix":""},{"id":563732038,"identity":"b9f36712-5ff4-4fd0-9c19-6b9c878a37cd","order_by":2,"name":"Salah M. Bin Hafedh","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABAElEQVRIie3RMWrDMBSA4Sc8eHnQjioadAWFgqC0JVexMWRyaKfWo4LBXZRkzUm81kHQKQcwqENNIVOHQBfTZqhCuto4W6H6Qdo+pCcB+Hx/skAFABWECiTshhFyJFiBJKuTSYBDAH9azz7v4ZVjmJfvN18lB5pU0GZlJxGbOGcr2I40vjxeThd2pOgkInpjuwnEiiEY8kxTyabaRuM6FQEpuglfNvm3I2PNPyS7cgTo3a6XQB0Xh1NiTVEyaA8khV4i6qa4RmESjZOHi7lys+BWrPtm4cvEWMzMrQ5NSdu95RAmzVub9Vzs9xGOkcJt55H7puHt3To7Bfh8Pt9/6AeyMljrg5+bbAAAAABJRU5ErkJggg==","orcid":"","institution":"Sana'a University","correspondingAuthor":true,"prefix":"","firstName":"Salah","middleName":"M. Bin","lastName":"Hafedh","suffix":""}],"badges":[],"createdAt":"2025-12-14 20:38:24","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8360194/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8360194/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":99316539,"identity":"8083954c-4aaa-4995-89d6-e6dbfa8fde97","added_by":"auto","created_at":"2025-12-31 16:28:34","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":29406,"visible":true,"origin":"","legend":"","description":"","filename":"Manuscriptrevised.docx","url":"https://assets-eu.researchsquare.com/files/rs-8360194/v1/66aee634aa3ffb30aac5b5f9.docx"},{"id":99317275,"identity":"180d72d0-3f8d-444a-a11a-b1e4bf07337b","added_by":"auto","created_at":"2025-12-31 16:29:53","extension":"png","order_by":1,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":255169,"visible":true,"origin":"","legend":"","description":"","filename":"Fig1.png","url":"https://assets-eu.researchsquare.com/files/rs-8360194/v1/c25d938441221a240c24a9e1.png"},{"id":99189187,"identity":"588106f1-227e-4196-be06-d2ea0577926e","added_by":"auto","created_at":"2025-12-30 00:24:50","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":37443,"visible":true,"origin":"","legend":"","description":"","filename":"Tables.docx","url":"https://assets-eu.researchsquare.com/files/rs-8360194/v1/be7eb21aa465c278f85fdcc3.docx"},{"id":99189192,"identity":"68c2a2e5-ac72-445a-9197-549d946c08ca","added_by":"auto","created_at":"2025-12-30 00:24:50","extension":"png","order_by":3,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":239721,"visible":true,"origin":"","legend":"","description":"","filename":"Fig2.png","url":"https://assets-eu.researchsquare.com/files/rs-8360194/v1/6c99f1d6a0bc2f459f180097.png"},{"id":99189190,"identity":"d074cca9-879a-42e5-9f09-63fcad3d49ee","added_by":"auto","created_at":"2025-12-30 00:24:50","extension":"docx","order_by":4,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":36820,"visible":true,"origin":"","legend":"","description":"","filename":"FigureLegends.docx","url":"https://assets-eu.researchsquare.com/files/rs-8360194/v1/6576becbbc7a4c69a2992e20.docx"},{"id":99317285,"identity":"fbbd681b-999b-46a9-97ca-8ef73c979696","added_by":"auto","created_at":"2025-12-31 16:29:54","extension":"json","order_by":5,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":5546,"visible":true,"origin":"","legend":"","description":"","filename":"7ea8805ae0a542988e61f4200d502069.json","url":"https://assets-eu.researchsquare.com/files/rs-8360194/v1/12b5e7abc3f4abe3e1f86f5b.json"},{"id":99318626,"identity":"08397b23-d8ac-4e0d-a4b0-198a8d9b5627","added_by":"auto","created_at":"2025-12-31 16:33:47","extension":"xml","order_by":6,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":52192,"visible":true,"origin":"","legend":"","description":"","filename":"7ea8805ae0a542988e61f4200d5020691enriched.xml","url":"https://assets-eu.researchsquare.com/files/rs-8360194/v1/4b9112ad6f5315614ca51e25.xml"},{"id":99318254,"identity":"1efe7938-5baa-410d-ba3d-74bf097472ee","added_by":"auto","created_at":"2025-12-31 16:32:25","extension":"png","order_by":7,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":255169,"visible":true,"origin":"","legend":"","description":"","filename":"Fig1.png","url":"https://assets-eu.researchsquare.com/files/rs-8360194/v1/83792a116b6a8eee4e524836.png"},{"id":99189199,"identity":"721fe320-ac3b-4f0c-a4d5-bc50c31e1e7c","added_by":"auto","created_at":"2025-12-30 00:24:50","extension":"png","order_by":8,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":239721,"visible":true,"origin":"","legend":"","description":"","filename":"Fig2.png","url":"https://assets-eu.researchsquare.com/files/rs-8360194/v1/90b011644019e10aaf8475cd.png"},{"id":99189197,"identity":"e1c79bef-07e2-4616-baa7-9e39423905a6","added_by":"auto","created_at":"2025-12-30 00:24:50","extension":"png","order_by":9,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":47007,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig1.png","url":"https://assets-eu.researchsquare.com/files/rs-8360194/v1/88c04fcd1dce44290b970e52.png"},{"id":99189194,"identity":"e2b67e4f-aa87-4480-bac9-2d5621c9495e","added_by":"auto","created_at":"2025-12-30 00:24:50","extension":"png","order_by":10,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":43788,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig2.png","url":"https://assets-eu.researchsquare.com/files/rs-8360194/v1/fc6b6a4251c3ce0e25e39672.png"},{"id":99318245,"identity":"8ed1ac4a-d87b-48bf-b073-7f1771ca51e6","added_by":"auto","created_at":"2025-12-31 16:32:23","extension":"xml","order_by":11,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":47991,"visible":true,"origin":"","legend":"","description":"","filename":"7ea8805ae0a542988e61f4200d5020691structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8360194/v1/74d37c5fe0199773986718bb.xml"},{"id":99189193,"identity":"e07ca235-2047-4ae8-892f-ac0e1b02b776","added_by":"auto","created_at":"2025-12-30 00:24:50","extension":"html","order_by":12,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":58848,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8360194/v1/4769eec7492806fb1abfaa0b.html"},{"id":99316260,"identity":"3ee5294b-8301-4301-a3b4-150faa50b59c","added_by":"auto","created_at":"2025-12-31 16:28:01","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":255169,"visible":true,"origin":"","legend":"\u003cp\u003eDefect rate by root position relative to the mandibular canal (CBCT). Bars show percentage of canals with cortical defects for buccal, lingual, and superior root positions.\u003c/p\u003e","description":"","filename":"Fig1.png","url":"https://assets-eu.researchsquare.com/files/rs-8360194/v1/d39a54b149dabd91a69ebe47.png"},{"id":99189185,"identity":"d6a447b7-b961-4459-be33-af9caafe595f","added_by":"auto","created_at":"2025-12-30 00:24:50","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":239721,"visible":true,"origin":"","legend":"\u003cp\u003eDefect rate on CBCT when OPG warning signs are present. Bars show the percentage of canals with cortical defects when the OPG shows an interrupted white line, canal diversion, or canal narrowing.\u003c/p\u003e","description":"","filename":"Fig2.png","url":"https://assets-eu.researchsquare.com/files/rs-8360194/v1/efd4c83e83c7c6eab8b7e538.png"},{"id":99789334,"identity":"c5f997e3-57c1-4212-80e0-b46f4b346591","added_by":"auto","created_at":"2026-01-08 12:49:25","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1020998,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8360194/v1/a4db2b91-5fb1-4abf-af08-e339a1464ef7.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Root position relative to the mandibular canal is the dominant predictor of cortical wall defects in impacted mandibular third molars: a CBCT-based retrospective study in a Middle-Eastern cohort","fulltext":[{"header":"Introduction","content":"\u003cp\u003eInferior alveolar nerve (IAN) injury is a principal concern in mandibular third molar (MTM) surgery. Classical panoramic (OPG) warning signs\u0026mdash;such as interruption of the canal\u0026rsquo;s white line, diversion/narrowing of the canal, and darkening/deflection of roots\u0026mdash;are associated with close MTM\u0026ndash;MC proximity and higher risk of nerve exposure [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. However, OPG cannot reliably resolve the bucco‑lingual relationship. CBCT provides multiplanar assessment of root‑canal spatial relationships and cortical integrity and is recommended selectively when OPG suggests proximity or when 3‑D information will alter the surgical plan [\u003cspan additionalcitationids=\"CR3 CR4 CR5\" citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. This study reports population‑specific prevalence of CBCT‑verified MC cortical defects adjacent to impacted MTMs, and quantifies the association between coronal‑plane root position (superior, buccal, lingual) and MC cortical integrity. (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003e\u003cstrong\u003eStudy design and setting\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe performed a retrospective cross‑sectional analysis of CBCT volumes (2022\u0026ndash;2024) from private radiology centers in Sana\u0026rsquo;a, Yemen. Eligibility included adults with fully formed MTM roots and diagnostic‑quality CBCTs encompassing the inferior alveolar canal (IAC); scans with metallic artifacts or confounding pathology were excluded. CBCT justification followed international guidance on selective use and radiation protection [3].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and adherence to guidelines:\u0026nbsp;\u003c/strong\u003eThis retrospective analysis of anonymized CBCT datasets was approved by the University of Science and Technology Research Ethics Committee, Sana\u0026rsquo;a, Yemen (Study ID 1447/0073/UREC/UST; approval date 04-12-2025). All methods were performed in accordance with relevant institutional and national guidelines and regulations and with the principles of the Declaration of Helsinki. The requirement for individual informed consent was waived by the Ethics Committee because only de-identified imaging data acquired previously for diagnostic purposes were used.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eImage evaluation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eVolumes were reviewed in axial, sagittal, and coronal planes by calibrated examiners. We recorded age, sex, Winter angulation (vertical, mesioangular, horizontal, distoangular), Pell \u0026amp; Gregory depth (A/B/C), root position relative to the MC (superior, buccal, lingual), and MC wall integrity (intact vs defective). Standard OPG signs (interrupted white line, canal diversion, canal narrowing) were scored on reconstructed panoramic views [1,7,8]. (Figure 2).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eOutcomes and statistics\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe primary outcome was MC wall integrity on CBCT. Descriptive statistics summarized distributions, and associations (root position vs integrity; impaction variables vs integrity) were evaluated with chi‑square tests (\u0026alpha;=0.05). Selective CBCT for equivocal/high‑risk OPG findings is consistent with prior evidence on diagnostic accuracy and clinical utility [2,4,5,8,9].\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eSample characteristics: 344 impacted MTMs met inclusion. Winter classification: vertical 130 (38%), mesioangular 124 (36%), horizontal 59 (17%), distoangular 31 (9%). Pell \u0026amp; Gregory depth: A 170 (49.4%), B 139 (40.4%), C 35 (10.2%).\u003c/p\u003e \u003cp\u003eMC integrity by position: superior intact 94/128 (73.4%); buccal intact 18/66 (27.3%), defects 48/66 (72.7%); lingual intact 95/150 (63.3%); χ\u0026sup2; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001 (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eOPG descriptors: Interruption of the canal\u0026rsquo;s white line was present in 260/344 with 133/260 (51.2%) defects on CBCT; canal diversion present in 8/344 (100% defects); canal narrowing present in 20/344 (30% defects). These patterns are consistent with prior reports of asymmetric predictive value of OPG signs for IAN risk [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eSee Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e (Winter distribution), Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e (Pell \u0026amp; Gregory depth), Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e (MC integrity by root position), and Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e (OPG features vs MC integrity). Figures are supplied separately.\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\u003eWinter classification of impaction (n\u0026thinsp;=\u0026thinsp;344)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eImpaction type\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e%\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVertical\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e130\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e38.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMesioangular\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e124\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e36.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHorizontal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e17.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDistoangular\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e9.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePell \u0026amp; Gregory depth classification (n\u0026thinsp;=\u0026thinsp;344)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDepth level\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e%\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA (High)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e170\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e49.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eB (Medium)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e139\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e40.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC (Low)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e10.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMandibular canal wall integrity by CBCT root position (n\u0026thinsp;=\u0026thinsp;344)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRoot position\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eIntact\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eDefective\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eDefective %\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eRoot within canal (n)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSuperior\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e128\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e26.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBuccal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e66\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e72.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLingual\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e150\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e36.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e344\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e207\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e137\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e39.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e71\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eOPG features (present) and CBCT‑confirmed canal defects\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOPG feature (present)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003en (present)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDefects (n)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eDefect %\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInterrupted white line (present)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e260\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e133\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e51.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDiversion of canal (present)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e100.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNarrowing of canal (present)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e30.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComplete white line (present)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e84\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.8\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":"Discussion","content":"\u003cp\u003ePrincipal findings: Buccal root position relative to the MC was strongly associated with CBCT‑confirmed cortical wall defects; lingual positioning carried intermediate risk, while superior positioning was comparatively protective. This gradient aligns with prior CBCT‑based studies and reviews demonstrating superior delineation of root\u0026ndash;canal relationships versus OPG and frequent impact on surgical planning [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eClinical implications: When OPG reveals high‑risk features (e.g., interrupted white line, canal diversion/narrowing), selective CBCT is warranted to guide nerve‑sparing strategies such as precise sectioning or coronectomy [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. This approach balances diagnostic value with radiation protection principles [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eLimitations: Retrospective design and absence of postoperative neurosensory outcomes; OPG signs were scored on reconstructions rather than dedicated exposures. Prospective studies linking CBCT risk phenotypes to postoperative nerve outcomes are warranted [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn this Middle‑Eastern cohort, buccal root position was the dominant predictor of CBCT‑confirmed MC cortical wall defects, followed by lingual; superior roots were least risky. Selective CBCT is justified where OPG suggests close MTM\u0026ndash;MC proximity or where 3‑D mapping is likely to change treatment.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eCompliance with ethical standards\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEthics approval: University of Science and Technology Research Ethics Committee, Study ID 1447/0073/UREC/UST, approved 04-12-2025 (retrospective analysis of anonymized imaging; consent waived).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests:\u003c/strong\u003e The authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e None.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions:\u0026nbsp;\u003c/strong\u003eM.H. Al‑Quhali\u0026mdash;conceptualization, data curation, drafting; M.K. Jubari\u0026mdash;supervision, clinical interpretation, critical revision; S.M. Bin Hafedh\u0026mdash;statistics, interpretation, critical revision. All authors approved the final manuscript and agree to be accountable for all aspects of the work.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability:\u0026nbsp;\u003c/strong\u003eAll de-identified datasets generated and/or analysed during the current study are available from the corresponding author on reasonable request, in line with institutional and national regulations governing clinical imaging data.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eRood JP, Shehab BAAN. The radiological prediction of inferior alveolar nerve injury during third molar surgery. Br J Oral Maxillofac Surg. 1990;28(1):20\u0026ndash;25. Available from: https://www.sciencedirect.com/science/article/pii/0266435690900056\u003c/li\u003e\n\u003cli\u003eMatzen LH, Wenzel A. Efficacy of CBCT for assessment of impacted mandibular third molars: review based on a hierarchical model of evidence. Dentomaxillofac Radiol. 2015;44(1):20140189. Available from: https://academic.oup.com/dmfr/article-abstract/44/1/20140189/7263899\u003c/li\u003e\n\u003cli\u003eSEDENTEXCT Consortium. Radiation Protection No. 172: Cone Beam CT for Dental and Maxillofacial Radiology\u0026mdash;Evidence‑based Guidelines. European Commission; 2012. Available from: https://sedentexct.eu/files/radiation_protection_172.pdf\u003c/li\u003e\n\u003cli\u003eGhaeminia H, Meijer GJ, Soehardi A, Borstlap WA, Mulder J, Berg\u0026eacute; SJ. The use of CBCT for removal of wisdom teeth changes the surgical approach compared with panoramic radiography: pilot study. Int J Oral Maxillofac Surg. 2011;40(8):834\u0026ndash;839. Available from: https://www.sciencedirect.com/science/article/pii/S0901502711001184\u003c/li\u003e\n\u003cli\u003eReia VCB, Telles‑Araujo GT, Peralta‑Mamani M, Biancardi MR, Rubira CMF, Rubira‑Bullen IRF. Diagnostic accuracy of CBCT vs panoramic radiography in predicting IAN exposure: systematic review and meta‑analysis. Clin Oral Investig. 2021;25(10):5699\u0026ndash;5713. doi:10.1007/s00784-021-03942-4\u003c/li\u003e\n\u003cli\u003eAmerican Association of Oral and Maxillofacial Surgeons (AAOMS). Management of Third Molar Teeth (White Paper). 2022. Available from: https://aaoms.org/wp-content/uploads/2022/06/management_third_molar_white_paper.pdf\u003c/li\u003e\n\u003cli\u003eSedaghatfar M, August MA, Dodson TB. Panoramic findings as predictors of inferior alveolar nerve exposure after third molar extraction. J Oral Maxillofac Surg. 2005;63(11):1479\u0026ndash;1485. Available from: https://www.sciencedirect.com/science/article/pii/S0278239104012650\u003c/li\u003e\n\u003cli\u003eTantanapornkul W, Okouchi K, Fujiwara Y, et al. Comparison of panoramic radiography and computed tomography for determining the relationship of the IAN to mandibular third molars. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2007;103(2):253\u0026ndash;259. Available from: https://www.sciencedirect.com/science/article/pii/S1079210406007692\u003c/li\u003e\n\u003cli\u003ePetersen LB, Vaeth M, Wenzel A. Neurosensoric disturbances after third molar surgery based on either panoramic imaging or CBCT: randomized controlled trial. Dentomaxillofac Radiol. 2016;45(2):20150224. Available from: https://www.birpublications.org/doi/10.1259/dmfr.20150224\u003c/li\u003e\n\u003cli\u003eLeung YY, Cheung LK. Safety of coronectomy versus excision of wisdom teeth: randomized controlled trial. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2009;108(6):821\u0026ndash;827. Available from: https://www.sciencedirect.com/science/article/abs/pii/S1079210409004624\u003c/li\u003e\n\u003cli\u003eLong H, Zhou Y, Liao L, Pyakurel U, Wang Y, Lai W. Coronectomy vs total removal for high‑risk third molars: systematic review. J Oral Maxillofac Surg. 2012;70(1):4\u0026ndash;13. doi:10.1016/j.joms.2011.03.051\u003c/li\u003e\n\u003cli\u003eScarfe WC, Farman AG, Sukovic P. Clinical applications of cone‑beam computed tomography in dental practice. J Can Dent Assoc. 2006;72(1):75\u0026ndash;80. Available from: https://jcda.ca/article/b75\u003c/li\u003e\n\u003cli\u003eKim ST, Hu KS, Song WC, et al. Location of the mandibular canal and patterns of impaction. Clin Anat. 2009;22(5):557\u0026ndash;567. doi:10.1002/ca.20708\u003c/li\u003e\n\u003cli\u003eValmaseda‑Castell\u0026oacute;n E, Berini‑Ayt\u0026eacute;s L, Gay‑Escoda C. Inferior alveolar nerve damage after lower third molar extraction: prospective study of 1,117 extractions. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2001;92(4):377\u0026ndash;383. doi:10.1067/moe.2001.118367\u003c/li\u003e\n\u003cli\u003ede Melo Albert DG, Gomes AC, Hummig KL, et al. Accuracy of CBCT for predicting IAN exposure: systematic review. J Craniomaxillofac Surg. 2019;47(5):768\u0026ndash;775. doi:10.1016/j.jcms.2019.02.020\u003c/li\u003e\n\u003cli\u003eMatzen LH, Christensen J, Wenzel A. Patients\u0026rsquo; risk of nerve injury after MTM removal based on OPG vs CBCT. Oral Surg Oral Med Oral Pathol Oral Radiol. 2013;115(4):463\u0026ndash;470. Available from: https://www.sciencedirect.com/science/article/pii/S2212440313000332\u003c/li\u003e\n\u003cli\u003eGadiwalla Y, Shah N, Renton T, et al. Review of national and international third molar guidelines. Int J Oral Maxillofac Surg. 2021;50(5):691\u0026ndash;698. doi:10.1016/j.ijom.2020.05.013\u003c/li\u003e\n\u003cli\u003eKapila SD, Nervina JM. CBCT in orthodontics: indications and hazards. Semin Orthod. 2015;21(3):152\u0026ndash;160. Available from: https://www.sciencedirect.com/science/article/pii/S1073874615000474\u003c/li\u003e\n\u003cli\u003eLudlow JB, Timothy R, Walker C, Hunter R, Benavides E, Samuelson DB, et al. Effective dose of dental CBCT: meta‑analysis. Dentomaxillofac Radiol. 2015;44(1):20140197. Available from: https://academic.oup.com/dmfr/article/44/1/20140197/7263895\u003c/li\u003e\n\u003cli\u003eGuerrero ME, Noriega J, Castro C, et al. Relationship between mandibular third molars and mandibular canal using CBCT. Oral Surg Oral Med Oral Pathol Oral Radiol. 2012;114(5 Suppl):S34\u0026ndash;S41. Available from: https://www.sciencedirect.com/science/article/pii/S2212440312003239\u003c/li\u003e\n\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":"mandibular third molar, inferior alveolar nerve, mandibular canal, CBCT, cortical wall defect, coronectomy, panoramic radiography","lastPublishedDoi":"10.21203/rs.3.rs-8360194/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8360194/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eObjectives: \u003c/strong\u003eTo quantify the association between mandibular third molar (MTM) root position relative to the mandibular canal (MC) and MC cortical wall defects on cone‑beam CT (CBCT), and to explore impaction‑type and age correlates.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMaterials and methods:\u003c/strong\u003e Retrospective cross‑sectional analysis of impacted MTMs (n=344) from private radiology centers in Yemen. Variables: coronal‑plane root position (superior/buccal/lingual), Winter angulation and Pell \u0026amp; Gregory depth, MC wall integrity (intact vs defective), and orthopantomogram (OPG) warning signs (interrupted white line, diversion, narrowing). Associations were evaluated with chi‑square tests (α=0.05). (Figure 2).\u003c/p\u003e\n\u003cp\u003eMC integrity by position: superior intact 94/128 (73.4%); buccal intact 18/66 (27.3%), defects 48/66 (72.7%); lingual intact 95/150 (63.3%); χ² p\u0026lt;0.001 (Figure 1).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions: \u003c/strong\u003eBuccal root position was the dominant predictor of MC cortical wall defects, followed by lingual; superior roots were least risky. Findings support selective CBCT when OPG suggests close MTM–MC proximity to guide nerve‑sparing strategies (e.g., coronectomy) in high‑risk anatomy.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical relevance: \u003c/strong\u003eCBCT refines risk stratification beyond OPG when bucco‑lingual relationships are uncertain and may influence the choice of nerve‑sparing techniques.\u003c/p\u003e","manuscriptTitle":"Root position relative to the mandibular canal is the dominant predictor of cortical wall defects in impacted mandibular third molars: a CBCT-based retrospective study in a Middle-Eastern cohort","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-30 00:24:45","doi":"10.21203/rs.3.rs-8360194/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":"7dcea1dc-ce91-422f-beb1-15dac1fd91da","owner":[],"postedDate":"December 30th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":60027481,"name":"Health sciences/Anatomy"},{"id":60027482,"name":"Health sciences/Diseases"},{"id":60027483,"name":"Health sciences/Health care"},{"id":60027484,"name":"Health sciences/Medical research"}],"tags":[],"updatedAt":"2026-01-02T06:39:11+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-30 00:24:45","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8360194","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8360194","identity":"rs-8360194","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}